Nutrition Test 4
anencephaly
- type of neural tube defect in which much of the brain does not form properly or is missing - can result from genetic causes and from folate deficiency
spina bifida
- type of neural tube defect in which the spine does not form properly before birth and fails to enclose the spinal cord
fate of pyruvate: anaerobic conditions
- under anaerobic conditions, pyruvate is converted to lactic acid, another three-carbon molecule - lactic acid releases two H+, forming lactate - lactate is released into the bloodstream - liver removes lactate from bloodstream and recycles it into glucose, via a pathway called the Cori cycle - liver releases newly made glucose into circulation - six ATP are required to make glucose from lactate - too inefficient to continue indefinitely
alcohol as an energy source
- does not yield glucose - does not yield amino acids - yields fat
alcohol effects on the brain
- impairs brain functioning and damages brian - increases risk of stroke
dietary adequacy of riboflavin
- 1.1 mg/day for women - 1.3 mg/day for men - typical american: - 1.8 mg/day for women - 2.5 mg/day for men - no UL has been established - excess is rapidly eliminated in urine and so an excess does not appear to cause side effects
thiamin deficiency
- 1.2 mg/day for men - 1.1 mg/day for women - beriberi: characterized by weakness, poor muscular coordination, and abnormal functioning of the cardiovascular, digestive, and nervous systems
dietary adequacy of vitamin b-6
- 1.3 to 1.7 mg/day - average US adult consumes more - deficiency is rare but can result from alcoholism or genetic conditions that affect vitamin B-6 metabolism - dermatitis - anemia - convulsion - depression - confusion
dietary adequacy of niacin
- 14 to 16 mg/day - niacin recommendations are provided as niacin equivalents (NEs) - 1 NE = 1 mg niacin - takes into consideration the niacin content and the contribution of tryptophan to niacin
dietary adequacy of vitamin b-12
- 2.4 μg/day - vegans need to be concerned about their intake because plant foods are not sources - vitamin B-12 deficiency is characterized by nerve damage and megaloblastic anemia - muscle weakness - smooth and shiny tongue - confusion - difficulty walking and maintaining balance - numbness and tingling sensations
dietary adequacy of biotin
- 30 μg/day - typically met by american adults - severe deficiencies rarely occur because intestinal bacteria produce some biotin and it is found in a wide variety of foods - skin rash - hair loss - convulsions - neurological disorders - developmental delays in infants - no UL has been set as it appears to be nontoxic
dietary adequacy of folate
- 400 μg (DFE)/day for adults - 600 μg (DFE)/day during pregnancy - 500 μg (DFE)/day in breastfeeding women - risk of folate deficiency increases: - during periods of rapid growth, such as pregnancy, infancy, and childhood - with excess alcohol consumption
dietary adequacy of pantothenic acid
- 5 mg/day for adults - most Americans consume the AI amount or more - deficiency is rare - when experimentally induced, signs and symptoms include headache, fatigue, impaired muscle coordination, GI tract disturbances, and burning feet syndrome (severe aching in the feet) - alcoholics may develop deficiency of this and other B vitamins - no UL has been set, as there are no reports of toxicity
dietary adequacy of vitamin c
- 75 mg/day for women - 90 mg/day for men - occurs in the small intestine - as intake increases, the rate of absorption decreases - the kidneys increase excretion of the vitamin in response to high intake - taking megadoses may be wasteful
classifying vitamins: fat soluble
- A (retinol) - D (cholecalciferol, ergocalciferol) - E (alpha-tocopherol, other tocopherols) - K (phylloquinones, menaquinones)
phosphorylation and ATP cycling
- ATP can be reformed by phosphorylation, an anabolic reaction that attaches a phosphate (Pi) group to ADP - ATP formation requires energy input - ATP cycling is the primary way that cells "earn" and "spend" energy - energy from catabolism of food macromolecules is used to build ATP - ATP is broken down and the energy released is used to power cellular work
alcohol effects on the pancreas
- impairs pancreatic function - can cause inflammation of the pancreas and increases the risk of pancreatic cancer
vitamin A and vision
- The retina contains specialized nerve cells essential for vision (rods and cones) - both need retinol to function properly - rods covert retinol to retinal - night blindness can occur if retinol is unavailable - retinal binds to protein opsin to form rhodopsin - vitamin A-containing protein that is needed for vision in dim light
vitamin c toxicity
- UL for vitamin C is 2,000 mg/day - when people exceed this amount, gastrointestinal upset and kidney stones can occur
vitamin b-6 toxicity
- UL is 100 mg/day - nerve damage
alcohol use disorder
- a "problem drinker" experiences problems at home, work, and school that are associated with their drinking habits - according to the National Institutes of Health (NIH), a person with a severe drinking problem has an alcohol use disorder (AUD) - problem drinkers and people with an AUD engage in behaviors that place themselves and others in danger, such as drinking and driving - according to estimates, 5% of Americans who were 12 years of age and older had an AUD in 2018
vitamin E and the cell membrane
- a cell needs a healthy cell membrane to function properly - free radicals can damage polyunsaturated fatty acids in the cell membranes - such damage can weaken the membrane - vitamin E donates a stabilizing particle to the free radical, so it is no longer destructive
vitamins
- a complex organic compound that regulates certain metabolic processes, and meets certain criteria: - cannot be synthesized by the body or make enough to maintain good health - occurs naturally in foods - deficiency disorder occurs if substance is missing from the body or is not properly metabolized - health is restored by supplying missing substance
cytochrome c
- a component of the electron transport chain; facilitates the bonding of hydrogen ions with oxygen, forming "metabolic water" - some energy released during electron transfer is used to attach a Pi group to ADP, forming ATP - the complete catabolism of one glucose molecule yields approximately 30 to 32 molecules of ATP
tocopherols
- a group of four structurally similar forms of vitamin E
carnitine
- a molecule that helps fatty acids enter the mitochondria - fatty acids are catabolized in the mitochondria - they are "activated" in cytoplasm by binding to coenzyme A, using energy from 2 ATP - meat, fish, poultry, milk; human biosynthesis - deficiency: rarely occurs - no UL established Doses of 3 g/day: nausea, vomiting, diarrhea, abdominal cramps
choline
- a part of acetylcholine - neurotransmitter associated with attention, learning and memory, muscle control, and other nervous system function - neurotransmitter and phospholipid synthesis; methionine metabolism - adult AI: 425 to 550 mg - widely distributed in foods; human biosynthesis - deficiency: liver damage - adult UL = 3,500 mg/day - toxicity signs: fishy body odor and reduced blood pressure - production of phospholipids in cell membranes - used by the liver to synthesize part of a lipoprotein that transports lipids - participates in the metabolism of the amino acid methionine
dietary management of cystic fibrosis
- a patient taking pancreatic enzyme pills should take those pills with all meals and snacks - patients should eat several small, nutrient-dense meals during the day - people who have cystic fibrosis can add calories and protein to their diet by: - consuming a nutrient-fortified shake - topping meals with added cheese and drinking whole milk - dipping fruits and vegetables in dips or peanut butter - adding chicken, salmon, eggs, and/or nuts to a vegetable salad
ariboflavinosis
- a riboflavin deficiency disease characterized by fatigue, inflammation of the mucous membranes that line the mouth and throat, and glossitis
ethanol
- a simple, two-carbon molecule that is more commonly called "alcohol" - soluble in water - beer and wine contain simple carbohydrates and small amounts of certain minerals and B vitamins - hard liquors have essentially no nutritional value other than water
biological activity
- a vitamin's degree of potency or effects in the body - may differ between natural and synthetic vitamins
nonalcoholic fatty liver
- abnormal accumulation of fat in the liver that is not caused by alcohol consumption - excessive alcohol consumption can cause a buildup of fat in the liver - can also occur due to insulin resistance and high fructose consumption - insulin-resistant cells do not take up glucose and fatty acids from the bloodstream or store energy effectively - blood glucose levels stay high (hyperglycemia) long after a meal - lipolysis in adipocytes is not restricted - excess fatty acids released into bloodstream - influx of glucose and fatty acids stimulates triglyceride synthesis in the liver - high fructose intake may contribute to the increasing incidence of NAFLD - fructose can only be catabolized in the liver - excess consumption can rapidly promote lipogenesis and fat accumulation - fatty liver a sign of impending liver damage
kidney disease and vitamin D
- about 11% of Americans live with chronic kidney disease - as the disease progresses, the risk of bone loss and fracture, CVD, immune suppression, and death increases - the kidneys are not able to convert calcidiol into calcitriol - low vitamin D status is common in patients with chronic renal failure (CRF) - higher intake of vitamin D improves survival rates
digestion and absorption of vitamin b-12
- absorbing natural vitamin B-12 from food requires a complex series of steps -intrinsic factor (IF) is a substance produced in the stomach that facilitates intestinal absorption of vitamin B‒12
ketone bodies
- acetoacetate, beta-hydroxybutyrate, and acetone; produced in the liver from acetyl CoA - released into the bloodstream
cellular work
- activities in cells requiring energy, such as building and transporting molecules
fat
- adipose cell triglycerides: 80,000 to 100,000
folate deficiency
- affects cells that rapidly divide, such as red blood cells (RBCs) - the body constantly replaces old or worn-out RBCs - without folate, RBC precursor cells that reside in bone marrow enlarge, but cannot divide normally because they are unable to make new DNA
storing triglycerides
- after a fat-containing meal, most of the lipids are incorporated by the liver into very-low-density lipoproteins (VLDLs), and released into the blood - lipoprotein lipase is an enzyme that enables adipocytes and other cells to access lipoproteins' lipid contents - free fatty acids and glycerol enter the cells - after entering, triglyceride is re-created - requires very little energy input
