Nutrition Chapter 7

Recommended intake for vitamin C

90 and 75 mg/day for adult men and women. Smokers are advised to increase vitamin C intake by an additional 35 mg/day. UL of 2,000 mg/day has been set for supplemental vitamin C.

Dietary sources of vitamin D

Egg yolks, butter, whole milk, fatty fish, and mushrooms. Many dairy products and breakfast cereals are also synthesized with vitamin D. Vitamin D is quite stable and not destroyed by food preparation, processing, or storage. Can be synthesized through exposure to sunlight.

Dietary sources of riboflavin (B2)

Has yellow color. Is found in a variety of foods, such as liver, meat, dairy products, enriched cereals, and other fortified foods.

Recommended intake of pantothenic acid

AI level of 5mg/day has been established for adults. UL has not been set, but high intakes have been associated with nausea and diarrhea.

Recommended Intake for biotin

AI of 30 ug/day has been set for adults. No UL set.

Recommended intakes for vitamin K

AIs of 120 and 90 mg/day for men and women. No UL established

Dietary sources of biotin

Peanuts, tree nuts (such as almonds and cashews), mushrooms, eggs, and tomatoes

Recommended intakes for vitamin E

15 mg/day. High dose supplements can cause dangerous bleeding or hemorrhaging so a UL of 1,000 mg per day has been established.

Protecting water-soluble vitamins from destruction

Can be lost through exposure to air, water, heat, and/or light and others are often affected by acidity. Can prevent excessive loss by properly preparing and storing foods.

Vitamin D toxicity

Can cause calcium levels to rise in the blood and urine which causes calcium to be deposited in soft tissues, such as heart and lungs. Can lead to hypercalciuria which is high levels of calcium in the urine and associated with kidney stone formation and failure. UL is set at 4,000 IU per day for calcium in supplemental form.

Toxicity due to preformed vitamin A

Can cause hypervitaminosis A a condition characterized by blurred vision, liver abnormalities, and reduced bone strength. Very high doses of this can lead to birth defects such as neurological damage and physical deformities.

Recommended Vitamin B6 intake

1.3 to 1.7 mg/day for adults. UL has been set at 100mg/day

Dietary sources of vitamin A

Animal-based foods such as liver and other organ meats, and fatty fish. Whole-fat dairy products such as whole milk, cheese, and butter are also good sources of vitamin A. Plant-based foods contain provitamin A carotenoids. Plants that are brightly colored in red and yellow hues contain this such as cantaloupe, carrots, and peppers. Brightly colored animal based foods such as egg yolks, lobsters, crabs, and shrimp also contain provitamin A

Bio availability of riboflavin

Bioavailability increases when body needs more of it. Riboflavin found in animal-based foods is somewhat more bio available than that found in plant-based foods. Alcohol can also inhibit absorption.

Bio availability of folate

Body absorbs folate found in supplements and fortified foods (folic acid) better than it absorbs naturally occuring folate. Amount of folate present in a food is expressed in terms of dietary folate equivalent (DFE).

Vitamin D

Both nutrient and prohormone as it is a compound converted to an active hormone in the body. Exists in two forms ergocalciferol (vitamin D2) which is found in plant based foods and cholecalciferol (vitamin D3) which is found in animal based foods. Cholecalciferol can also be synthesized in the body.

Sources of B12

Can only be synthesized by microorganisms such as bacteria and fungi. Good dietary sources are shellfish, meat, fish, dairy products, along with many ready to eat breakfast cereals.

Recommended vitamin D intake

RDA of 600 IU/day for daults, increases to 800 IU for adults at age 71.

Recommended intake of riboflavin

RDAs are 1.2 and 1.1 mg/day for adult men and women respectively. No ULs are established.

Recommended intake for Niacin

RDAs are 16 and 14 mg/day NE for adult men and women respectively. Large doses of supplementary niacin can have ill effects, such as increased plasma glucose and liver damage, a UL of 35 mg/day NE has been set for niacin obtained from supplements and fortified foods. This value does not apply to niacin which occurs naturally in foods.

