chapter 15
some scientists recommend that people expose their hands, face, and arms to UV light at least 2 or 3 times a week for __ to __ minutes. Individuals with dark skin may need sun exposure of __ minutes or more
- 10,15 - 30
As a component of ___ and ____ phosphate, phosphorus is critical to ____ production and storage
- ATP - creatine - energy
Magnesium also is needed for _____ synthesis. It also is important for nerve transmission, heart and smooth muscle _____, and ________ metabolism.
- DNA and RNA - contraction - glucose and insulin
phosphorus - part of _____, _____ in cell membranes, and numerous enzyme and cellular ____. - Many hormones depend on _____for their activation. - Phosphorus also helps regulate ______ in the body.
- DNA and RNA, phospholipids, message system - phosphorylation - acid-base balance
- _____ is fortified with vitamin A, as are fat-free, low-fat, and reduced fat milks. - About __% of the vitamin A in the typical North American diet comes from animal (preformed vitamin A) sources, whereas plant-based carotenoids (provitamin A) provide most of the vitamin A in the diets of poor people in other parts of the world
- Margarine - 70
In the cell nucleus, retinoids bind to 2 main families of retinoid receptors . These receptors called ______ bind to specific DNA sites (called retinoic acid response elements) that regulate the formation of ______ (needed to copy genetic material from DNA) and the subsequent formation of proteins through gene expression. Gene expression directs ______—the process in which stem cells develop into specialized cells with unique functions in the body
- RXR and RAR - messenger RNA - cell differentiation
The most active form of the vitamin E is _____-tocopherol. This is the form found in some foods and in varying amounts in vitamin supplements. ____-tocopherol is a potentially beneficial form of vitamin E found in many vegetable oils.
- alpha - gamma
Vitamin A (as _____) is needed in the retina of the eye to turn visual light into nerve signals to the brain. The sensory elements of the retina consist of the rods and cones. ____ are responsible for the visual processes that occur in dim light, translating objects into black-and-white images and detecting motion. ___ are responsible for the visual processes occurring under bright light, translating objects into color images.
- retinal - rods - cones
North America, milk is generally fortified with __ μg (400 IU) of vitamin D per quart.
10
The 1st signs and symptoms of scurvy, the vitamin C deficiency disease, appear after about __ to __ days on a diet free of vitamin C and include fatigue and pinpoint hemorrhages around hair follicles
20, 40
Some research indicates that ___ mg/day is the highest amount needed to maximize the health benefits of vitamin C intake
200
The Upper Level for calcium is ____ mg/day for adults ages 19 to 50 and ____ mg/day for those over age 50. The UL is based on the potential for increased risk of developing ____ at higher intakes
2500, 2000 - kidney stones and hypercalcemia
Upper Level for phosphorus in adulthood is _____ g/day, based on the risk of developing a high blood concentration
3,4
UL magnesium
350 mg/day
Acquired immunity develops over time as the body "learns" to recognize specific molecules as foreign, or "non-self," cells (antigens). ______ are typically large, foreign proteins.
Antigens
White blood cells, part of the body's immune defenses, contain the highest vitamin _ concentration of all body constituents. may protect against the oxidative damage associated with cellular respiration
C
degree of excretion, regulated by ___ (like calcium) and another hormone, FGF23, produced in bone osteocytes, is the primary mechanism by which blood phosphorus level is regulated
PTH
nutritionists thought this ratio of calcium to phosphorus contributed to mild hyperparathyroidism and bone loss. However, it is now thought that elevated ___ and bone loss occur in response to not meeting calcium needs (as can occur when soft drinks are substituted for milk and other calcium sources), rather than the ratio of calcium to phosphorus in the diet.
PTH
_________ also permits calcium and phosphorus to be "withdrawn" and used for other functions when dietary intake is insufficient.
Remodeling
minerals used to synthesize enzymes critical to antioxidant function
Selenium and zinc
fatty fish (e.g., sardines, mackerel, herring, and salmon), cod liver oil, fortified milk, and some fortified breakfast cereals
best food sources of vitamin D
Vitamin D is excreted primarily through ___ that is lost in the feces. Small amounts of vitamin D also are excreted in the ___.
bile - urine
Retinoic acid can enter the _____ directly for transport to the liver. Carotenoids also can enter the bloodstream directly; however, this occurs to a lesser extent
bloodstream
when blood levels of calcium and phosphorus start to fall, vitamin D (with PTH from the parathyroid gland) can release these minerals from ____ to restore blood levels
bone
Recent data from the European Prospective Investigation into Cancer and Nutrition Cohort (EPIC) and the Nurses' Health Study suggest a possible link between blood levels of beta-carotene and alpha-carotene and a decreased risk of ____ cancer. Studies of diets that contain high amounts of the carotenoids lutein and zeaxanthin suggest that they may help protect against age-related_______.
breast - macular degeneration
A collagen molecule is like a 3-stranded rope—it consists of 3 polypeptide chains wound together to form a triple helix. Vitamin _ is needed to get the 3 strands in the right shape to form the triple helix.
c
obtained from the diet, are the main minerals in bone
calcium and phosphorus
critical to normal bone structure
calcium, phosphorus, magnesium, and fluoride
Both calcium and dairy products may protect against the development of ____ cancer
colon
Vitamin A is especially important in maintaining normal differentiation of the cells that make up the structural components of the eye, such as the ____ (clear lens) and the _____ (rod and cone cells).
cornea, retina
prevents the normal synthesis of collagen, thus causing widespread, significant changes in connective tissue throughout the body
deficiency of vitamin C
Vitamin C, also known as ascorbic acid, is involved in many processes in the human body, primarily as an
electron donor
signs of toxicity include nausea, vomiting, diarrhea, sweating, spasms, convulsions, and coma.