fat burns in the absence of carbohydrate
- after a meal, cells use glucose first as an energy source in order to keep blood sugar levels within a normal range - once levels return to normal, cells switch to burn fat for energy - lipolysis and beta-oxidation are inhibited by the presence of insulin and ATP, and activated by glucagon - fatty acid synthesis is activated by insulin and citrate from carbohydrate metabolism, and inhibited by glucagon
what causes cells to become cancerous
- aging - family history - tobacco use - radiation exposure - exposure to certain environmental substances - certain viral and bacterial infections - elevated levels of certain hormones - consuming alcohol or certain foods in excess - physical inactivity and excess body fat
treatment of cystic fibrosis
- airway clearance, diet, medications and, in some cases, surgery - nutritional management of cystic fibrosis improves disease management and prevents serious complications of the disease, including: - destruction of pancreatic tissue - blockage of the ducts leading to and from the pancreas - reduced enzymatic activity that can cause nutrient malabsorption
ATP yields
- alanine: 14 ATP - palmitic acid: 106 ATP - glucose: 30-32 ATP
effects of alcohol on liver matabolism
- alcohol directly affects the liver by disrupting the normal metabolism of glucose, fatty acids, and amino acids - the two dehydrogenase reactions in alcohol metabolism result in the transfer of an electron to NAD+, producing NADH - NADH accumulates and NAD+ becomes depleted, changing the ratio of NADH to NAD+, which affects normal metabolic pathways in liver cells: - the rate of glycolysis slows - more pyruvate is converted to lactic acid - ATP production from glucose is impaired - can lead to hypoglycemia because not enough NAD+ is available to maintain normal gluconeogenesis rate - due to lack of NAD+, the activity of the citric acid cycle slows - some acetyl CoA molecules enter the citric acid cycle for energy - liver cells use most of the excess acetyl CoA to make fatty acids for triglyceride synthesis - accumulation of triglycerides in liver cells can cause "alcoholic fatty liver"
retinol
- alcohol form of vitamin A and the most active form of vitamin A in the body
factors that influence alcohol metabolism
- amount of alcohol - timing of consumption - sex - body size and composition - age - prior drinking history
retinol activity equivalents
- amounts of vitamin A in food are often reported as micrograms of retinol activity equivalents (RAE) - 1 REA is equal to: - 1 μg retinol - 12 μg beta-carotene - 24 μg alpha-carotene or beta-cryptoxanthin
neural tube
- an embryonic structure that eventually develops into the brain and spinal cord - pregnant women who are deficient in folate increase the risk of their infant being born with neural tube defects (NTDs)
inborn errors of metabolism
- an inherited metabolic defect - glycogen storage disease (GSD) - cannot make or degrade glycogen properly - abnormal glucose metabolism occurs - signs and symptoms include hypoglycemia, fatigue, irritability, and liver and kidney enlargement
coenzyme action
- are small molecules that interact with enzymes, enabling the enzymes to function
vitamin malabsorption (cystic fibrosis)
- as a result of pancreatic enzyme insufficiency and mucus blocking passageways, fat-soluble vitamin digestion and absorption are often impaired - aitamin A is involved in immunity, and poor immune response is a concern of people with cystic fibrosis because they are already prone to frequent respiratory infections - vitamin D deficiency is almost universal in cystic fibrosis patients - vitamin E deficiency was once common, but is now rare; those with a deficiency may experience poor resistance to disease and heart abnormalities - vitamin K deficiency is common in cystic fibrosis patients
waste excess energy
- as an alternative to energy storage, the body can "waste" some food energy consumed in excess
metabolic responses to an overnight fast
- as blood glucose levels fall during early part of an overnight fast, the pancreas secretes glucagon - liver increases glycogenolysis - blood glucose levels are maintained - when liver glycogen stores are depleted, glucagon stimulates gluconeogenesis in liver - liver and muscle tissue mainly use fatty acids for fuel - upon "breaking the fast" with a carbohydrate-rich meal, the insulin response promotes a shift from a catabolic to an anabolic state
folate and disease
- associated with elevated blood levels of homocysteine, a recognized risk factor for CVD - elevated homocysteine levels may also be a marker or risk factor for Alzheimer's disease (AD)
seasonal variation in sunlight intensity
- because Earth is tilted on its axis relative to its plane of orbit around the sun, the intensity of solar radiation varies seasonally - this variation is smallest in the tropics and increases toward the poles
carotenoids with vitamin A
- besides beta-carotene, common carotenoids include lutein, zeaxanthin and lycopene - the body cannot convert them to vitamin A - may function as beneficial antioxidants in the human body - green, leafy vegetables are high in lutein and zeaxanthin - tomato products are high in lycopene
diet pills
- between 1933 and 1938, a drug call 2,4-DNP, marketed as Dinitriso and Nitromet, was used as a diet pill for the treatment of obesity - previously used to produce explosives - found to have side effect of increasing metabolism when factory workers lost weight upon exposure - works similar to uncoupling proteins - quickly banned by the Federal Food, Drug and Cosmetic Act due to extreme adverse side effects, including death
wernicke-korsakoff syndrome
- degenerative brain disorder associated with a deficiency of thiamin - most commonly caused by excessive alcohol consumption - symptoms include abnormal eye movements, staggering gait, and distorted thought processes
caffeinated alcoholic beverages
- caffeinated alcoholic beverages (CABs) are commercially available drinks that are popular among younger drinkers - mixing caffeine and alcohol can be dangerous - caffeine can mask some of the effects of alcohol by increasing feelings of alertness - those consuming CABs may not realize their level of impairment, which can increase the risk of overconsumption - the caffeine in the beverages does not affect the body's ability to metabolize alcohol - the person's BAC will not be reduced as a result of drinking CABs
carbohydrate and fat: energy stores in the body
- carbohydrate - fat - when more fuel is available than necessary to meet immediate needs, excess sources of energy are stored - used when not consuming foods - the body prefers to use stored fat and glucose - only uses body proteins as a last resort
classifying vitamins: vitamin-like substances
- carnitine - choline - inositol - lipoic acid - taurine
beta-carotene
- carotenoid that the body can convert to vitamins A - alpha-carotene and beta-cryptoxanthin can also be converted into a biologically active retinoid
cortisol
- catabolic hormone made in the adrenal glands - promotes protein catabolism - stimulates the liver to increase use of amino acids for gluconeogenesis - also known as a "stress hormone" because it is released in stressful situations - low blood glucose levels - severe injuries - physiological states that evoke anxiety or fear
alcohol dehydrogenase pathway
- catabolic pathway that metabolizes alcohol in the liver
catabolism of fructose
- catabolized via the fructolysis pathway - occurs only in liver cells - fructose is broken down into two products that feed into the glycolytic pathway, then follow same route as glucose catabolism - one of them, glyceraldehyde, can be converted to glycerol - glycerol is the backbone of triglyceride molecules - fructose is thought to be uniquely fat-promoting compared to other sugars
alcohol effects on the skin
- causes flushing of the skin and heat loss
alcohol effects on the liver
- causes liver cells to fill with fat, eventually resulting in hepatitis, cirrhosis, and liver failure - increases risk of liver cancer
epithelial cells
- cells that form protective tissues that line the body
obtaining energy from protein
- cells use amino acids to synthesize essential proteins - after these needs are met, cells may catabolize amino acids for ATP or convert them into glucose or fatty acids - glucose and fatty acids are primary energy sources
beta-oxidation
- chemical pathway involved in the catabolism of a fatty acid - occurs in mitochondria - fatty acid molecules are cleaved into two-carbon segments that are converted into acetyl CoA that enters the citric acid cycle - one NADH and one FADH2 are produced each time a two-carbon segment is removed from the fatty acid - these yield about four ATP when they shuttle electrons into the ETC - NADH and FADH2 formed from metabolizing the resulting acetyl CoA in the citric acid cycle also shuttle electrons to the ETC, generating even more ATP - thus the amount of energy derived from a fatty acid depends on the length of its carbon chain - fatty acids with longer chains contain more chemical energy than those with shorter chains
vitamin-like compounds
- choline - carnitine - inositol - taurine - lipoic acid
biotin
- coenzyme needed for synthesizing glucose and fatty acids - essential for regenerating oxaloacetate in the TCA cycle - RDA: 30 μg - eggs, peanuts, salmon, pork, liver, mushrooms, sunflower seeds - deficiency: rarely occurs: skin rash, hair loss, convulsions, and other neurological disorders; developmental delays in infants - UL not determined
functions of vitamin c
- collagen synthesis - antioxidant activity - immune function - necessary for synthesis of bile and certain neurotransmitters and hormones like cortisol, aldosterone, and thyroxin - enhances iron (Fe) absorption - plants are major sources of nonheme iron (Fe3+) - the small intestine absorbs Fe2+ more readily than Fe3+ - vitamin c promotes iron absorption by donating an electron to Fe3+ forming Fe2+ - adding vitamin C-rich foods to meals can increase absorption of nonheme iron
forms of vitamin D (calciferol)
- comes from both plant and animal sources - ergocalciferol (D2) - cholecalciferol (D3)
lipoic acid
- component of metabolic reactions that remove CO2 from compounds, antioxidant - meats, liver, yeast; human biosynthesis - it is unnecessary to obtain it from dietary sources because the body synthesizes it
peripheral neuropathy