Recommended intake of thiamin (B1)

RDAs for thiamin are 1.2 and 1.1 mg/day for adult men and women respectively. Toxicity is rare so there is no UL set.

Vitamin K deficiency

Rare in healthy adults but can occur in some infants. Severe vitamin K deficiency in infants can lead to vitamin K deficiency bleeding which is characterized by uncontrollable bleeding, this is why it is recommended all newborns be given vitamin K injections. Vitamin K deficiency can also occur in children and adults with deficiencies that impair lipid function. Prolonged use of antibiotics can also kill bacteria which produce vitamin K.

Heat and light effect on riboflavin

Relatively stable during cooking but is quickly destroyed when exposed to excessive light

Vitamin names

Vitamins have letter designations, and many vitamins also have chemical names (ex. vitamin C is referred to as ascorbic acid). They can also have common names such as thiamin (B1) and riboflavin (B2).

Vision and vitamin A

When light enters eye it passes to inner back lining called retina. Retina consists of a layer of nerve tissue and millions of cells called cones and rods. Cones enable you to see color, whereas rods distinguish black from white. Rods contain thousands of rodopsin molecules, each of which is composed of cis-retinal (a form of vitamin A) and opsin (a protein). When light trike the rodopsin, the cis-retinal is converted to trans-retinal and separates from the opsin, this causes a neural signal to be sent to the brain which produces an image

Commonalities among water-soluble vitamins

1) All water-soluble vitamins dissolve in water 2) Body generally absorbs and transports water-soluble vitamins in a similar way 3) Body retains only small amounts of water-soluble vitamins so their overconsumption generally does not lead to toxic effects

Basics about vitamins

1) Complex organic compounds 2) Were first classified based on solubility in water. Fat-soluble vitamins were called vitamin A, while water soluble were called vitamin B. 3) Presently, there are at least 13 essential fat and water soluble vitamins

Tips for supplements

1) Consider safety: some supplements have ingredients that can be toxic (especially in high doses) 2) Be wary of results claiming a quick fix 3) Some products are harmful overtime and in large amounts 4) Term natural does not mean safe

Roles of vitamin D

1) Regulation of blood calcium levels. Low blood calcium stimulates the release of parathyroid hormone (PTH) from the thyroid gland. PTH stimulates the conversation of 25-(OH) D3 to calcitriol in the kidneys. Together calcitrol and PTH increase calcium absorption in the small intestine, decrease calcium excretion in the urine, and facilitate the release of calcium from the bones. 2) Role in blood pressure regulation 3) Muscle contraction 4) Nerve function 5) Cell differentiation and maturation

Recommended intake of folate

400 ug DRE everyday, RDA increases to 600 ug/day for pregnant women. UL of 1,000 ug a day has been set for folate derived form fortified foods and supplements

Antioxidant

A compound that donates electrons or hydrogen ions to other substances, inhibiting oxidation. Protects cells from free radicals, molecules that have one more unpaired electrons and are highly reactive and unstable. Free radicals can cause oxidation damage to cell membranes, DNA, and proteins which can lead to a variety of diseases.

Folate (vitamin B9) roles in body

A group of related water-soluble vitamins. Once absorbed by enterocytes, it combines with four hydrogen atoms, converting to its active form, tetrahydrofolate (THF). This active form facilitates single carbon transfers, which are needed to synthesize many important organic substances such as amino acids. It is also critical to the formation of DNA and RNA, which are essential for the growth, maintenance, and repair of every tissue in the body.

Fat-soluble vitamins

Absorbed mostly in the small intestine through the presence of dietary lipids and bile. After absorbed, fat-solbule vitamins are circulated away by chylomicra in the lymph. Fat=soluble vitamins eventually circulate to the blood as components of either lipoproteins (such as VLDLs) or transport proteins. The body is better able to store fat-soluble vitamins and therefore this can result more in toxicities.