fluoride
_____ very unstable compounds that have 1 or more unpaired electrons. can be destructive to electron-dense cell components, such as cell membranes and DNA
free radicals
Vitamin E deficiency is characterized by the premature breakdown of red blood cells (hemolysis) and the development of
hemolytic anemia
Calcium and phosphorus form the latticelike crystal ___________, Ca10(PO4)6OH2, which binds to _______ fibers. This combination of materials allows bone to be resilient and strong
hydroxyapatite - collagen
. In the liver, vitamin D is ______ (the addition of -OH) on carbon 25, converting it to 25-OH _____. This inactive form circulates in the blood for many weeks and serves as an additional storage pool of vitamin D
hydroxylated - vitamin D3 (calcidiol)
A medical condition known as ______ can cause persistently elevated blood calcium.
hyperparathryoidism
n addition to being a major component of bones and teeth, phosphorus is critical to the function of every cell in the body. As HPO42− or H2PO4−, phosphorus is the main
intracellular anion
Taking vitamin C with meals modestly facilitates the intestinal absorption of nonheme _____ (iron that is not in hemoglobin) because of the conversion of iron in the GI tract to ferrous iron (Fe2+).
iron
Although vitamin E is relatively nontoxic, excessive amounts can interfere with the role of vitamin _ in blood clotting. This causes insufficient clotting and a risk of ______.
k - hemorrhaging
The liver repackages the vitamin E from the chylomicron remnants with other _____ (VLDL, LDL, and HDL) for delivery to body tissues
lipoproteins
When vitamin D (either D3 synthesized in the skin or D2 consumed in food or supplements) enters the general circulation, it is bound to a vitamin D-binding protein for transport to muscle or adipose cells for storage or to the ______.
liver and kidneys
Retinoic acid also is necessary for the production, structure, and normal function of epithelial cells in the_______, as well as in many other systems. It is important for the formation and maintenance of mucus-forming cells in these organs.
lungs, trachea, skin, and GI tract
Over the last decade, there has been increased interest in a carotenoid pigment found in tomatoes, called ______. Much of this interest developed when scientists observed that men with greater intakes of tomato products and higher blood levels of lycopene had a reduced risk of prostate cancer
lycopene
Research suggests that diets high in magnesium rich foods may help protect against _____ and diabetes by improving insulin action
metabolic syndrome
When blood calcium falls, the _____ gland releases parathyroid hormone. This hormone raises blood calcium levels by increasing the kidneys' ______ of calcium so that urinary calcium decreases. Parathyroid hormone also helps increase calcium absorption indirectly by promoting the synthesis of ____ in the kidneys. parathyroid hormone often works in conjunction with calcitriol to release calcium from ____
parathyroid - reabsorption - calcitriol - bones
in lipid rich areas of the body, free radicals can initiate a chain of reactions known as peroxidation. Lipid peroxidation reactions break apart fatty acids and create lipid ______ (also called reactive oxygen species because they contain oxygen radicals). The chain of reactions continues to break apart fatty acids until 2 free radicals pair and _____ each other.
peroxyl radicals - stabilize
- Milk, cheese, meat, bakery products, and cereals - Bran, eggs, nuts, and fish
phosphorus
include anorexia, weight loss, weakness, irritability, stiff joints, and bone pain.
phosphorus deficiency
is rare, but a chronic deficiency can contribute to bone loss, decreased growth, and poor tooth development.
phosphorus deficiency
The amount of vitamin C that is stored varies widely by tissue. High concentrations are found in the ______. The lowest concentrations are in the blood and saliva.
pituitary and adrenal glands, white blood cells, eyes, and brain
nonspecific symptoms, including fatigue, irritability, gum bleeding, and joint and muscle pain. Alcoholics, those with poor diets, and smokers are at greatest risk.
poor vitamin C status
Ascorbic acid, by donating an electron to the oxidized iron, keeps the iron in its ______ ferrous form. This, in turn, allows enzymatic action to continue.
reduced
No Upper Level is set for carotenoids because vitamin A toxicity results only from excess intakes of ______
retinoids
Vitamin A and its related analog forms (all-trans-retinoic acid [topical tretinoin, or Retin-A®] and 13-cis-retinoic acid [oral isotretinoin, or Accutane®]) are used to treat various skin disorders, such as acne and psoriasis. However, these analogs are ______ in humans and have caused spontaneous abortion and birth defects
teratogenic
Unlike many of the other trace minerals, absorption is not affected by the body's stores, and absorption does not play a role in maintaining homeostasis. Selenium balance is achieved primarily through _____ excretion, rather than intestinal absorption
urinary
Although vitamin A is not readily excreted by the body, the primary means of excretion is via ____. Carotenoids are excreted via ___ that is eliminated with feces.
urine - bile
critical for maintaining the health of these physical barriers
vitamin A
several population groups are considered at risk. Impoverished and older adults, people with alcoholism or liver disease (which limits vitamin A storage), and individuals with severe fat malabsorption, which may develop in gluten-sensitive enteropathy (celiac disease), chronic diarrhea, pancreatic insufficiency, Crohn disease, cystic fibrosis, and AIDS, may develop
vitamin A deficiency
Vitamin D occurs in 2 forms—________. Vitamin __ occurs naturally in foods and is the form used to fortify foods and in supplements. Vitamin __ is the form synthesized in the skin during exposure to sunlight.
vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) - D2 - D3
The next stop is the kidney, the principal site for the production of 1,25(OH)2 ______. This is the active form of the vitamin that, as needed, binds to specific vitamin D receptors in target tissues to induce vitamin D actions
vitamin D3, also known as calcitriol
citrus fruits, peppers, and green vegetables - only orange juice can be considered an excellent source of
vitamin c
required for the absorption of both calcium and phosphorus and helps regulate their concentrations in the blood; thus, it is involved in bone metabolism.