- condition characterized by severe sensory nerve damage - can be caused by megadoses of vitamin B‒6 - toxicity signs and symptoms include walking difficulties and numbness of the hands and feet - large doses of vitamin B‒6 are often recommended to treat premenstrual syndrome (PMS), morning sickness, and carpal tunnel syndrome - there is not enough evidence to support these uses
ketoacidosis
- condition that occurs in the absence of insulin when excess acetoacetate and beta-hydroxybutyrate in the bloodstream lower the blood's pH - potentially life-threatening - excessive thirst - frequent urination - blood glucose greater than 250 mg/dL - "fruity" odor to breath - if untreated can lead to coma and death
standard drink
- contains 13 to 14 g of alcohol; it is approximately: - 12 ounces of beet - 5 ounces of win - 1 1/2 ounces of liquor
catabolism of galactose
- converted in a two-step process into glucose, which is then catabolized via the glycolytic pathway - conversion of galactose to glucose occurs mainly in liver - the pathway is also present is some other tissues
food sources of riboflavin
- cow's milk, yogurt, and other dairy products - enriched cereal - almonds - liver - mushrooms - broccoli and asparagus - spinach and other green leafy vegetables - exposure to light causes rapid breakdown - this is why milk products are packaged in opaque containers
alcohol effects on the heart
- damages heart muscles, resulting in enlargement of the heart and heart failure - causes hypertension
triglycerides as an energy source
- does no yield glucose - does not yield amino acids - yields fat
signs of problem drinking
- drink to relax, forget your worries, or improve your mood - lose interest in food as a result of your drinking habits - binge drink - Lie about your drinking habits or try to hide them - drink alone - hurt yourself or someone else while drinking - were drunk more than three or four times last year - need to drink more alcohol than you used to drink to get "high" - feel irritable when you are not drinking - have medical, social, or financial problems caused by drinking habits - have been cited for driving while intoxicated (DWI) or driving under the influence of alcohol (DUI)
hangovers
- drinking alcohol at a rate that exceeds the body's ability to metabolize it may experience a hangover the next day - the headache and nausea, sensitivity to light and noise, fatigue, and thirst are in part explained by the accumulation of acetaldehyde in various tissues - if a person were to consume just 1 teaspoon of pure acetaldehyde through the mouth, they would experience an instant hangover - the toxic effects of alcohol on the brain, and alcohol's dehydrating and hypoglycemic effects, are also thought to contribute to the discomfort
metabolic responses to starvation
- during starvation, where no food or energy is consumed for an extended period of time, additional changes are made - muscle cells rely more heavily on fatty acids for energy - adipose tissue increases lipolysis - fatty acid levels in blood increase - alternative sources of glucose are needed to fuel red blood cells and nervous tissue - liver produces new glucose by gluconeogenesis - liver cells rely more on ketogenesis - converts acetyl CoA to ketone bodies - brain starts using ketone bodies for fuel - muscle cells begin proteolysis, the breakdown of amino acids - the liver can use some of the amino acids for gluconeogenesis - the breakdown of adipose and muscle tissue causes extreme weight loss, muscle wasting, and weakness
COVID-19 and vitamin D
- early evidence suggests a link between vitamin D deficiency and COVID-19 severity - countries with higher rates of this deficiency have seen more cases of COVID-19 and more serious health consequences, including death - to optimize blood levels of vitamin D: - consume recommended amounts in the diet - consult with healthcare provider about taking a vitamin D supplement (vitamin D may interact with other supplements and medications)
vitamin E and chronic disease
- early studies indicated that populations who ate vitamin E-rich diets had lower risk of heart disease, and that vitamin E might reduce the risk of cancer - some researchers promoted use of vitamin E megadoses to slow the decline in mental functioning associated with Alzheimer's disease - studies evaluating vitamin E's benefits in people with signs of mild cognitive impairment (which can progress to Alzheimer's disease) have found conflicting results - recently, major long-term trials have failed to show that high intakes of vitamin E consistently reduce the risk of these chronic diseases
biotin and raw eggs
- eating raw eggs frequently or in excess can cause a biotin deficiency - the protein avidin inhibits biotin absorption - it often takes the consumption of 24 or more raw egg whites in a day before biotin absorption is impaired - consuming cooked eggs is not a cause for concern because heating denatures avidin, and kills any potentially dangerous bacteria
energy shuttles: NAD+ and FAD
- energy in the body is transferred between molecules in the form of electrons (e-) - because electrons are negatively charged, they are usually accompanied by positive hydrogen ions (H+) - two different coenzymes accept and transport these ions: - nicotinamide adenine dinucleotide (NAD+) - niacin-containing coenzyme - Flavin adenine dinucleotide (FAD) - riboflavin-containing coenzyme
food sources of niacin
- enriched cereals - beef liver - tuna - salmon - pultry - pork - mushrooms - with adequate dietary protein, the human body can synthesize niacin from tryptophan
vitamin enrichment and fortification
- enrichment of grains helps prevent deficiency diseases from lack of thiamin, riboflavin, niacin, folate, and iron - does not replace vitamin E, vitamin B-6, magnesium, several other micronutrients, and fiber naturally present in unrefined grains - experts thus promote consumption of whole-grain products - some manufacturers fortify foods and beverages with vitamins - may cause excessive consumption of a few vitamins while reducing the intake of others
hormone sensitive lipase (HSL)
- enzyme in fat cells (adipocytes) that removes the three fatty acids from a triglyceride - facilitates lipolysis - activated when blood sugar and insulin levels are low - glycerol and fatty acids enter bloodstream - fatty acids are carried to tissues by albumin, a water-soluble protein - liver can convert glycerol to pyruvate or glucose
gastric alcohol dehydrogenase
- enzyme that detoxifies some alcohol while it is in the stomach - liver is primary site for metabolism of absorbed alcohol - a moderate drinker can metabolize 12 to 15 g of alcohol (approximately 1 standard drink) per hour - excess circulates in bloodstream until liver can metabolize it
aldehyde dehydrogenase
- enzyme that helps convert acetaldehyde to acetate, a less toxic substance - acetate can be converted to acetyl CoA, which can enter citric acid cycle or be used in fatty acid or ketone body synthesis
alcohol and gout
- excess alcohol intake can interfere with the kidneys' ability to excrete uric acid, a by-product of nucleic acid (DNA and RNA) metabolism - uric acid accumulates in bloodstream and can form tiny, needlelike crystals in body fluids - the crystals contribute to the signs and symptoms of gout - extremely painful form of arthritis that often causes inflammation in the joints of the toes - people with gout should avoid drinking excess alcohol because it aggravates their condition
bioavailability
- extent to which the digestive tract absorbs a nutrient and how well the body uses it - factors that affect bioavailability include: - life-stage and nutrient status of individual - changes to GI transit time - health conditions affecting absorption of fats - food processing and preparation techniques - source of vitamin
age-related macular degeneration (AMD)
- eye disease resulting in changes in the macula of the eye, causing distorted vision
retinoids (performed vitamin A)
- family of compounds commonly called vitamin A (retinol, retinal, retinoic acid)
latitude and vitamin D status
- if you live in North America south of the 33rd parallel and are outdoors when sunlight is most intense during the day, you are likely to obtain enough sun exposure to synthesize vitamin D most of the year
food sources of vitamin D
- fish liver oils and fatty fish, especially salmon, herring, and catfish, are among the few foods that naturally contain vitamin D - vitamin D-fortified milk, cereal, orange juice, and margarine - vitamin D content of foods is often in International Units: 1 μg of vitamin D equals 40 IU
food digestion and absorption
- folate naturally occurs in foods as folate polyglutamate - not as biologically available as synthetic form, folic acid (folate monoglutamate) - no enzyme activity is required to digest folic acid - to digest natural folate, specific intestinal enzymes remove all except one of the glutamates, resulting in the folic acid form, which is methylated and absorbed in the small intestine - within body cells, folate is activated by removal of the methyl group, which requires vitamin B-12
folate toxicity
- folate that occurs naturally in foods does not appear to be toxic - UL for synthetic form is 1,000 μg/day - excess can "mask" a vitamin B‒12 deficiency
measuring carotenoid levels in the body
- for many years, blood levels of carotenoids have been measured in research studies evaluating their effects on health - more recently, instruments have been developed to measure a person's dermal, or skin, carotenoid levels - they appear to accurately measure carotenoids in the body - quicker and less invasive than taking a blood sample
cholecalciferol (Vitamin D3)
- form of vitamin D found in animal food sources
ergocalciferol (Vitamin D2)
- form of vitamin D found in plant food sources
gamma-tocopherol
- form of vitamin E that has significantly lower biological activity than alpha-tocopherol - also found in foods
alpha-tocopherol
- form of vitamin E used by the body; found in most foods and vitamin E supplements
glucagon, cortisol, and epinephrine: catabolic metabolism
- glucagon, cortisol, and epinephrine are hormones that instruct cells to use catabolic rather than anabolic pathways - glucagon is secreted from the alpha cells of pancreas in response to low blood sugar levels - signals liver to increase glycogenolysis and gluconeogenesis from glucogenic amino acids - raises blood glucose levels
amino acids and energy metabolism
- glucogenic amino acids can be broken down into either pyruvate or intermediates of the citric acid cycle - ketogenic amino acids enter the catabolic energy pathways as acetyl CoA - some amino acids are both glucogenic and ketogenic
food sources of vitamin K
