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127 terms

nutrition ch 10

ch 10 question
STUDY
PLAY
what is a feature of vitamins?
the quantities present in foods are measured in micrograms or milligrams
what is a precursor?
a substance that is used to synthesize another compound
what is meant by the bioavailability of a vitamin in food?
the amount absorbed and subsequently used by the body
general characteristics of the water-soluble vitamins include what?
toxic levels in the body are rarely found
they are absorbed directly into the blood
excesses are eliminated from the kidneys
what are general characteristics of the fat-soluble vitamins
-absorption is via the lymphatic circulation
-several of them require protein carriers for transport
-they can be stored in relatively large amounts in certain body tissues
cooking a food in liberal amounts of water is least likely to affect the vitamin content of?
vitamin A
which of the following vitamins would be removed in the production of skim milk
vitamin A
what is the primary excretory route for the water-soluble vitamins
kidney
when thiamin is consumed in excess of needs, how does the body treat the excess?
excreted primarily in the urine
what is a chief function of the b vitamins
coenzyme participation
which of the following explains why b vitamin deficiencies lead to lack of energy
coenzymes needed for energy metabolism are produced in insufficient amounts
which of the following describes the basic function of a coenzyme
attaches to an enzyme and allows a chemical reaction to occur
which function has a requirement for thiamin
energy release from energy-yielding nutrients
what is the primary chemical reaction in which thiamin participates as a coenzyme
assists in removal of one-carbon units from compounds involved in energy metabolism
what is a coenzyme form of thiamin
thiamin pyrophosphate
beriberi results from a deficiency of what
thiamin
(high intake of white rice)
what is a characteristic of thiamin nutrition
it is an integral part of the nerve cell membrane
approx. what % of alcoholics exhibit thiamin deficiency
80
which of the following provides the most thiamin per serving size
ham, soy milk
-poor sources include seafood and cheeses
how does the method of cooking affect thiamin stability
microwaving the food conserves much of the thiamin
riboflavin in its coenzyme form functions in the transfer of
hydrogen atoms
which of the following vitamins is involved substantially in energy transformation reactions
riboflavin
what is indicative of a dietary deficiency of riboflavin
inflamed mouth membranes
what food group contains high amounts of riboflavin when expressed per kcal
vegetables
what is ariboflavonosis
the vitamin B2 deficiency disease
-bad when diet is low in dairy foods
riboflavin is most easily destroyed when exposed to
UV light
the coenzyme FAD is formed from what vitamin
riboflavin
which of the following is a property riboflavin in nutrition
stability to heat is good
what is property of niacin in nutrition
it can be synthesized in the body from the essential amino acid tryptophan
what property is shared by niacin and riboflavin coenzymes
acceptance and transfer of hydrogen atoms
when the diet contains an adequate amount of protein, what amino acid can be used by the body to synthesize niacin
tryptophan
the vitamin deficiency disease pellagra means
"tough skin"
low-protein diet with corn as principal food causes a deficiency of what vitamin
niacin
-the disease pellagra also appears
symptoms include diarrhea, dementia, dermatitis
a general niacin deficiency is know to be manifested in abnormalities of all of the following organs...
skin
nervous system
gastrointestinal tract
which substance is found in corn that contributes to the development of pellagra
leucine
which of the following overt side effects is likely to appear after a person ingests a high quantity of nicotinic acid?
painful, tingling, itching sensation
niacin flush
result in dilation of capillaries, increased HDL, lowering LDL
your friend Jane just returned from the doctor who diagnosed her with a specific vitamin B toxicity. what is the only possible vitamin with toxicity symptoms
niacin
what is approx. niacin RDA for adults
15 niacin equivalents
-chicken is the best source
features of biotin in nutrition include all of the following
it functions in the breakdown of amino acids and fatty acids
it functions as a carrier of CO2 in energy metabolism
a deficiency can be induced by ingesting large quantities of raw egg whites
among the following compounds that serve as coenzymes in metabolism, which is considered a vitamin for human beings?
biotin
which of the following is synthesized by intestinal bacteria
biotin
what is the adult adequate intake for biotin
30 µg
what vitamin forms a part of coenzyme A and is known to sustain substantial losses during processing of fodd
pantothenic acid
forms of vitamins B6 include
pyridoxal
pyridoxine
pyridoxamine
which vitamin is stored primarily in muscle tissue and involved intensively in amino acid metabolism
vitamin b6
the chief symptoms of early vitamin b6 deficiency include
confusion and depression
all of the following are features of vitamin b6 metabolism
a deficiency leads to depression
its destruction and excretion are promoted by alcohol intake
it functions primarily as the coenzyme pyridoxal phosphate
what is the tolerable upper intake level for vitamin b6
and adult RDA
100 mg
1.3 mg
which of the following statements reflects our knowledge of water-soluble vitamin toxicity
toxicity symptoms for vitamin B6 can be severe and irreversible
in what major way does alcohol intake affect vitamin b6 metabolism
it dislodges the PLP coenzyme from its enzyme
what food is richest in vitamin b6 on a per-kcal intake basis
veggies
what is an essential nutrient for human beings
folate
pteroylglutamic acid is known as
folate
all of the following are properties of folate in nutrition
it is needed for proper functioning of vitamin b12
it requires enzymes on the intestinal mucosa to enhance its absorption from most foods
what characteristic is shared by vitamin b 12 and folate
both are required for nucleic acid synthesis
a person with a disorder that limits absorption of bile is at increased risk for deficiency of
folate
what is most likely the explanation for the impaired functioning of the GU tract resulting from folate deficiency
since folate functions, in large part, in the process of cell renewal, a deficiency slows mucosal cell replacement, thereby resulting in decreased GI functioning
approx. what % of dietary folate is bioavailable
-what % bioavailability of a folate supplement taken on an empty stomach is