vitamin d
impair immune function and cause neurological changes in the spinal cord and peripheral nervous system
vitamin e deficiency
Females, especially those in the peak bone-building years from ages 9 through 18 years and those over the age of 71, have the lowest intakes. Only __% of younger females and __% of older women meet the RDA for calcium, even when both dietary and supplemental sources of calcium are considered. Older men, especially those over age 70, do not fare as well, with nearly __% not reaching the RDA
- 15 - 39 - 70
A person with a low circulating concentration of 25-OH vitamin D3 should take at least __ to __ μg (800-1000 IU) of vitamin D each day until the concentration reaches the normal range. After blood concentrations are adequate, __ μg (400 IU/day) of supplemental vitamin D should be sufficient for most people
- 20, 25 - 10
Small increases in bone mass continue between __ and __ years of age. Genetic background controls up to __% of the variation in the peak bone mass ultimately built
- 20, 30 - 80
Adults absorb about __ to __% of the calcium present in the foods they eat, but during periods of growth when the body needs extra calcium—such as infancy and pregnancy—absorption levels might reach __%. ____ generally absorb the least calcium
- 25, 30 - 75 - postmenopausal women
About __ to __% of the magnesium consumed is absorbed, but absorption efficiency can rise to about ___% when intakes are low. Magnesium is absorbed in the small intestine by both____
- 30, 40 - 80 - passive and active absorption
To support the diverse functions of vitamin D, some researchers estimate that the body requires approximately _____ to ____ IU (75-100 μg) of vitamin D daily to maintain optimal blood levels of 25-OH vitamin D3. However, typical inputs from UV exposure (_____ IU), food sources (___-___ IU), and dietary supplements (___ IU) often provide 2400 IU daily or less for the average individual. Thus, an oral intake of approximately 1000 to 4000 IU daily might be necessary to maintain optimal vitamin D status in people who have limited sun exposure
- 3000, 4000 - 2000 - 150-200 - 200
magnesium RDA: DV:
- 400 mg/day for men 19 to 30 years of age and 310 mg/day for women 19 to 30 years of age - increase slightly (10 to 20 mg/day) beyond age 30 - 420 mg
selenium rda dv ul
- 55ug/day -55 - 400
Adding fluoride to the public water supply adjusts the fluoride level to __ ppm or __ mg/liter; this concentration is considered safe and optimal for the prevention of dental caries
- 0.7 - 0.7
on average, North Americans require approximately __ μg (400 IU) of vitamin D daily. To meet these estimated needs, the IOM raised the RDA to __ μg/day (600 IU/day) for individuals 1 to 70 years old and __ μg (800 IU) for adults over age 70 years. - Daily Value used on food and supplement labels is
- 10 - 15 - 20 - 20
Acute toxicity is caused by the ingestion of 1 very large dose of vitamin A or several large doses taken over a few days (about ____ times the RDA). The effects of acute toxicity include GI tract upset, headache, blurred vision, and poor muscle coordination. Once the dosing is stopped, the signs disappear. Extraordinarily large doses of ____ mg in children and __ g in adults can be fatal.
- 100 - 500, 10
calcium RDA: Daily value:
- 1000 mg/day, but it increases to 1200 mg/day for women over age 50 and men over age 70. - adolescents need 1300 mg/day - 1300 mg
vitamin d Upper Limit to _____ to _____ IUs per day for infants and children up to 8 years of age and ____ IUs per day for individuals 9 years of age and older.
- 1000, 3000 - 4000
Yeast breads, rolls, crackers, and other foods made with dairy products are other contributors. Kale, collards, turnip greens, broccoli, almonds, and calcium-fortified fruit juices, soy milk, rice milk, and breakfast cereals supply this mineral. The tiny, soft bones present in canned fish, such as salmon and sardines, provide
calcium
- Dairy products, such as milk and cheese, provide a rich supply of bioavailable ______ and make up just over ____ the calcium in U.S. diets
calcium - 1/2
When a skeletal muscle fiber is stimulated by a nerve impulse from the brain, ______ ions are released from ____ stores within the muscle cells. The resulting increase in the concentration of calcium ions in a muscle cell, along with sufficient ATP, permits the _____ proteins to slide along each other
calcium - intracellular - contractile
The tooth consists of a hard, yellowish tissue called _____, which is covered with enamel in the crown and cementum in the root
dentin
studies indicate that diets high in carotenoid rich fruits and vegetables may decrease the risk of certain
eye diseases, cancers, and cardiovascular disease
Calcium ions participate in several reactions in the cascade that leads to the formation of _____, the main protein component of a blood clot.
fibrin
tea, seafood, and seaweed provide the greatest amounts of dietary
flouride
s part of the immune system's arsenal against invading pathogens, white blood cells (leukocytes) generate _____to destroy bacteria, viruses, and other agents that cause infections.
free radicals
vitamin D plays an important role in _____ in most tissues, which may decrease the risk of many chronic illnesses, including diabetes; colon, prostate, and breast cancer; cardiovascular disease; and autoimmune diseases, such as multiple sclerosis.
gene control and cell cycle regulation
The recommendation is based on the amount of vitamin E needed to prevent a breakdown of red blood cell membranes, a process called ______. The 15 mg allotment is approximately equivalent to 22 IU of a natural source or 33 IU of a synthetic source of vitamin E.
hemolysis
osteoporosis bones most likely to break
hip, the wrist, and the vertebrae in the spine
Additionally, vitamin D may decrease the risk of certain types of ________, such as multiple sclerosis, and offer protection against diabetes, hypertension, dementia, and certain cancers
infections and autoimmune diseases
is found in chlorophyll. Thus, some of the richest sources of _____ are plant products, such as green leafy vegetables, broccoli, squash, beans, nuts, seeds, whole grains, and chocolate - Animal products, such as milk and meats
magnesium
toxicity of ____ can occur during kidney failure. cause weakness, nausea, slowed breathing, eventual malaise, coma, and death.