- green leafy vegetables such as kale, turnip greens, salad greens, cabbage, and spinach - broccoli and green beans - major food sources of vitamin K2 are: - egg yolks - butter and certain cheeses - liver and beef - some fermented foods
coenzymes
- group of organic compounds that assist enzymes with chemical reactions - many b vitamins serve as coenzymes or are components of coenzymes
loss of vitamin E
- harvesting, processing, storage, and cooking methods influence the amount of vitamin E retained in food - most of the vitamin E is lost during milling of whole grains, and it is not restored by enrichment - vitamin E is highly susceptible to destruction by exposure to oxygen, metals, light, and high temperatures
PLP in homocysteine metabolism
- helps convert homocysteine to cysteine - folate and vitamin B-12 are also needed - lack of vitamin B-6 can cause homocysteine accumulation, which may contribute to cardiovascular disease (CVD)
vitamin K deficiency
- hemmorage - the body stores very little vitamin K, but deficiencies among adults are rare - may occur after long courses of antibiotics, with very-low-fat diets, or with liver diseases/conditions that impair fat absorption - most reliable sign of vitamin K1 deficiency is an increase in the time it takes for blood to clot - babies are generally born with low vitamin K stores and their immature GI tracts do not yet produce vitamin K - newborns generally receive an injection of vitamin K at birth - vitamin K2 deficiency can cause increased blood vessel calcification and increased risk of bone fracture
diet and cancer prevention
- high intakes of fruits and vegetables reduce cancer risk - rich sources of vitamin c, carotenoids and other phytochemicals that may have antioxidant activity - antioxidants protect DNA from free radical damage, preventing potentially cancer-causing mutations - antioxidant supplements may increase the risk of lung and prostate cancers
ketogenic diet
- high-fat, moderate- to low-protein, and very-low-carbohydrate diet - ketosis is the formation of excess ketone bodies - result of ketogenic diet - causes hunger reduction - reduces insulin levels, allowing for increased lipolysis and loss of fat mass - may be used to treat obesity, metabolic syndrome, type 2 diabetes, epilepsy, Alzheimer's disease, and cancer
acetaldehyde
- highly toxic substance formed during the first step of the alcohol dehydrogenase pathway
parathyroid hormone (PTH)
- hormone secreted in response to low blood calcium levels - signals bones to release calcium, and stimulates kidneys to increase vitamin D production and decrease calcium elimination in urine
use of fats for energy
- human cells cannot use fatty acids to make new glucose - the glycerol backbone of triglycerides can be converted to glucose in the liver - an adequate supply of glucose for energy is important - red blood cells, the brain, and the nervous system are more dependent on glucose as a fuel source compared to other tissues that can use fat as fuel
when amino acids are in excess
- if diet provides an excess of amino acids and cells do not need energy: - the liver and kidneys can use glucogenic amino acids to make glucose (gluconeogenesis) - ketogenic amino acids can be converted into acetyl CoA - can be used to produce ketone bodies when carbohydrate intake is limited - can feed into lipogenic pathways
regulation of metabolism
- if surplus of food energy is consumed, hormones determine in part whether it is stored or burned - hormones are "chemical messengers" secreted by specific organs - circulate through blood to stimulate and regulate cellular activities of target tissues - the specific actions of each metabolic hormone depend on the body's metabolic state: - fed, after a meal has been consumed - fasted, when a meal has not recently been consumed
riboflavin (vitamin B-2)
- important for energy metabolism as part of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) - the two coenzymes play key roles in enzymatic reactions, including those that are critical to fatty acid and folate metabolism - the liver, kidneys, and heart store small amounts of riboflavin - any excess intake is rapidly excreted in the urine
folic acid - fortified corn mesa
- in 2016, the FDA approved the fortification of corn masa flour with folic acid, also called masa - often used to make foods such as corn chips, tortillas, tortilla chips, tamales, and taco shells - frequently consumed by many individuals of Mexican and Central American descent - the fortification with folic acid may reduce the risk of delivering a baby with a NTD - hispanic women in the U.S. are 20% more likely to deliver a baby with a NTD than non-Hispanic white women
vitamin A and the visual cycle
- in dark conditions, retinal is attached inside opsin to make rhodopsin - light activates rhodopsin by causing retinal to change chape, which causes opsin to change shape - activated rhodopsin stimulates rod cell changes that result in vision - following rhodopsin activation, retinal detaches from opsin - energy is required to bring retinal back to its original form - retinal attaches to opsin to form rhodopsin - return to step 1
energy
- in living organisms, power derived from sunlight or food to perform cellular work - can neither be created not destroyed - can undergo transformations - for ex: body cells take energy sotred in food and convert it into a usuable form of energy - human cells obtain energy by releasing chemical energy stored in macronutrients (carbohydrates, lipids, proteins) and alcohol - energy in food is measured in kilocalories (Calories) - calls cannot release energy from vitamins, minerals, or water
vitamin b-6 in baby formula
- in the early 1950s, some infants became unusually irritable and developed convulsions after being fed a commercial formula - the vitamin B-6 in the formula had been destroyed by excessive heating during manufacturing - the convulsions may have resulted from a lack of neurotransmitters in the infants' brains - the babies were effectively treated with vitamin B-6
25-hydroxyvitamin D (calcidol)
- inactive form of vitamin D, made in the liver from cholecalciferol
alcohol effects on the abdomen
- increases fat deposits in abdominal
alcohol effects on the mouth, throat, voice box
- increases risk of cancer
alcohol effects on the esophagus
- increases risk of cancer of the esophagus
alcohol effects on the colon and rectum
- increases risk of colon and rectal cancer
alcohol effects on the breast
- increases the risk of breast cancer
obesity and insulin resistance
- insulin binds to the insulin receptor on muscle, fat, and liver cells -allows glucose and fatty acids to be taken up from the blood and stored - in obesity, the increase in adipose tissue results in abnormal metabolic changes - cells become unresponsive to insulin - insulin resistance - associated with type 2 diabetes
insulin promotes energy storage
- insulin directs liver and muscle cells to: - slow down their glycogenolysis rates - increase their rate of glycogenesis - insulin promotes energy storage: - shifts glucose molecules into storage as glycogen in liver and muscle - increases fatty acid uptake and triglyceride synthesis by adipocytes - stimulates protein synthesis in cells
actions of insulin
- insulin promotes anabolism, such as glycogenesis, triglyceride synthesis, and protein synthesis
alcohol effects on the small intestine
- interferes with nutrient absorption
metabolism
- involves a continuous transfer of energy in the body - energy released from catabolic reactions is used to fuel anabolic reactions in cells
alcohol effects on the stomach
- irritates stomach lining and increases risk of stomach cancer
osteomalacia
- is a condition characterized by softening of the bones as a result of inadequate vitamin D status in adults - adults who are confined indoors or almost fully covered when outside are at risk
collagen
- is a fibrous protein that gives strength to connective tissue such as bone, cartilage, and tendons - vitamin c can act as an antioxidant by donating electrons to radicals - may limit self-destruction of white blood cells (WBCs) due to free radical generation during immune response - in excessive amounts, vitamin C can act as a prooxidant, a substance that promotes production of free radicals
myelin sheath
- is a structure that wraps around and insulates a part of a certain nerve cell cells - vitamin B‒12 is needed for maintenance of this structure, which is needed for nerve communication
megaloblastic anemia
- is a type of anemia characterized by large, immature RBCs - a deficiency of folate and/or vitamin B‒12 can lead to this form of anemia
cystic fibrosis
- is an inherited respiratory disease caused by a defective gene that leads to the overproduction of thick and sticky mucus - it negatively affects the lungs, pancreas, liver, intestines, sinuses, and sex organs - left untreated, children with cystic fibrosis usually experience delayed growth and malnutrition - most states conduct newborn screening for cystic fibrosis - blood test sent to lab to detect for genetic abnormalities - If positive, sweat test follows: - a high level of salt in sweat is a positive sign for cystic fibrosis
functions of vitmain D
- is necessary for regulation of calcium and maintenance of phosphorus levels in the blood, and the production and maintenance of healthy bones - stimulates small-intestine to absorb calcium and phosphorus - stimulates bone cells to form calcium phosphate, the major mineral compound in bone - works with parathyroid hormone (PTH) - regulation of neuromuscular and immune function - Reducing inflammation - may also reduce a person's risk of heart disease, cancer, diabetes mellitus, multiple sclerosis, asthma, and depression
vitamin c
- or ascorbic acid, is a cofactor that performs a variety of important cellular functions, primarily by donating electrons to other compounds
ketogenesis
- ketone body formation - acetone is eliminated through the breath and has a distinctive, "fruity" odor - levels in breath can be measured to determine if a person is in early stages of ketosis - cells, excluding liver cells, can use acetoacetate and beta-hydroxybutyrate as sources of acetyl CoA
food sources of folate
- leafy vegetables - liver - legumes - asparagus and broccoli - orange juice - enriched grain products and fortified cereals - may be measured in micrograms of dietary folate equivalents (DFEs) to account for the difference in absorption of folic acid and of natural forms of folate - it is destroyed by heat, oxidation, and ultraviolet light
electron transport chain
- linked series of enzymes that synthesize water and ATP during aerobic energy metabolism - coenzymes NADH and FADH2 carry hydrogen ions and high-energy electrons here