Factors which influence bio availability of thiamin (B1)

Absorption increases when the body needs more of it, and decreaes when thiamin status is adequate. Compounds found in raw fish, coffee, tea, berries, Brussels sprouts, cabbage, and alcohol can interfere with thiamin's absorption, and sulfites, often added to processed foods as preservatives, can destroy thiamin. Vitamin Ca can increase thiamin bioavailability.

Nonprovitamin A carotenoid as antioxidant

Associated with reduced risks of heart disease, age-related eye disease, and certain types of cancer. Can also decrease risk of macular degeneration which is a chronic and age-related disease that causes deterioration of the retina.

Vitamin B 12 deficiency

Caused by either inadequate dietary intake or poor absorption. Occurs most often in vegans and infants breastfed by vitamin B12 deficient mothers. Also can occur when stomach cells fail to produce sufficient amounts of hydrochloric acid or intrinsic factor which is needed for vitamin B 12 absorption. Can also be caused by pernicious anemia, an autoimmune disease in which the immune system produces antibodies that destroy the intrinsic factor-producing cells of the stomach lining. Can cause secondary THF.

Riboflaviin deficiency

Causes a condition called arboflavinosis, generally does not occur on its own but is associated with general malnutrition. Signs and symptoms are cheilosis, sores on the outside and corners of the lips, stomatitis, inflammation of the mouth, and glossitis, inflammation of the tongue, as well as muscle weakness and confusion. Rare in the US but can occur in some alcoholics and in people with diseases that interfere with riboflavin utilization, such as thyroid disease.

Thiamin (B1) defciency

Causes beriberi, a life-threatening condition. Uncommon in the US, but prevalent in regions of the world that rely heavily on unfortified, refined rice as a major source of energy. Four forms.

Niacin deficiency

Causes pellagra a condition that results in dermatitis, dementia, diarrhea, and death (refereed to as the four Ds). Characterized by thick, rough, darkened, and sometimes red skin, which is often accompanied by neurological problems including depression, anxiety, irritability, dementia, and an inability to concentrate.

Vitamin C deficiency

Causes scurvy, a deadly condition characterized by bleeding gums, skin irritations, bruising, and poor wound healing. Cases are usually found in malnourished alcoholics, homeless individuals, and older adults on very restricted diets.

Body's synthesis of vitamin D

Cholesterol derivative is converted by ultraviolet light to previtamin D3 (or precalciferol) in the skin. After cholesterol derivative is converted to previtamin D3, this substance is converted in the skin to vitamin D3 (or cholecalciferol) which then diffuses in the blood and circulates to the liver.

Vitamin E roles

Eight different chemical compounds, a-tocopherol is the most biologically active. Is an antioxidant which plays a major role in the maintenance of protecting the fatty acids embedded in biological membranes from free radical-induced oxidative damage. Is enhanced by the presence of other antioxidant micronutrients such as vitamin C and selenium. Diets high in vitamin E are associated with decreased cancer risk.

Factors influencing ability to produce vitamin D

Environmental(people who live in places of less sunlight exposure), people with darker skin, and vitamin D3 production also decreases with age and deficiency is also more common in people who are obese

Folate role in pregnancy

Essential for the proper formation of the neural tube during prenatal development. This later develops into the spinal cord and brain. Increased folate has been shown to decrease the risk of a neural tube defect in some newborns. If neural tube does not close properly during prenatal development, it could result in exposed tissue in the spinal cord, brain, or both known as spina bifida.

Niacin (vitamin B3) role in body

Essential water-soluble vitamin involved in energy and vitamin C metabolism and synthesis of fatty acids and proteins. Is usually obtained through the diet, but can also be synthesized in the body from tryptophan, an essential amino acid. Niacin is needed to synthesize ATP and is a coezyme that is critical to redox reactions involved in energy metabolism. It's coenzyme form is also important for the synthesis of several important non-energy related compounds, such as fatty acids, cholesterol, steroid hormones, and DNA. It's coenzyme form is also needed for the metabolism of vitamin C and folate. Is also important for the maintenance, replication, and repair of DNA, and it may also play a role in protein synthesis, glucose homeostasis, and cholesterol metabolism.