magnesium
The vitamin E content of a food depends on harvesting, processing, storage, and cooking because vitamin E is highly susceptible to destruction by
oxygen, metals, light, and heat, as in deep-fat frying
Because a dietary source is not required if synthesis is adequate to meet needs, vitamin D is more correctly classified as a "conditional" vitamin, or ____
prohormone
Specifically, vitamin C works with the metalloenzymes prolyl and lysyl hydroxylase to convert the amino acids _______ in collagen to hydroxyproline and hydroxylysine. These unusual amino acids (rarely found in other tissues) stabilize the collagen structure
proline and lysine
synthesis of vitamin D3 begins with a compound called _______, a precursor of cholesterol synthesis located in the skin. During exposure to sunlight, 1 ring on the molecule undergoes a chemical transformation, forming the more stable vitamin D3 (cholecalciferol). This change allows vitamin D3 to enter the bloodstream for transport to the liver and kidneys, where it undergoes conversion to its bioactive form _____.
- 7-dehydrocholesterol - calcitriol
Adults absorb up to __% of dietary phosphorus. Absorption occurs mainly in the upper small intestine by both _____. The active hormone 1,25(OH)2 vitamin _ enhances absorption.
- 70 - active transport and diffusion - d
From a 1000 mg calcium intake, only about 300 mg are absorbed. The remaining ____ mg are excreted in the feces. To maintain calcium balance, approximately ____ mg of calcium are excreted daily via the kidneys, skin, and secretions, as well as intestinal cells sloughed off in the feces.
- 700 - 300
Approximately __% of the phosphorus in the body is found in bones and teeth as calcium phosphate (hydroxyapatite). The remainder of the phosphate is found in every cell in the body and in the _____ fluid as PO42−. Phosphorus is excreted by the ____.
- 80 - extracellular - kidneys
Over __% of the body's vitamin A stores are found in the liver, with small amounts in adipose tissue, kidneys, bone marrow, testicles, and eyes. Normally, the liver stores enough vitamin A in the form of retinyl esters to last for several ___ to protect against vitamin A deficiency
- 90 - months
Vitamin A rda dv ul
- 900 μg Retinol Activity Equivalents (RAE) per day for adult men and 700 μg RAE per day for adult women - 900 μg - 3000ug
vitamin _ is critical to the maintenance of the physical barrier provided by skin and epithelial tissue, and vitamin _ helps protect white blood cells
- A - C
_____, the most active form of vitamin D, has several important functions.Its most recognized function is its hormone like role in maintaining the body's concentration of _____
- Calcitrol - calcium and phosphorus
fluoride is recognized for its beneficial role in supporting the _____ of calcium and phosphorus in teeth and bones and in protecting against the development of _____
- deposition - dental caries
______ bones are calcium's major functions in the body . Calcium also is required for __________
- developing and maintaining - blood clotting, the transmission of nerve impulses, muscle contraction, and cell metabolism
Calcium absorption is reduced when there is reduced secretion of stomach acid, chronic ____, or large intakes of phytic acid in fiber, oxalic acid, dietary phosphorus, and polyphenols, such as tannins in tea. ___ malabsorption, which occurs with some intestinal disorders, also can reduce calcium absorption because calcium binds with fatty acids, forming unabsorbable soaps in the intestinal lumen.
- diarrhea - fat
Spongy bone is abundant at the _____ of the long bones, inside the spinal vertebrae, and inside the flat bones of the pelvis. Spongy bone is where most _______ and other minerals move into and out of bone.
- ends - calcium
Calcium in the bloodstream is transported to cells either as ____ calcium or bound to ___. The skeleton and teeth hold more than __% of the body's calcium.
- free ionized - proteins - 99
By donating electrons to ________ (molecules with unpaired electrons), vitamin C _________ free radicals, thereby protecting various cellular compounds (including DNA, proteins, and lipids) from free radical induced-damage.
- free radicals - inactivates
During the development of teeth and bones, fluoride forms _______. These crystals provide greater resistance (than typical hydroxyapatite crystals) to _____ in the mouth that can erode tooth enamel. Fluoride in the blood contributes to fluoride in the ____, which promotes the remineralization of enamel lesions and reduces the net loss of minerals from tooth enamel.
- hydroxyfluorapatite crystals - bacteria and acids - saliva
vitamin D can cause an overabsorption of calcium and _____. Excess blood calcium, in turn, leads to deposits of calcium in the _________; anorexia; nausea; vomiting; bone demineralization; weakness; joint pain; and kidney dysfunction.
- hypercalcemia - kidneys, heart, and lungs
Vitamin A deficiency also produces skin changes, referred to as follicular _____. Keratin, the normal component in the outer layers of the skin, protects the inner layers and reduces water loss through the skin. During severe vitamin A deficiency, keratinized cells, which are normally present only in the ______, replace the normal mucus-forming epithelial cells in the underlying skin layers. Hair follicles become plugged with keratin, giving skin a dry, rough, sandy texture
- hyperkeratosis - outer layers
In an entirely different process, nerve impulses develop spontaneously if insufficient calcium is available, leading to what is called ______ . This condition is characterized by muscle spasms because the muscles receive continual nerve stimulation. Inadequate _____ hormone release or action is the typical cause of hypocalcemia (low blood calcium)
- hypocalcemic tetany - parathyroid
Retinoids perform various functions in the body. They help protect the body through their roles in the ____ system and maintenance of the _____. They also are critical to normal growth and development, _______
- immune - epithelium - cell differentiation, and vision.