food soruces of vitamin A
- liver - butter - fish liver oils - eggs - aitamin A-fortified milk, yogurt, margarine, and cereals are important sources in the U.S. - carrots, spinach and other leafy greens, pumpkin, sweet potatoes, broccoli, mangoes, and cantaloupe are rich sources of beta-carotene
food sources of biotin
- liver - eggs - peanuts - salmon - pork
carbohydrate
- liver glycogen: 300 to 400 - muscle glycogen: 1,200 to 1,600
vitamin K and blood clotting
- liver needs vitamin K1 to make certain clotting factors - inactive clotting factors and inactive platelets are normal conditions - injury to blood vessels; tissues exposed - inactive platelets and inactive clotting factors in blood activated - prothrombin --> thrombin - fibrinogen --> fibrin (clot)
food-cobalamin malabsorption
- malabsorption of vitamin B‒12 due to the inability to release the vitamin from animal protein during the digestive process - as people age, HCl production in the stomach declines - also due to: - chronic alcoholism - gastric bypass surgeries for weight reduction - gastritis (inflammation of the stomach lining) - certain medications
vitamin K in newborns
- many organizations recommend intramuscular (IM) delivery of vitamin K for newborns to prevent potential bleeding associated with a vitamin K deficiency - not all parents follow this guideline - a recent study found that the parents most likely to refuse IM vitamin K for their newborn were white, over the age of 30, and college graduates, and intended to exclusively breastfeed their infants - experts recommend that healthcare providers share more information about the importance of vitamin K for newborns during the prenatal period
anaerobic metabolism
- metabolic pathways for ATP production that do not require oxygen - much less energy ismade under low-oxygen conditions
aerobic metabolism
- metabolic pathways for ATP production that require oxygen - occurs in mitrochondria if the cell's oxygen supply is adequate
catabolism
- metabolic pathways that break down larger molecules into smallers ones - cells transform some of the energy in macronutrients into usable chemical energy to power chemical reactions - the rest is transformed into heat energy - cannot be used to perform cellular work, but helps maintain normal body temperature
anabolism
- metabolic pathways that build larger molecules from smaller ones - requires energy, supplied by catabolic reactions
classifying drinkers
- moderate: up to 2 drinks/day for males and up to 1 drink/day for females - heavy: 15 or more drinks/week for males and 8 or more drinks/week for females - binge: 5 or more drinks/occasion (about 2 hours) for males and 4 or more drinks/occasion (about 2 hours) for females - the 2020-2025 Dietary Guidelines for Americans emphasize the importance of limiting alcohol consumption to moderate intakes - regular consumption of alcoholic beverages can make it difficult to stay within recommended calorie intake and may increase consumption of added sugars
1.25-dihydroxyvitamin D (calcitriol)
- most biologically active form of vitamin D - made in the kidneys from calcidiol
roles of enzymes
- most chemical reactions that occur in living cells require specific enzymes that facilitate (catalyze) reactions - enzymes remain unchanged - usually require use of coenzyme
water-soluble vitamins as coenzymes
- most water-soluble vitamins function as components of specific coenzymes - the coenzyme forms of B vitamins are often found in foods - digestion releases the free form of the vitamin - after absorption, cells combine the B vitamin with a nitrogen-containing, nonprotein compound, to synthesize the corresponding coenzyme
dietary adequacy of vitamin K
- no RDAs for vitamin K have been established - the AI for vitamin K is: - 120 μg/day for men - 90 μg/day for women - the intake of vitamin K tends to increase with age
signs and symptoms of cystic fibrosis
- no bowel movements in the first 24 to 48 hours of life - failure to gain weight normally during infancy and childhood - salty-tasting skin - abdominal pain, bloating, gassiness, and severe constipation - nausea and loss of appetite - foul-smelling feces that contain mucus or float - chronic cough with significant mucus accumulation in the sinuses or lungs
carbohydrate metabolism
- normally, human cells rely on glucose, fat, and protein metabolism to function properly - central nervous system (CNS) cells are more dependent on glucose than fatty acids or amino acids to meet energy needs - most body cells are adaptable and can use multiple sources of energy - carbohydrate metabolism will focus on glucose - cells can also use fructose and galactose to synthesize ATP, particularly in the liver
liver versus muscle glycogenolysis
- occurs in liver when blood sugar levels begin to fall, such as during an overnight fast - liver releases glucose from glycogen degradation into the bloodstream for uptake by cells - muscle tissue breaks down glycogen for glucose catabolism to occur in muscle cells
food sources of vitamin b-12
- only bacteria, fungi (mushrooms and molds), and algae can synthesize vitamin B‒12 - meat - milk and milk products - poultry - fish - shellfish - eggs - liver is one of the riches sources, because the vitamin is stored in this organ
free radical activity
- oxidation is thought to promote chemical changes in cells that lead to heart attack, stroke, cancer, Alzheimer's disease, aging process - some free radical formation in the body is necessary and provides benefits
riboflavin
- part of FMN and FAD, coenzymes needed for carbohydrate, amino acid, and lipid metabolism - RDA: 1.1 to 1.3 mg - cow's milk, yogurt, and other dairy products; enriched breads and cereals - deficiency: inflammation of the mouth and tongue, eye disorders - UL not determined
niacin (vitamin B3)
- part of NAD and NADP, coenzymes needed for energy metabolism - RDA: 14 to 16 mg - enriched breads and cereals, beef, liver, tuna, salmon, poultry, pork, mushrooms - deficiency: pellagra - diarrhea -dermatitis - dementia - death - UL = 35 mg/day - flushing of facial skin, itchy skin, nausea and vomiting, liver damage - coenzymes participate in at least 200 reactions, including pathways involved in the release of energy from macronutrients
vitamin B-6
- part of PLP, coenzyme needed for amino acid metabolism, involved in neurotransmitter synthesis and hemoglobin synthesis - conversion of tryptophan to niacin - transamination reactions that form nonessential amino acids - PLP helps produce heme, a component of hemoglobin - the iron-containing protein in red blood cells (RBCs) that transports oxygen - if vitamin B‒6 is unavailable, anemia can develop - PLP is involved in homocysteine metabolism - RDA: 1.3 to 1.7 mg - meat, fish, poultry, potatoes, bananas, spinach, sweet red peppers, broccoli - deficiency: dermatitis, anemia, depression, confusion, and neurological disorders such as convulsions - adult UL = 100 mg/day nerve destruction
folate
- part of THFA, coenzyme needed for DNA synthesis and conversion of cysteine to methionine, preventing homocysteine accumulation - RDA: 400 μg - dark green, leafy vegetables, papayas; asparagus; broccoli; orange juice; enriched breads and cereals (folic acid) - deficiency: megaloblastic anemia, diarrhea, neural tube defects in embryos - adult UL = 1000 μg/day may stimulate cancer cell growth
thiamin
- part of TPP, coenzyme needed for carbohydrate metabolism and the metabolism of certain amino acids; may help produce neurotransmitters - RDA: 1.1 to 1.2 mg - pork, wheat germ, enriched breads and cereals, legumes, nuts - deficiency: Beriberi and Wernicke-Korsakoff syndrome: weakness, abnormal nervous system functioning - upper limit [UL] not determined
pantothenic acid
- part of coenzyme A that is needed for synthesizing fat and that helps release energy from carbohydrate, fat, and protein - RDA: 5 mg - beef and chicken liver, sunflower seeds, mushrooms, yogurt, fortified cereals - deficiency: rarely occurs - UL not determined
vitamin B-12
- part of coenzymes needed for various cellular processes, including folate metabolism; maintenance of myelin sheaths - RDA: 2.4 μg - animal foods; fortified cereals; fortified almond, soy, or rice milks - deficiency: pernicious anemia: megaloblastic anemia and nerve damage resulting in paralysis and death - UL not determined
glycogenesis
- pathway that links glucose units together for storage as glycogen - cccurs in liver and muscle cells - specific enzymes bind single glucose molecules together into long, branched chains of glycogen - the body stores limited amounts of glycogen
vitamin E deficiency
- people who have diseases that interfere with fat absorption may become deficient - long-term deficiency damages the nervous system - nerve damage - loss of neuromuscular control - blindness - reduced function of immune system - may cause a form of anemia in preterm infants
niacin deficiency
- people with alcoholism - people with anorexia nervosa - people with rare disorders that disrupt tryptophan metabolism - early signs and symptoms of mild niacin deficiency include poor appetite, weight loss, and weakness - if affected person continues to consume a niacin-deficient diet, pellagra develops
food sources of vitamin c
- peppers - citrus - papaya - broccoli - cabbage - berries - potatoes - vitamin c-fortified fruit drinks and ready-to-eat cereals also supply vitamin c - vitamin c is very unstable in the presence of heat, oxygen, light, alkaline conditions, and the minerals iron and copper
blood alcohol concentration (BAC)
- percentage that reflects the concentration of alcohol in the bloodstream - in the USA, a BAC of 0.08% is the legal limit for intoxication for automobile operators who are 21 years of age or older
forms of vitamin K
- phylloquinone - menaquinone - menadione
food sources of vitamin b-6
- pistachio nuts and walnuts - salmon - beef - potatoes - bananas - spinach - sweet red pepper - broccoli - is lost during the refining process of grains, and is not added back to grain products during enrichment - many cereals are fortified with vitamin B-6 - excessive heat results in loss of the vitamin
vitamin K and osteoporosis
- pivotal for bone strength - some clinical studies evaluating the effects of vitamin K intake (from either dietary or supplemental sources) on bone health and fracture risk have found beneficial results - but there are conflicting findings - healthcare practitioners caution that more research is needed on dosing effects and the safety of vitamin K for bone health
sources of vitamins
- plants - animals - fungi - bacteria - algae
7-dehydrocholesterol