Role of Thiamin (B1)

Essential water-soluble vitamin involved in energy metabolism and the synthesis of genetic material (DNA and RNA). Acts as a coenzyme, meaning that an enzyme will not function unless thiamin is present. As a coenzyme, thiamin plays a role in the synthesis of DNA, RNA, and triglycerides. Is also involved in ATP production.

Role of riboflavin (B2)

Essential water-soluble vitamin involved in energy metabolism, the synthesis of a variety of vitamins, nerve functions, and protection of biological membranes. Body uses riboflavin to produce two coenzymes needed to transfer oxygen or electrons from one molecule to another (Redox reaction). Necessary to also convert vitamin A and folate (a B vitamin) to their active forms, synthesize niacin (a B vitamin) from tryptophan (an amino acid), and to form vitamins B6 and K. Is also critical to the metabolism of several neurotransmitters, and is involved in reactions that protect biological membranes from oxidative damage.

Enrichment

Fortified foods that meet specified nutrient levels suggested by the US FDA. Fortification of a select group of foods with specified levels of B vitamins, thiamin, niacin, riboflavin, folate, and the mineral iron.

Dietary sources of pantothenic acid

Found in a diverse array of foods, including mushrooms, organ meats, and sunflower seeds. Dairy products, turkey, fish, and coffee are also good sources. Can be destroyed by high temperatures in cooking and bioavailability increases depending on the amounts needed by the body.

Dietary sources of Niacin

Found in a variety of foods such as liver, poultry, fish, tomatoes, beef, and mushrooms. Whole-grain foods, enriched cereal products, and other fortified foods can also provide niacin.

Dietary sources of Thiamin (B1)

Found in a wide variety of foods such as pork, peas, fish, legumes, soy-milk, enriched cereal products, and whole-grain foods.

Pantothenic Acid Deficiency

Found in almost every food so deficiencies are rare. Believed to cause a condition known as burning feet, which is characterized by a tingling sensation in the feet and legs, as well as fatigue, weakness, and nausea.

Dietary sources of vitamin K

Found in dark green vegetables such as kale, spinach, broccoli, and Brussels Sprouts. Can also be found in fish and legumes. Is destroyed by exposure to excessive light and/or heat.

Dietary sources of vitamin E

Found in plant and animal based foods, but is especially abundant in vegetable oils, nuts, and seeds. Is easily destroyed during food preparation, processing, and storage.

Dietary sources of vitamin B6

Found in variety of plant and animal foods such as chickpeas, fish, liver, potatoes, and chicken as well as fortified breakfast cereals and bakery products. Can be destroyed by extreme or prolonged heat and cold

Dietary sources of vitamin C

Fruits, vegetables, citrus fruits, peppers, papayas, broccoli, strawberries and peas, potato. Bio availability is generally high but its structure can be destroyed by heat and exposure to oxygen.

Bio availability of niacin

Greater in animal than plant based products. Plant based products can be treated with alkaline substances such as baking soda to increase bio availability.

Carotenoid compounds

Have similar structures to retinoids.Some can be converted to vitamin A such as provitamin A carotenoid. One of the most common forms of this is beta-carotene which the body converts to two retinal molecules. A carotenoid that cannot be converted to vitamin A is called a nonprovitamin A carotenoid.

Factors which can destroy thiamin (B1)

Higher temperatures during cooking

Deficiency of vitamin B6

Impedes heme production which lowers the concentrations of hemoglobin in red bloods cells causing microcytic, hypochromic anemia. This results in red blood cells that are small and light in color. This can diminish the red blood cells ability to deliver oxygen to tissues, which can impair ATP production. It also causes cheiolosis, glossitis, somatitis, and fatigue. Signs and symptoms are similar to riboflavin deficiency.