Some studies suggest that vitamin D helps regulate ____ function and the secretion of several ____ (insulin, renin, PTH). Although the exact role of vitamin D in many tissues is not fully known, some scientists believe it may be involved in _______
- immune - hormones - cell cycle regulation
It is likely that selenium also plays an important role in _____. Scientists believe that selenium may prevent _____ disease by inactivating a virus linked to its development. Additionally, selenium may decrease the risk of _____, or other cancers, although studies have provided conflicting results
- immune function - Keshan - prostate, breast, lung
______ helps stabilize ATP by binding to the ______ of this molecule. In fact, magnesium is required by more than 300 enzymes that utilize ATP, including those required for energy metabolism, muscle contraction, and protein synthesis. A _____-dependent enzyme system pumps sodium out of cells and potassium into cells
- magnesium - phosphate groups - magnesium
As an electron donor, vitamin C has a cofactor role for several _______ and has antioxidant defense functions. Metalloenzymes contain metals, such as iron, copper, or zinc (usually as an ion), as a part of their structures. When a metalloenzyme catalyzes a reaction, the metal ion becomes _______.
- metalloenzymes - oxidized
Most of the selenium in foods is bound to the amino acids _________ (as selenomethionine) and_________ (as selenocysteine). Both forms are well absorbed in the small intestine, with absorption ranging from __ to ___% of dietary intake.
- methionine, cysteine - 50, 100
Likewise, high concentrations in _____, a type of white blood cell, may be for protection against the free radicals produced during immune functions. Another important antioxidant function of vitamin C is to regenerate the active form of vitamin _ and make it function more effectively.
- neutrophils - E
Another vital defense system used to prevent the overproduction of reactive species in cells is provided by a family of 3 enzymes known as ______. These enzymes are important in eliminating superoxide radicals that form when ____ reacts with other compounds
- superoxide dismutase (SOD) enzyme - oxygen
selenium deficiency is associated with changes in _______ metabolism and a possible increased risk of certain cancers. Selenium deficiency also is associated with the development of Keshan disease, a disease characterized by insufficient _______.
- thyroid hormone - cardiac function
Vitamin E is a family of 8 naturally occurring compounds—4 _____ (alpha, beta, gamma, delta) and 4 tocotrienols (alpha, beta, gamma, delta)—with widely varying degrees of biological activity. Vitamin E has a long ____ chain tail attached to a _____structure
- tocopherols - carbon - ringed
Vitamin C is required for the synthesis of many important biological compounds. These compounds include the amino acid ___, the hormone ______, the fatty acid transport compound ______, and the neurotransmitters ______
- tyrosine - thyroxine - carnitine - norepinephrine, ephinephrine, and serotonin.
calcium absorption is most efficient in the ______ part of the small intestine because its slightly _____ pH helps keep the calcium dissolved in its ionic form (Ca2+). Intestinal contents become more alkaline as they pass through the intestine; thus, calcium absorption decreases at the terminal end of the small intestine and in the colon, although some still occurs via _____ diffusion
- upper - acidic - passive
When blood calcium levels rise too high, less parathyroid hormone is released. This causes ______ calcium excretion to increase. The synthesis of ______ also decreases, causing a drop in calcium absorption. In addition, the thyroid gland secretes the hormone _____, which blocks calcium loss from bones.
- urinary - calcitriol - calcitonin
Flouride: For infants up to 6 months of age, the Adequate Intake is ___ mg/day. This increases to ___ mg/day for infants 6 to 12 months of age and ranges from __ to _ mg/day for young children and adolescents
-0.01 - 0.5 - 0.7-3
Flouride AI:
-3 mg/day for adult women and 4 mg/day for adult men
nearly __% of adults consume less than the EAR for vitamin C. CDC data from 2003-2006 indicate that about _% of persons age 6 and older have vitamin C serum concentrations indicating a deficiency and another __% have concentrations that are low
40 - 6 - 10, 12
Vitamin C, the least stable vitamin, is easily lost in storage, processing, and cooking. Normal cooking can decrease vitamin C content up to __%, and potatoes stored for 5 months lose __% of their vitamin C content. This vitamin is very unstable when in contact with________.
40, 50 - iron, copper, and oxygen.
Food additives, such as monosodium phosphate (emulsifier), monocalcium phosphate (jelling agent/dough conditioner), and nutrients used for fortification (e.g., iron phosphate), also contribute as much as ___ mg per day of phosphorus to the diet.
400
Absorption is best when doses of calcium do not exceed ___ mg and they are taken with or just after meals because the stomach acid produced during digestion improves absorption
500
Vitamin C needs also increase in burn and trauma patients because collagen synthesis increases greatly when rebuilding new tissue. These patients often are provided an extra ___ to ____ mg of vitamin C per day.
500, 1000
phosphorus RDA: DV:
700mg/day 1250mg
Following the consumption of foods containing vitamin D2, about __% of vitamin D2 is incorporated (along with other dietary fats) into ____ in the small intestine, absorbed, and transported to the liver by _____ through the lymphatic system
80 - micelles - chylomicrons
For many individuals, sun exposure provides __ to __% of the vitamin D3 required by the body. The production of vitamin D3 in the skin decreases by about __ % when one reaches the age of 70
80, 100 - 70
Vitamin E also differs from other fat-soluble vitamins in that it does not accumulate in the liver; instead, approximately __% of the vitamin E in the body is localized in adipose tissue.Vitamin E can be excreted via the ______.
90 - bile, urine, and skin
From studies of animals, scientists learned that vitamin _ is involved in the development of eyes, limbs, the cardiovascular system, and the nervous system.