- precursor for vitamin D found in skin - UV light converts it to cholecalciferol, which circulates to the liver - vitamin D is thus not considered an essential nutrient
food sources of pantothenic acid
- present in a wide variety of foods (in Greek, pantothen means "everywhere") - fortified cereals -liver - sunflower seeds - mushrooms - peas - walnuts and berries - meat - cows milk - many kinds of vegetables
nonexercise activity thermogenesis (NEAT)
- process by which energy is expended during spontaneous physical activity, such as fidgeting
adaptive theromgenesis
- process of energy dissipation as heat that occurs in mitochondria - rates change in response to environmental temperature, diet, and hormones - involves activation of uncoupling proteins in mitochondria that increase heat production at the expense of ATP production
epinephrine
- produced by the adrenal glands - stimulates catabolism by: - increasing glycogenolysis and lipolysis in liver and muscle - increasing lipolysis in adipose tissue - secreted in large amounts in response to stressful conditions that increase need for quick energy - physical activity - "fight-or-flight" situations
functions of vitamin A
- production - growth and development - function - maintenance - epithelial cells
avidin
- protein found in raw egg whites that binds biotin, thus preventing absorption of the vitamin
folate and vitamin b-12 work together
- recycle methionine: - THF transfers CH3 to vitamin B‒12, which then transfers the CH3 to homocysteine, forming methionine - when vitamin B‒12 is unavailable, folate cannot be used, and a deficiency of folate occurs, even if dietary intakes are adequate
glossitis
- refers to a swollen and dor tongue - riboflavin deficiency
inositol
- regulatory role in cells - fruits, beans, grains, nuts; human biosynthesis - inositol-containing phospholipids are precursors of eicosanoids, a family of compounds that have numerous hormone-like actions - may be an essential nutrient only under certain conditions
vitamins A and chronic disease
- research suggests an association between diets rich in fruits and vegetables and a lower risk of certain cancers, heart disease, and age-related macular degeneration, a leading cause of blindness in the U.S. - age-related macular degeneration (AMD)
vitmain b-12 deficiency
- result from problems that interfere with its intestinal absorption - risk for neural tube defects is greater in cases of low maternal vitamin B-12 status - consumption of foods fortified with vitamin B-12 is often recommended for pregnant women - been associated with abnormal neurological function and psychological health - including depression and dementia
forms of vitamin A
- retinoids - retinol - retinyl esters - carotenoids - beta-carotene
converting dietary sources into active forms of vitamin A
- retinyl esters, from animal foods, and beta-carotene, from plant food sources, are converted into active retinoids
cheilosis
- scaling and cracking of the skin around the corners of the mouth - riboflavin deficiency
vitamin c deficiency
- scurvy - an early sign is pinpoint bleeding under the skin (petechiae) - as the disease progresses, the affected person's skin bruises easily and the gums become spongy and bleed at the slightest touch - joints swell and ache - teeth fall out - without treatment, victims eventually die, most likely from infection
microsomal ethanol oxidizing system (MEOS)
- secondary pathway for processing alcohol in the liver - used when excessive amounts of alcohol are consumed - also produces acetaldehyde that is processed to yield acetyl CoA - wastes energy in the form of heat - causes vasodilation in alcoholics, who thus are at risk of hypothermia
elite athletes and vitamin D deficiency
- similar to other healthy adults, elite athletes are at risk for vitamin D deficiency - research suggests that over half of all athletes have suboptimal blood levels of vitamin D - deficiency is greatest in athletes training at higher latitudes, during the winter and early spring seasons, and in sports that are primarily indoors - experts believe there may be a positive relationship between vitamin D deficiency and injury risk in athletes
skeletal muscle and liver glycogen stores (healthy average adult)
- skeletal muscles: 325g - liver: 90 to 100g - total: 415 to 425g
roles of vitamins
- some act as hormones - some participate in chemical reactions by accepting or donating electrons - vitamins regulate various body processes, including cell division, development, and growth - most have more than one chemical form that functions in the body - some have precursors (provitamins or previtamins) that do not function as vitamins until the body converts them into active forms
pernicious anemia
- some people can experience a vitamin B-12 deficiency due to autoimmune disorder that causes the stomach to stop making intrinsic factor - development of pernicious ("deadly") anemia, a condition caused by a lack of intrinsic factor and characterized by vitamin B-12 deficiency, nerve damage, and megaloblastic red blood cells - treatment involves: - monthly vitamin B-12 injections or a nasal gel that contains the vitamin - taking large doses of vitamin b-12
folate, vitamin c, and vitamin e
- some studies have found an inverse association between cancer risk and folate status - others indicate folate supplementation has no effect or even increases the risk of cancer - there is some encouraging scientific evidence that vitamin c may be useful in treating cancer - it may lower the effectiveness of certain cancer-fighting medications - the relationship between vitamin E and cancer is unclear - one large study found that supplementation with alpha-tocopherol increased prostate cancer risk
chemical pathways
- specific chemical reactions that occur in sequences - used to access and use energy storied in "biological fuels"
retinyl esters
- storage form of vitamin A
ascorbic acid (vitamin C)
- substance needed for connective tissue synthesis and maintenance, antioxidant, synthesis of neurotransmitters and certain hormones, immune system functioning - RDA: 75 to 90 mg (nonsmokers) - peppers, citrus fruits, cherries, broccoli, cabbage, berries - deficency: scurvy: poor wound healing, pinpoint hemorrhages, bleeding gums, bruises, depression - UL = 2,000 mg/day diarrhea and GI tract discomfort
antioxidants
- substance that gives up electrons to free radicals to protect cells - protects molecules in cells, such as polyunsaturated fatty acids and DNA, from being oxidized - cells regulate oxidation reactions by using antioxidants, such as vitamin E
oxidizing agent (oxidant)
- substance that removes electrons from atoms or molecules - an atom or a molecule that loses one or more electrons has been oxidized
adenosine diphosphate (ADP)
- the molecule that forms when ATP loses its last phosphate group during ATP catabolsim - comprised of adenosine bound to two (di-) inorganix phosphate groups
free radical
- substance with an unpaired electron - generated from oxidation reaction - highly reactive and unstable - can remove electrons from stable molecules such as proteins, fatty acids and DNA, damaging them - if uncontrolled, a chain reaction can occur in which excessive oxidation takes place and affects many cells
vitamin-like compounds requirements
- substances that maintain normal metabolism but are not essential since the body can synthesize them - the need generally increases during rapid growth periods - for example in preterm infants - average healthy adult is not at risk of deficiencies - more research needed to determine whether to include them in total parenteral solutions - liquid mixtures that provide nourishment to those who are unable to eat normally; administered intravenously
energy metabolism
- sum of all the chemical pathways in the body that break down molecules to release energy and use energy to build new molecules - these chemical pathways enable the human body to obtain and use energy from macronutrients and alcohol - metabolic reactions may be catabolic or anabolic
food sources of vitamin E
- sunflower seeds - almonds - plant oils (sunflower, safflower, canola, and olive oils) and products made from them (margarine and salad dressing) - fish - whole grains - nuts and seeds - certain vegetables
multivitamin-multimineral supplement
- supplement that contains two or more vitamins and minerals - over one-third of Americans report use of supplements - if healthy and on an adequate diet, it is not necessary to consume 100% of every vitamin each day - bacteria in lower intestinal tract produce certain vitamins, particularly biotin and vitamin K, which can be absorbed to some extent - under certain conditions, the body can synthesize vitamin D, niacin, and choline
lipogenesis
- synthesis of fatty acids - two-carbon acetyl CoA units are bound together to form the hydrocarbon chain of the fatty acid - the fatty acid elongates and stores energy - when carbohydrates are consumed, glucose is catabolized to make ATP, inhibiting the breakdown of fatty acids - as a result, synthesis and storage of triglycerides occurs in adipocytes - high carbohydrate consumption can thus result in accumulation of body fat
menadione
- synthetic form of vitamin K - can be converted into menaquinone in the body
dietary adequacy of vitamin D
- the RDA for adults under age 70 is 15 μg/day (600 IU/day) - nearly half of American adults have low blood levels of vitamin D - according to the 2020 to 2025 Dietary Guidelines for Americans, vitamin D is a nutrient of public health concern - factors that are associated with low blood levels include: - darker skin tones - overweight - using electronic media or games > 4 hours/day - drinking milk < 1 x/week
diet adequacy of vitamin A
- the RDA for vitamin A is 700 to 900 μg RAE - the average American diet provides enough vitamin A and its precursors to meet the RDA - groups at risk for vitamin A deficiency in the U.S.: - preschool children who do not eat enough vegetables - people on very-low-fat diets - low-income urban residents - older adults, and people with severe alcoholism, fat malabsorption, or liver diseases
dietary adequacy of vitamin E
- the RDA for vitamin E is 15 mg/day of alpha-tocopherol - many Americans do not meet this recommendation - deficiency is rare - healthy body stores vitamin E in body fat, skeletal muscle, and liver - amounts may be reported as number of IUs (1 mg alpha-tocopherol is about 1.5 IU of the natural form)
vitamin E toxicity
- the UL for vitamin E is set at 1,000 mg/day of alpha-tocopherol for healthy adults - consuming high amounts of vitamin E in foods does not have a negative effect on health - excessive amounts taken as supplements may interfere with vitamin K's role in blood clotting