Vitamin A role in body

Important for health of the eye's outermost tissue layer the cornea and especially important to vision in low-light environments. Also play a role in cell differentiation, the process by which a nonspecialized, immature cell type becomes mature. It is also critical for growth and reproduction, and has a variety of immunological responses. Which include the maintenance of protective barriers, production of immune cells, and preformed vitamin A is also essential for healthy bones.

Vitamin D deficiency

In infants and children this can result in improper bone mineralization known as rickets. Causes slow growth and characteristically bowed legs or knocked knees. Can also cause the breast bone to stick out and rib cage to become narrow, resulting in cardiac and respiratory problems. In adults this can cause osteomalacia, where bones become soft and weak. Symptoms include diffuse bone pain and muscle weakness, along with increased risk of fracture. It can also result in demineralization of previously healthy bone, leading to osteoporosis which commonly occurs in the elderly population.

Bioavailability of water-soluble vitamins

Influenced by nutritional status, other nutrients and substances in foods, medications, age, and health status. Absorbed in small intestine and to a lesser extent the stomach. Circulated in the blood and transported from the gastrointestinal tract directly to the liver.

Biotin deficiency

Is uncommon but can be caused by genetic disorders and conditions that impair intestinal absorption. Smoking can also increase risk. Signs and symptom are depression, hallucinations, skin irritations, infections, hair loss, poor muscle control, seizures and developmental delays.

Measurement of niacin

Measured through niacin equivalent (NE) which looks at the combined amounts of niacin and tryptophan in a given food.

Pantothenic acid (Vitamin B5) role in body

Nitrogen-containing water-soluble vitamin which acts as a coenzyme in a variety of metabolic reactions, especially those involved in ATP. Acts as a coenzyme in the metabolism of glucose, amino acids, and fatty acids. Is also critical for the synthesis of many important compounds such as heme, cholesterol, bile, phospholipds, fatty acids, and some of the reproductive hormones.

Fortification

Nutrients added during processing. Generally used to improve the nutritional value of processed foods.

Vitamin D3 metabolism

Occurs in liver and kidneys. Vitamin D3 is converted to 25-hydroxyvitamin D3 in the liver. This circulates in the blood to the kidneys where it is converted to 1,25 dihydroxyvitamin D3 the active form of vitamin D known as calcitrol.

Vitamin B6 toxicity

Occurs more frequently than other water-soluble vitamins due to relatively large amounts of pyridoxal phosphate being retained within the muscle and liver cells. Can cause severe neurological problems, such as difficulty walking and numbness in the feet and hands. Usually results from excessive intake of supplements.

Folate deficiency

Occurs most often in alcoholics, people with intestinal diseases, people taking certain medications, and the elderly. Severe deficiency causes megaloblastic macrocytic anemia. Causes cells (including red blood cells) to remain large and immature.

Bio availability of biotin

Often bound to proteins in food and when bound too tight it can be difficult to absorb. Avidin (protein found in egg whites) reduces biotin's bioavailability (egg white injury). Alcohol can decrease biotin absorption and high cooking temperatures can destroy biotins in food.

Dietary sources of folate

Organ meats, legumes, okra, and many green leafy vegetables such as spinach. A common form of folate called folic acid is rarely found in foods but is oten in vitamin supplements and is added to fortified foods, therefore enriched foods are good sources of this vitamin. Folate is destroyed by excessive heat.

Dietary supplement

Product intended to supplement the diet that contains vitamins, minerals, amino acids, herbs or other plant-derived substances

Recommended vitamin B12 intake

RDA is 2.4 ug/day for adults. No ULs have been established

Carotenoid toxicity

Results from supplements usually. Been found to increase the risk of lung cancer in some people and can also cause carotenoids to accumulate in the skin turning it a yellow-orange color (hypercarotenodermia)

Cerebral beriberi (Wernicke-Korsakoff syndrome)

Thiamin deficiency characterized by abnomoral eye movements, poor muscle coordination, confusion, and short-term memory loss. In the US it is typically associated with alcoholism.