A
include impaired wound healing, bone pain, fractures, and diarrhea. Psychological problems, such as depression, are common in advanced
scurvy
- seafood, meats, cereals, and grains - varies significantly in relation to the soil content where the plant was grown or the animal raised
selenium
toxicity include nausea, diarrhea, fatigue, hair loss, changes in nails, and impairment of sulfur and protein metabolism
selenium toxicity
Another important function of selenium is in _____ metabolism as a part of iodothyronine deiodinase enzymes.
thyroid
Deficiencies of vitamin _ and vitamin _ are the least common nutrient deficiencies in the U.S., occurring in less than 1% of the population
a,e
Several synthetic compounds with a chemical makeup similar to that of vitamin A (called analogs) have been used in topical and oral medications (e.g., Retin-A® and Accutane®) to treat
acne and psoriasis
beta-carotene may act as an ______ within tissues, thereby protecting them from free radical damage.
antioxidant
_____ are yellow-orange pigmented materials in fruits and vegetables, some of which are provitamins—that is, they can be converted into vitamin A. Of the 600 or more known carotenoids, only _______ can be converted to biologically active forms of vitamin A. Other carotenoids, such as lycopene, lutein, and zeaxanthin, are not converted into vitamin A and, thus, do not have vitamin A activity in humans
- Carotenoids - alpha-carotene, beta-carotene, and beta-cryptoxanthin
_____ also contribute significantly to dietary magnesium. Refined foods generally are low in magnesium, and the form of magnesium in multivitamins and mineral supplements (magnesium oxide) is ___ well absorbed.
- Coffee and tea - not
Some antioxidants, such as vitamin _, function in a lipid environment within cell membranes, whereas other antioxidants, such as vitamin _, work in the aqueous environment inside cells
- E - C
_______ generated during phagocytosis and neutrophil activation, although intended to kill bacteria or damaged tissue, also can damage the body's own immune cells. Vitamin _ may reduce this self-destruction through its antioxidant defense actions.
- Free radicals - C
_______ is a collective term for the biologically active forms of vitamin A. They are called preformed vitamin A because, unlike ______, they do not need to be converted in the body to become biologically active. Retinoids exist in 3 forms: ____ (an alcohol), ___ (an aldehyde), and _____. - retinoic acid _____ be converted back to the other forms
- Retinoids - carotenoids - retinol - retinal - retinoic acid - cannot
- found in liver, fish, fish oils, fortified milk, and eggs. - dark green and yellow-orange vegetables and fruits, such as carrots, spinach and other greens, winter squash, sweet potatoes, broccoli, mangoes, cantaloupe, peaches, and apricots
- Retinoids (preformed vitamin A) - provitamin A carotenoids
Dietary vitamin A activity is currently expressed in _______ (RAE) to account for the different biological activities of retinol and provitamin A caretenoids. One RAE is equal to 1 μg of retinol, ___ μg of beta-carotene, and __ μg of the other 2 provitamin A carotenoids (alpha-carotene and beta-cryptoxanthin)
- Retinol Activity Equivalents - 12 - 24
______ are important parts of the body's antioxidant network. ____ also contribute to antioxidant defenses
- Vitamin E, vitamin C, selenium, and beta-carotene manganese, copper, zinc
Collagen protein allows the skeleton to ______ (e.g., bone does not usually break when you jump), and the hydroxyapatite crystal makes bone _______ (e.g., bone does not bend or collapse when you jump).
- absorb impact - strong
The absorption of vitamin C occurs in the small intestine by _____ (for ascorbic acid) and by ________ (for dehydroascorbic acid). The efficiency of the absorptive mechanism decreases as intake increases. About __ to __% of vitamin C is absorbed at daily intakes between 30 and 200 mg, whereas the rate of absorption declines substantially with doses exceeding that amount. Excretion by the _____ rises as dietary intake increases
- active transport, facilitated diffusion - 70, 90 - kidney
vitamin c rda dv ul
- adult men is 90 mg/day; for adult women, it is 75 mg/day - 90mg - 2g/day
pregnant women should limit their intake of these foods and, if taking supplements, should check that much of the supplemental vitamin A is in the form of ______. The FDA recommends that women of childbearing age limit their intake of preformed vitamin A to ___% of the Daily Value
- beta-carotene - 100
vitamin C is involved in the conversion of cholesterol to ____ and biosynthesis of the hormones_____. In each case, vitamin C keeps the copper or iron in the metalloenzyme in the reduced state (as Cu+ or Fe2+).
- bile acids - corticosteroids and aldosterone
About half of the magnesium is found in _____, and the rest is stored in other tissues, such as muscles. The ____ primarily regulate blood concentrations of magnesium and are able to reduce magnesium loss into the urine when blood magnesium is low
- bones - kidneys
The skeleton will not mineralize normally without adequate calcium and phosphorus in the blood for deposition in bone. This causes the bones to weaken and ____under pressure. When these effects occur in the growing bones of a child, this vitamin D deficiency disease is called _____. The signs of rickets include _____ head, joints, and rib cage; a ____ pelvis; and ____legs.
- bow - rickets - enlarged - deformed - bowed
Calcium ions help regulate metabolism in the cell by participating in the _____ system. Each calmodulin binds __ calcium ions. When calcium enters a cell (often because of hormone action) and binds to the protein calmodulin, the resulting calcium-calmodulin complex activates many intracellular enzymes, including an enzyme that initiates the breakdown of ____
- calmodulin - 4 - glycogen
The most widely used supplements are calcium _____ (the form in calcium-based antacid tablets) and calcium ____. The amount of calcium in a supplement depends on the form used. Calcium carbonate supplements have the highest proportion of calcium (__%), whereas those with calcium gluconate have the least (_%).
- carbonate - citrate - 40 - 9
The outer, dense shell of bone is _______ (also known as cortical bone); it makes up about ____% of the skeletal mass. The remainder is _________ (also known as trabecular bone), a hard, spongy network of rods, plates, and needlelike spines that add strength without much weight
- compact bone - 75 - spongy bone
Two of the superoxide dismutase enzymes require ______. One of these enzymes is located inside the cell (in the cytosol) and the other is outside the cell. The 3rd superoxide dismutase enzyme, found in the mitochondria, requires the mineral ____.