niacin toxicity
- the adult UL for niacin is 35 mg/day - no reports have indicated toxicity from niacin obtained naturally in foods - megadoses can be prescribed to reduce elevated LDL cholesterol levels and increase HDL cholesterol levels - side effects of this therapy can include: - flushing of skin, usually on face and chest - GI tract upset, such as nausea and vomiting - liver damage
summary of using amino acids for energy
- the amount of ATP formed by the catabolism of an amino acid carbon skeleton depends on where it entered the catabolism pathways
summary of energy metabolism
- the amount of energy from stored ATP and phosphocreatine (the first system) is small - the amount of energy from stored carbohydrates (the second system) is greater, but still limited - the amount of available fuel for exercise from fats (the third system) is essentially limitless
coenzymes: health and nutritional significance
- the b vitamins thiamin, pantothenic acid, niacin, and riboflavin are components of coenzymes used in energy metabolism - if diet does not supply them in adequate amounts, cells cannot synthesize coenzymes for catabolism - cannot convert enough pyruvate into acetyl CoA to meet energy needs - common symptoms of these deficiencies include fatigue and weakness
mitochondria
- the chemical pathway that initiates the breakdown of glucose and produces some ATP occurs in the cytoplasm - organelles that synthesize most of the ATP that cells need to function - have an outer membrane and an inner membrane
folate during pregnancy
- the damage to an embryo due to lack of folic acid occurs early, often before a woman knows she is pregnant - to help guard against neural tube defects, a woman of childbearing potential should track her DFE level to make sure it is above 400 μg - the easiest way to be certain is to take a daily supplement - during pregnancy, a woman's folic acid intake should be increased to 600 μg/day - for women with a previous neural tube defect-affected pregnancy, even higher doses of folic acid may be beneficial
glycolysis
- the first phase of glucose catabolism - leads to ATP production from glucose oxidation - oxidation involves loss of electrons so that energy is transferred to another molecule - possible electrons acceptors in orxidation reactions include: the electron shuttles NAD+ and FAD and oxygen - anaerobic pathway - occurs in cytoplasm - glucose is broken down to two molecules of pyruvate, a 3 carbon molecule - two NADH and four ATP molecules are formed - two ATP molecules are used, so there is a net gain of two
niacin in corn
- the niacin content of corn is considerably higher than that of most other vegetables and grains - but is tightly bound to a protein that resists digestion - people who eat corn as their staple food are prone to develop pellagra, the niacin deficiency disease - the traditional Mexican diet is corn-based, but pellagra was not a widespread disease in Mexico - the practice of soaking corn kernels in lime water to prepare tortillas helps free the niacin, enhancing its absorption - also done for corn products such as hominy and grits, which are thus sources of niacin
pellagra
- the niacin deficiency disease characterized by dermatitis, diarrhea, dementia, and death - 4 Ds of pellagra
preparing amino acids for catabolism: removing nitrogen
- the nitrogen group must be removed before an amino acid can be used for ATP production - removed by deamination or transamination - deamination results in production of ammonia, potentially toxic at high levels - deamination and transamination require the coenzyme pyridoxal phosphate (PLP) - vitamin B-6 is a component of PLP - a deficiency negatively affects protein metabolism
citric acid cycle
- the oxidation of acetyl CoA is the second phase of glucose catabolsim - a complex series of chemical reactions that are involved in energy metabolism - acetyl CoA is converted to CO2 and H2O - occurs twice for each glucose molecule that enters catabolism (once for each acetyl CoA) - oxaloacetate: four-carbon molecule that is an important intermediate of the citric acid cycle - coenzymes NAD+ and FAD that pick up hydrogen ions and high-energy electrons are important products
digestion and absorption of vitamin K
- the presence of dietary fat, bile, and pancreatic juice enhances vitamin K absorption in the small intestine - following absorption: - some is stored in the liver - some is incorporated into lipoproteins for transport in the bloodstream - the liver also breaks down vitamin K and eliminates the vitamin's by-products by adding them to bile
vitamin absorption
- the small intestine is the primary site of vitamin absorption - does not absorb 100% of the vitamins in food - absorption tends to increase when body needs more of a particular micronutrient - the body's requirements for vitamins increase during periods of growth, such as infancy and adolescence, and during pregnancy and breastfeeding - fat-soluble vitamins are chemically similar to lipids and are in fatty portions of food - fat digestion processes facilitate absorption of fat-soluble vitamins - adding a small amount of fat to low-fat foods can enhance absorption of fat-soluble vitamins - GI tract conditions and diseases can reduce vitamin absorption and result in deficiencies - may require large oral doses of vitamin supplements or injections of vitamins
alcohol absorption and metabolism
- the stomach and small intestine rapidly absorb alcohol - absorption slowed if alcohol is consumed with meals - absorption is faster if alcohol is in carbonated beverages or mixed with soft drinks - provides 7 kcal/g, but is not a nutrient - when consumed in excess, can damage every organ and cause death - to reduce the harmful effects of alcohol, the body detoxifies the simple molecule by converting it into less damaging compounds - gastric alcohol dehydrogenase - blood alcohol concentration (BAC)
alternate sources of glucose: glyconeigenesis
- the synthesis of glucose from noncarbohydrate precursors: - glycerol - lactate - pyruvate - many amino acids
thyroid hormone
- the thyroid gland at the base of the throat secretes two hormones collectively called thyroid hormone - helps body adapt by increasing or decreasing the rate of metabolism: can have catabolic or anabolic actions - increases rate of glucose catabolism, lipolysis, and protein synthesis - cells can develop and grow normally - levels increase during growth and development - levels decrease during long periods of starvation or fasting
thiamin (B-1)
- the vitamin component of a coenzyme that is important for energy metabolism as part of thiamin pyrophosphate (TPP) - necessary for the breakdown of carbohydrates to release energy and for the metabolism of branched-chain amino acids - necessary for the synthesis of neurotransmitters, chemicals produced by nerve cells that enable the cells to communicate with other nerve cells
vitamin b-12 (cobalamin)
- the vitamin that is a component of coenzymes that participate in a variety of cellular processes, including transfer of CH3 groups in the metabolism of folate - also needed for homocysteine metabolism and folate conversion to coenzymes involved in metabolic reactions, such as DNA synthesis
preserving the vitamin content of foods
- there are several ways to preserve the vitamin content of food - consume highly perishable produce like berries and leafy vegetables soon after harvest or purchase - store fresh produce at temperatures near freezing, in high humidity, away from air - avoid exposure to excessive heat, alkaline substances, light, and air - cook vegetables in small amounts of water, using quick cook methods - steaming - stir frying
vitamin K toxicity
- there is no UL set for vitamin K - nevertheless, people should avoid consuming more than the recommended amounts of vitamin K
energy metabolism vitamins
- thiamin - riboflavin - niacin - pantothenic acid - biotin - vitamin B-12 - vitamin B-6
classifying vitamins: water-soluble
- thiamin (thiamine, B-1) - riboflavin (B-2) - niacin (B-3, nicotinamide, nicotinic acid) - B-6 (pyridoxine) - B-12 (cobalamin, cobalamine) - biotin (H) - pantothenic acid (B-5) - folate (folic acid) - C (ascorbic acid)
b vitamins and thier coenzymes
- thiamin: thiamin pyrophosphate (TPP) - roboflavin: flavin adenine dinucleotide (FAD, FADH2)/flavin monoculeotide (FMN) - niacin: nicotinamide adenine dinucleotide (NAD+, NADH, NADP+)/nicotinamide adenine dinucleotide phosphate (NADP+, NADPH) - patothenic acid: coenzyme A (CoA) - vitamin b-6: pyridoxal phosphate (PLP)
forms of vitamin E
- tocopherols - alpha-tocopherol - gamma-tocopherol
thiamin toxicity
- toxicity from consuming high amounts of thiamin from food or supplements is rare - probably because the excess is readily excreted in urine - no UL has been established
energy storage
- triglycerides are the most energy-dense macronutrient group - the body can extract energy from dietary fat or fat stored in fat tissue - the body stores more energy in the form of triglycerides than glycogen - the body breaks down stored fat for energy when glucose levels are low
taurine
- vision, antioxidant in white blood cells, insulin action, cell growth and development - animal foods; human biosynthesis - the body synthesizes the amino acid taurine from the sulfur-containing amino acids methionine and cysteine - a component of bile - supplements are unnecessary - the body of a healthy person can make adequate amounts
vitamin A absorption and transport in the body
- vitamin A precursors in plant foods are not as well absorbed as retinol in animal foods - once absorbed, vitamin A is transported with lipids in chylomicrons to tissues for use or storage - over 90% stored in liver - retinol-binding protein (RBP): transports vitamin A in the blood
vitamin A toxcitiy
- vitamin A should not be taken in excess during pregnancy, as it is a teratogen, an agent that causes birth defects - the UL for vitamin A is 3,000 μg/day - can cause liver damage in excess - toxicity signs and symptoms include headache, nausea, vomiting, visual disturbances, hair loss, bone pain, and bone fractures
immune function vitamins
- vitamin A, C, D, E
growth and development vitamins
- vitamin A, D - choline
bone health vitamins
- vitamin A, D, K, C
vitamin A deficiency
- vitamin A-deficient epithelial cells produce too much keratin, a tough protein found in hair, nails, and the outmost layer of skin - xerophthalmia is a condition affecting the eyes that results from a vitamin A deficiency - eventually leads to blindness - vitamin A deficiency during pregnancy can lead to several adverse health outcomes for both mother and baby - important for fetal eye health - essential for fetal organ and skeletal development - pregnant women should not take a vitamin A supplement without consulting their healthcare provider due to birth defect risk