Wet beriberi

Thiamin deficiency characterized by severe edema in the arms and legs. Can cause an enlargement of the heart and respiratory problems which often result in heart failure.

Infantile beriberi

Thiamin deficiency found in babies breastfed by thiamin-deficient mothers, can also cause heart problems.

Dry beriberi

Thiamin deficiency in adults. Characterized by severe muscle wasting, leg cramps, tenderness, and decreased feeling in the feet and toes.

Retinoids (vitamin A)

Three compounds known as reinol, retinoic acid, and retinal. Retinol is the most biologically active and is synthesized in the body from retinal. Retiinoic acid can also be synthesized in the body from retinal, but retinoic acid itself cannot be converted to any other retinoid.

Vitamin K roles

Three compounds that have similar structures and functions. Found naturally in plant based foods in a form called phylloquinone. Another form, menaquinone, is porduced by bacteria in the large intestine. Third form is called menadione and is produced commercially. Vitamin K functions as a coenzyme in coagulation (blood clots). Clotting factors are activated by vitamin K which result in the production of fibrin, a protein which stops bleeding. It is also essential for the synthesis of proteins needed for bone and tooth formation.

Vitamin A deficiency

Uncommon in industrialized countries. Sometimes occurs in people with diseases that impair lipid digestion and absorption, such as cystic fibrosis. Is also prevalent in malnourished alcoholics with liver damage. In mildest form, VADD can cause night blindness. Severe forms can lead to xerophthalmia a condition whereby the cornea and other portions of the eye are damaged, leading to dry eyes, scarring, and even blindness. This is often accompanied by Bitot's spots which are white spots on the surface of the eye caused by accumulations of dead cells and secretions. Vitamin A deficiency can also cause hyperkeratosis whereby skin and nail cells overproduce the protein keratin causing them to become rough and scaly.

Vitamin E deficiency

Uncommon, cases only observed in infants fed formulas lacking sufficient amounts of vitamin E, people with genetic abnormalities, and people with diseases that cause fat malabsorption. Characterized by neuromuscular problems, loss of coordination, and muscular pain. Vitamin E can also damage the retina.

Retinol activity equivalents (RAE)

Unit of measure for the combined amounts of preformed vitamin A and provitamin A carotenoids in a food.

Recommended intakes for Vitamin A and carotenoids

Vitamin A intake are 900 and 700 ug RAE/day for adult men and women. UL of 3,000 ug RAE/day has been set for adults.

Vitamin B6 Roles

Water soluble vitamin that functions as a coenzyme, its pyridoxial phosphate form is involved in numerous chemical reactions related to the synthesis of nonessentail amino acids from essential amino acids. Is also essential for the production of some non-protein substances, such as heme and the neurotransmitters serotonin and dopamine. Exists in seven known forms, but the most common are pyridoxine, pyridoxal, pyridoxamine, and pyridoxlal phosphate.

Roles of vitamin B7 (biotin)

Water-soluble vitamin obtained from the diet and biotin producing bacteria in the large intestine. Critical component of several coenzymes involved in energy metabolism pathways. Shift bicarbonate subunits from one molecule to another. Also serves several functions related to gene expression, cell growth, and development.

Vitamin C (ascorbic acid)

Water-soluble vitamin that function as an antioxidant in the body. It's ability to reduce other atoms and molecules can increase the bioavailability of other essential nutrients such as iron, copper, and chromium. Some research also suggests that consuming adequate diet of vitamin C can prevent the risk of certain diseases by benefiting the immune system.

Vitamin B12 (cobalamin) roles in body

Water-soluble vitamin which is essential for ATP production and aids folate in amino acid metabolism. Is involved in the production of methionine (amino acid) which is essential for single carbon transfers and aids folate in amino acid metabolism. Cobalamin contains the trave element cobalt and several nitrogen (or amine) groups.