- copper and zinc - manganese
In the rods, 11-cis-retinal binds to a protein called ____ to form the visual pigment _____. The absorption of light catalyzes a change in the shape of 11-cis-retinal to all-____-retinal, causing opsin to ____ from all-trans-retinal. (The separation is a _______.) This leads to a cascade of biochemical events that trigger a change in the ion permeability of the photoreceptor cells and initiate a signal to the nerve cells that communicate with the brain's _____ center
- opsin - rhodopsin - trans - separate - bleaching process - visual
During times of growth, total _____ activity exceeds _______ activity, so we make more bone than we break down
- osteoblast - osteoclast
_______ are cells on the bone surface that dissolve bone (termed bone resorption) by releasing acid and enzymes. Their activity is stimulated by _________ hormone, often in conjunction with 1,25(OH)2 vitamin _. Osteoclasts are very active when a diet is deficient in ______—they release calcium from the bone so that it can enter the blood.
- osteoclasts - parathyroid - D - calcium
Vitamin D deficiency in adults is called _____, which means "soft bones." It is characterized by poor calcification of newly synthesized bone, resulting in fractures in the hip, spine, and other bones.Osteomalacia is most likely to occur in adults with_______.
- osteomalacia - kidney or liver disease
Once freed, carotenoids are absorbed primarily by ____ diffusion. Carotenoid absorption rates range from __ to ___% of intake. Inside intestinal cells, provitamin A carotenoids can be cleaved to form ____ or, to a lesser extent, retinoic acid. Retinal is then converted to _____
- passive - 5,60 - retinal - retinol
vitamin e Absorption occurs by____ and can vary from __ to __% of dietary intake. As with other fat-soluble nutrients, vitamin E must be incorporated into micelles in the small intestine, a process dependent on ______ enzymes. Once taken up by the intestinal cells, vitamin E is incorporated into _______ for transport in the lymph and eventually the blood.
- passive diffusion - 20,70 - bile and pancreatic - chylomicrons
The absorption of dietary fluoride occurs rapidly in the stomach and small intestine via _____. Overall, approximately ____% of fluoride consumed is absorbed. Absorbed fluoride is transported in the bloodstream and concentrated in_____.
- passive diffusion - 80 to 90 - teeth and the skeleton
Innate immunity, which is generally present at birth, includes ______that block access to the body (e.g., skin and epithelial tissue); ______ (e.g., hydrochloric acid produced by the stomach); physiological barriers (e.g., fever) that destroy or prevent the growth of invaders; and _____ that engulf and destroy invaders.
- physical barriers - chemical secretions - phagocytic cells
high blood concentrations of phosphorus (hyperphosphatemia) can cause calcium-phosphorus _____ to form in body tissues. Poor ______ function is the most common cause of hyperphosphatemia.
- precipitates - kidney
Worldwide, scurvy is associated with poverty. It is especially common in infants who are fed boiled milk (all forms of milk are poor sources of vitamin C) and not given a good food source of vitamin C or a supplement. Although scurvy is considered __in North America, poor vitamin C status is relatively ____, as mentioned previously.
- rare - common
Vitamin C, as a reducing agent, acts to keep the iron in the metalloenzymes in the _____ Fe2+ form required for enzyme action. Without vitamin C, _____ cannot be synthesized, and collagen is weak and fragile
- reduced - hydroxyproline and hydroxylysine
Without enough _____, mucus-forming cells deteriorate and are no longer able to synthesize mucus. The eye, especially the cornea, is adversely affected by the loss of mucus because mucus helps keep the eye surface moist and washes away dirt particles that settle on the eye. This leads to the development of ____ (abnormal dryness of the conjunctiva of the eye). _____ (foamy, gray spots on the eye consisting of hardened epithelial cells) also appear as vitamin A deficiency worsens. These conditions often progress to ______ (softening of the cornea) and scarring. This sequence of changes in the eye—collectively known as ______—causes irreversible blindness in millions of people worldwide.
- retinoic acid - conjunctival xerosis - Bitot's spots - keratomalacia - xerophthalmia
When vitamin A (as a retinoid) is released from the liver into the bloodstream, it is bound to a _______ (RBP) . Synthesis of RBP depends on having adequate amounts of _______. In the bloodstream, retinol-binding protein is bound to another protein called ______ (commonly known as prealbumin). In contrast, when carotenoids are released from the liver, they are carried by _____ and are taken up into cells by specific apoprotein receptors
- retinol-binding protein - retinol, protein, and zinc - transthyretin - lipoprotein
When the retinol in the blood is insufficient to replace the retinal lost during the visual cycle, the rods in the retina regenerate _____ more slowly. The resulting _______ is a common early symptom of vitamin A deficiency, as discussed earlier.
- rhodopsin - night blindness
During exposure to bright light, the rod's _____ is completely activated and cannot respond to more light. To keep the visual process functioning, all-____-retinal must eventually be converted back to 11-____-retinal. This regeneration occurs within several minutes. The 11-cis-retinal then moves back to the photoreceptor cells, where it recombines with the ____, forming rhodopsin, and is ready for another visual cycle.
- rhodopsin - trans - cis - opsin
activity of glutathione peroxidase depends on the mineral ______ (the functional part of this enzyme). _____ also is important for the removal of hydrogen peroxide. This heme iron-dependent enzyme is found in the peroxisomes of cells.
- selenium - Catalase
inadequate supplies of ______ negatively affect antibody function. Poor vitamin _ status also has been linked with impaired immune function.
- selenium and zinc - E
The majority of the body's magnesium is located in the ______; with a role in _____, magnesium contributes to bone _______
- skeleton - calcium metabolism - structure and mineralization
highest concentrations of selenium are found in the liver, pancreas, muscle, kidneys, and thyroid. Within tissues, selenomethionine provides a "_______" of selenium, whereas selenocysteine serves as the ________ form of the mineral.