animo acid metabolism vitamins
- vitamin B-6 - folate - vitamin B-12 - vitamin C - choline
red blood cell formation vitamins
- vitamin B-6 - vitamin B-12 - folate - riboflavin (indirect)
vitamin D and sunlight
- vitamin D is not widespread in food - the body needs sunlight (UV light) exposure to synthesize it - required sun exposure time depends on location, time of day and year, and the person's age and skin color - earth's atmosphere blocks UV light - for people living north of the 33rd parallel, the angle of the winter sun is such that the sun's rays must pass through more of the atmosphere than at other times of the year - the skin cannot make sufficient amounts of previtamin D during winter - skin contains melanin, a brown pigment - can prevent skin from absorbing too much solar radiation and forming toxic amounts of vitamin D - darker skin contains more melanin than lighter skin - people with darker skin or a medium degree of pigmentation should expose their skin to the sun for at least 15 minutes a day during the summer for adequate vitamin D synthesis - wearing sunscreen is important in the prevention of skin cancer and premature aging - but it may limit the skin's ability to make vitamin D
rickets
- vitamin D-deficiency disorder in children resulting in improper bone growth - bones are soft and can become malformed - can be prevented and treated by sunlight exposure, vitamin D supplements, and vitamin D-rich foods - severe rickets is uncommon in the United States - but there has been a recent increase in the number of cases among infants and toddlers - human breast milk contains insufficient amounts of vitamin D to prevent rickets - breastfed infants should consume a supplement containing 400 IU/day to reduce risk - formula-fed infants should consume formula that is enriched with vitamin D - healthy children should continue to consume at least 400 IU/day through adolescence
functions of vitamin E
- vitamin E protects polyunsaturated fatty acids in cell membranes from being damaged by free radicals - such oxidative damage may be associated with the development of atherosclerosis (which contributes to heart attacks and stroke), cancer, and premature cellular aging and death - other roles include maintaining nervous tissue and immune system function
blood clotting vitamins
- vitamin K
phylloquinone
- vitamin K1 - found in plants
menquinone
- vitamin K2 - found in animals and fermented foods - also synthesized by bacteria that normally live in the intestinal tract, which can be absorbed by the bod - bacterial menaquinone contributes about 10% to the body's vitamin K supply - the biological activity of phylloquinone is different from that of menaquinone
scurvy
- vitamin c deficiency - deathly disease first associated with lengthy ocean voyages
vitamin c supplementation: heart disease & alzheimer's disease
- vitamin c may reduce the oxidation of LDL cholesterol, lowering the risk of CVD - studies have not provided consistent evidence that it reduces the risk of CVD or of dying from CVD - some studies suggest that high intake of vitamin C-rich foods may reduce the risk of Alzheimer's disease
antioxidant defense vitamins
- vitamin e - vitamin c (likely) - certain caroteniods
deficiency of vitamins
- vitamin needs can generally be met through a diet with adequate amounts of a wide variety of foods, including: - minimally processed fruits, vegetables, whole-grain breads and cereals, and quality protein foods - many Americans consume less than recommended amounts of vitamins A, D, E, and K - deficiency disorders result from inadequate diets or conditions that increase requirements, such as: - reduced intestinal absorption - higher-than-normal excretion of micronutrient - segments of the population at risk for vitamin deficiencies: - those with alcoholism - older adults - patients hospitalized for lengthy periods - people consuming very-low-fat and poorly planned vegan diets - people who suffer from anorexia nervosa, have intestinal conditions that interfere with absorption, or have metabolic defects that increase vitamin requirements
water-soluble vitamins
- vitamins that are hydrophilic and found in the watery portion of food; thiamin, riboflavin, niacin, vitamin B-6, pantothenic acid, folate, biotin, vitamin B-12, and vitamin C - dissolve in watery components of body - limited amounts are stored (exception is vitamin B‒12) - kidneys filter excess and eliminate them in urine - less likely to be toxic - the vitamin-like compounds choline, carnitine, and lipoic acid are also water soluble - not stored i large amounts - consume on a regular basis to prevent deficiency
fat-soluble vitamins
- vitamins that are hydrophobic and found in the lipid portions of food; vitamins A, D, E, and K - associate with lipids in the body - digested and absorbed with fats - stored in the body, primarily in liver and adipose tissue - can accumulate and cause toxicity
introducing vitamins
- vitamins were first defined in 1912 - Casimir Funk coined the term vitamine - vita: necessary for life - amine: a type of nitrogen-containing substance - the term was later changed to vitamin after it was determined that there were several kinds of these substances and not all were amines - it is unlikely that any vitamins still need to be discovered - babies thrive and grow on infant formula - people who cannot eat solid foods can live for years on synthetic liquid diets that contain all known nutritents
storing glucose
- when a person consumes a surplus of glucose, the body stores excess glucose as either glycogen or triglycerides
insulin: anabolic metabolism
- when blood glucose levels rise, beta cells in the pancreas secrete insulin - insulin attaches to receptors on cell membranes of insulin-responsive cells - results in signal to open glucose transport proteins in membrane - glucose enters the cytoplasm
vitamin D toxicity
- when excess vitamin D is consumed, the small intestine absorbs too much calcium from foods - in the absence of vitamin K2, it can be deposited in soft tissues, including kidneys, heart, blood vessels - can interfere with cells' ability to function, leading to cellular death - toxicity signs and symptoms include muscular weakness, loss of appetite, diarrhea, vomiting, and mental confusion - the body does not make toxic levels of vitamin D when exposed to sunlight - the UL for vitamin D is 100 μg/day (4,000 IU/day)
glycogenolysis
- when glucose is not available in blood, certain cells can obtain it by: - pathway that breaks down glycogen into glucose molecules - requires coenzyme pyridoxal phosphate (PLP) - primary sites for glycogen storage and degradation are liver and muscle tissue
ketone body formation
- when glucose is unavailable (during starvation or periods of low carbohydrate consumption), most cells can adapt to catabolize acetoacetate and beta-hydroxybutyrate for energy
metabolic syndrome
- when liver cells become insulin resistant, their ability to regulate glycogen synthesis and gluconeogenesis becomes altered - glucose still produced in liver and released into bloodstream - blood glucose levels rise - pancreas secretes more insulin - excess body fat is a major risk factor for metabolic syndrome and type 2 diabetes
fate of pyruvate: aerobic conditions
- when plenty of oxygen is available, pyruvate enters mitochondria - converted to acetyl coenzyme A (acetyl CoA) 2--carbon molecule - two moleciles of acetyl CoA formed from one molecule of glucose
functions of vitamin K
- when vitamin K1 is unavailable, the blood-clotting factors are inactive, and blood does not clot effectively - the liver synthesizes several blood-clotting factors, and needs vitamin K1 to produce four of them - vitamin K2 plays a role in bone health through the stimulation of bone formation and inhibition of bone breakdown - vitamin K2 regulates calcium in the body and prevents the deposition of calcium in soft tissues, such as blood vessels
food sources of thiamin
- whole grain and enriched breads and cereals - pork - legumes - orange juice - brewer's yeast - overheating food can destroy thiamin
toxicity of vitamins
- with vitamins, more is not necessarily better - when cells are saturated with a vitamin, they cannot accept additional amounts of it - continuing to take the vitamin can produce a toxicity disorder and may cause liver damage - vitamin toxicity is a concern when: - taking excessive amounts (megadoses) of supplements - consuming large amounts of vitamin-fortified foods regularly - in their natural states, most commonly eaten foods do not contain toxic levels of vitamins
vegan diets and breast feeding
- women who follow a vegan diet and breastfeed their babies may produce breast milk with inadequate amounts of vitamin B-12 - babies who are exclusively breastfed milk that is deficient in vitamin B-12 are likely to develop megaloblastic anemia and serious nervous system problems - mothers on an exclusively plant-based diet should not only take a vitamin B-12 supplement during pregnancy but also continue vitamin B-12 supplementation during lactation
riboflavin and migraines
- worldwide, 6% of men and 18% of women experience regular migraine headaches - high doses of riboflavin (200 to 400 mg) may be a low-cost, effective treatment in children and adults - some studies have found that supplemental riboflavin may reduce the incidence of migraines - other studies have shown a significant placebo effect and no benefit with riboflavin supplementation - more research is needed
carotenoids
- yellow-orange pigments in fruits and vegetables
carotenemia
- yellowing of the skin that results from excess beta-carotene in the body - harmless
amino acids as an energy source
- yield glucose except for ketogenic amino acids - yield amino acids - yield fat
glucose as an energy source
- yields glucose - yields amino acids only nonessential amino acids if N is available - yields fat
cirrhosis of the liver
-if a person with a fatty liver continues to consume alcohol, they are likely to develop eventually - condition characterized by the accumulation of scar tissue in the liver, which permanently damages the organ
adenosine triphosphate (ATP)
a high-energy phosphate compound that serves as energy "currency" of cells - energy released by the break down of macronutrients is captured in this chemical form - comprised of adenosin bound to three (tr-) inorganic phosphate groups (Pi) - when an enzyme cleaves the bond between the last two phosphate groups of ATP energy is released and cells can use energy for anabolic activities