- storage pool - biologically active
In many nerves, the arrival of the impulse at the target site causes _____ ions from the extracellular medium to flow into nerve cells. The rise in calcium ions in the nerve triggers synaptic vesicles to release their store of ______. The released neurotransmitter then carries the impulse across the synapse to the _____ cells
-calcium - neurotransmitters - target
Preformed vitamin A is found in foods of animal origin as retinol and retinyl ester-compounds (retinol attached to a fatty acid). Retinyl esters don't have vitamin A activity until the retinol and fatty acid are ______ in the intestinal tract. This process requires bile and pancreatic lipase enzymes. Up to __% of retinol is absorbed into the cells of the small intestine via specific carrier proteins. After absorption, a fatty acid is attached to ___ to form a new retinyl ester. These retinyl esters are packaged into ______ before entering the lymphatic circulation
-separated - 90 - retinol - chylomicrons
To minimize the risk of fluorosis, an Upper Level has been set at __ mg/kg body weight/day (0.7 to 2.2 mg/day) for infants and children up to 8 years of age. The Upper Level for children over age 8 and for adults is __mg/day
0.1 - 10
selenium toxicity (selenosis) has been observed with intakes as low as _ to _ mg daily taken over many months.
1,3
most of the adult skeleton is replaced about every __ years
10
vitamin E rda DV UL
15 mg/day - 15 - 1000mg
Adults consume, on average, only ___ of the RDA for vitamin E each day
2/3
Women experience even greater bone loss when estrogen levels fall in menopause because estrogen inhibits bone breakdown by decreasing osteoclast activity. Women can experience an additional __% loss of bone in the first 5 to 7 years following menopause
20
Fewer than __% of adults meet the RDA for magnesium
25
However, beginning in middle age, osteoclast activity generally becomes more dominant in both men and women. This can result in a total loss of about __% of bone, depending on how long the person lives
25
Selenium is a component of at least __ different enzymes and proteins in the body. One of its most recognized functions is in the antioxidant defense network, as a part of _____ (GPx) enzymes, thioredoxin reductase enzymes, and selenoprotein P . As part of the antioxidant defense network, selenium helps prevent lipid ______ and cell membrane damage. Its ability to destroy highly reactive peroxyl free radicals spares vitamin _ for use in other antioxidant functions.
25 - glutathione peroxidase - peroxidation - e
A vitamin E molecule is "used up" during chain-breaking action and must be regenerated by reducing agents. Vitamin _, along with other compounds, aids in the regeneration of vitamin E to allow it to function again.
C
plant oils (e.g., cottonseed, canola, safflower, and sunflower oils), wheat germ, avocado, almonds, peanuts, and sunflower seeds. Products made from the plant oils—margarine, shortenings, and salad dressings—also are good sources
Good food sources of vitamin E
To protect itself, the body must be able to regulate free radical activity and avoid potentially damaging effects. This task is assigned to vitamin _ and other antioxidants, such as glutathione peroxidase, catalase, and superoxide dismutase
E
acts as an antioxidant, primarily in lipid rich areas of the body, and is 1 of the most effective mechanisms for stopping lipid peroxidation. By donating a hydrogen to lipid radicals, vitamin _ stops the peroxidation chain
E
may cause irritability, headache, kidney failure, kidney stones, and decreased absorption of other minerals
Excessive dietary calcium
_____ an enzyme located in the cytoplasm and mitochondria of cells, is important in catalyzing the breakdown of hydrogen peroxides and lipid peroxides.
Glutathione peroxidase
- slightly increase the risk of kidney stone formation and excess iron absorption, but only in those who are predisposed to form kidney stones and who have preexisting iron absorption disorders - give false results in medical tests for blood in the stool
High doses of vitamin C
______ also can cause a fall in PTH release, resulting in low blood calcium. The action of 1,25(OH)2 vitamin D also is blunted
Magnesium deficiency
an irregular heartbeat, sometimes accompanied by weakness, muscle spasms, disorientation, nausea, vomiting, and seizures. These symptoms may be related to abnormal nerve cell function caused by an impairment of sodium and potassium pumping.
Magnesium deficiency
help deactivate oxidative compounds
Vitamin C, vitamin E, and beta-carotene (which can be converted to vitamin A)
Individuals at greatest risk of deficiency are those with fat malabsorption conditions, such as cystic fibrosis or Crohn disease, smokers, and preterm infants
Vitamin E Deficiency
Because of its roles as an antioxidant and in promoting normal immune function, a great deal of research has examined vitamin C's ability to prevent both _______. For cancer, the evidence is best for cancers of the mouth, esophagus, stomach, and lung, but not all studies are positive, and it is still not known if vitamin C, either as a dietary supplement or in the diet, provides protection.
cancer and heart disease
Vitamin E protects ________ integrity by neutralizing lipid peroxyl radicals n this bilayer and preventing lipid ______. In this way, vitamin E reduces _________ (damage to proteins, lipids, and DNA caused by free radicals) in the body.
cell membrane - peroxidation - oxidative stress
joint pain, loss of appetite, skin disorders, headache, reduced bone minerals, liver damage, double vision, hemorrhage, and coma. These symptoms occur with repeated intakes of at least 10 times the RDA guidelines.
chronic vitamin A toxicity
If vitamin A pools become depleted, the process of ______ is impaired, making it difficult to adjust to seeing in dim light, known as night blindness.
dark adaptation
vitamin A helps maintain the epithelium, a barrier that protects the body against the entry of disease pathogens. In many regions of the world where vitamin A deficiency is common, vitamin A supplementation has been shown to reduce the severity of some infections, such as ____
measles and diarrhea, in vitamin A-deficient children.
Many people in these areas also had small spots on their teeth (known as_____ excess fluoride. Although discolored, the mottled teeth were virtually free of ____
mottling - dental caries
______ are bone-building cells that produce collagen and add minerals to form healthy bone. Some of the fully mineralized osteoblasts mature to form ______, the most numerous cells in bones
osteoblasts - osteocytes
are biochemically active; they can take up calcium from the blood and release it back into the blood, as well as help bone become more dense, if needed
osteocytes
A failure to maintain adequate bone mass in the body 1st leads to a state of low bone mass called
osteopenia