50
100
research has shown that the risk for neural tube defects is lowered by taking supplements of
folate
what is a type of neural tube defect
spina bifida
a deficiency of what vitamin results in accumulation of homocysteine in the blood
folate
what substance is known to adversely affect folate utilization
regular use of antacids
what is representative of folate availability in foods
much of the vitamin is lost due to heat and oxidation
what is required for the absorption of dietary vitamin b12
intrinsic factor which attaches itself to the vitamin allowing absorption into the intestine
-pepsin
-hydrochloric acid
pernicious anemia results from a deficiency of
vitamin b12
the absorption of which of the following vitamins is most affected by the disorder atrophic gastritis
vitamin b12
if a person refrained from ingesting any of the water-soluble vitamins, deficiency symptoms would appear last for
vitamin b12
3 yrs
which of the following is a feature of vitamin b12 bioavailability
synthetic b12 in supplements form is highly utilizable
what is a characteristic of vitamin b12
it is inactivated when the food is heated in a microwave
the adult RDA for vitamin b12 is
2.4
which of the following vitamins has an RDA
cobalamin
which of the following is known to perform an essential function in the human body
carnitine
what is not known to be required in the diet of humans
lipoic acid
what is frequently affected by deficiencies of the b vitamins
tongue (smooth tongue)
what characteristic is shared by vitamins b6 b12 c and folate
consumption prevents anemia
function of vitamin c
antioxidant agent
cofactor in collagen formation
the protein that requires ascorbic acid for its formation is
collagen
why might vitamin c supplements be beneficial in treating the common cold
they deactivate histamine
which of the following is an early sign of vitamin c deficiency
bleeding gums
in the us what is the RDA for adults for vitamin c
how much more vitamin c
75-90 mg
what term is used to describe the outcome of a diagnostic test that apparently shows that you have mononucleosis when in reality you do not
false positive
a vitamin supplement labeled as "high potency" contains an amount that is
100% or more of the daily value
what are the features of the fat-soluble vitamins
requires bile for absorption
found in the fat and oily parts of foods
pose a greater risk for developing a toxicity than water-soluble vitamins
what is the major carrier of the fat soluble vitamins from the intestinal epithelial cell to the circulation
chylomicrons
what is a property of the fat-soluble vitamins
deficiency symptoms may take years to develop on a poor diet
if the diet contain precursor vitamin a which of the following tissues can use it to form vitamin a
intestinal cells
what food substance can be converted to vitamin a in the body
beta-carotene
how many different forms of vitamin a are active in the body
3
all of the following are forms of vitamin a
retinol
retinal
retinoic acid
which of the following is responsible for transporting vitamin a from the liver to other tissues
retinol-binding proteins
vitamin a does not play an important role in what process
blood clotting
what describes an association of vitamin a and vision
light causes retinal to shift from a cis to a trans configuration
approx what % of the body's vitamin a stores are found in the liver
90
which of the following describes the primary function of vitamin a in bone health
it assist enzymes that degrade certain regions of the bone therapy allowing remodeling to occur
why does vitamin a status depend on the person's protein status
transport of the vitamin within the body requires sufficient protein to synthesize retinol-binding protein
the first detectable sign of vitamin a deficiency is usually
night blindness
-xerosis
-most severe in newborns
what occurs from a prolonged dietary deficiency of vitamin a
xerophthalmia
-keratinization: cornea is most affected
the preferred unit of expression of vitamin a is the
retinol activity equivalent
how many micrograms of dietary beta carotene are equivalent to 1 retinol activity equivalent
12
the rda for vitamin A is approx
800 retinol activity equivalents
pregnant women limit vit a to less than 4 times the RDA
what is a feature of carotenoids in food
absorption from the GI tract is blunted by consuming a salad with fat-free dressing
what provides the least amount of precursor vitamin a
corn
the plant version of vitamin d is known as
animal version?
ergocalciferol
cholecalciferol
all of the following are required for the complete synthesis of activated vitamin d
skin
liver
kidney
which of the following compounds serves as the major precursor the body's synthesis of vitamin d
cholesterol
in what tissues must a molecule of vitamin d be chemically altered to yield a compound that is fully active
liver and kidney
the major target organs for the action of activated vitamin d include
bone
kidney
intestine
what is the main function of vitamin d
promotes calcium and phosphorus absorption and promotes calcium mobilization from bone
name of the vitamin d disease in adults
osteomalacia
adult women
what is not known to promote vitamin d deficiency in the elderly
excessive use of hypertension medications
what is a characteristic of vitamin d nutrition
prolonged exposure to sunlight degrades the vitamin d precursor in skin, thus preventing vitamin d toxicity
what vitamin prevents the oxidation of low-density lipoproteins
e- acts as a antioxidant
what is the role of vitamin e in the metabolism of free radicals
eliminator
the major function of vitamin e is to inhibit the destruction of
polyunsaturated fatty acids
what disorder may result from vitamin e deficiency in people
erythrocyte hemolysis
which of the following is a property of the tocopherols
easily destroyed by air and oxygen
what is a major source of vitamin e in the diet
vegetable oils
what properties do vitamin d and k share
both are synthesized by the body
what is prothrombin
a protein needed for blood clot formation
in what chief capacity does vitamin k function
blood clotting
it participates in synthesis of bone proteins
what is a feature of osteocalcin
it requires vitamin k to blind to bone-forming minerals
all of the following are features of vitamin k in nutrition
infants frequently require a supplement at birth
-good food sources are plants of the cabbage family
-risk of deficiency is increased in people taking antibiotics for prolonged periods
what organ would you expect to find vitamin k in in large quantities
liver
what is a feature of vitamin k
no adverse effects have been reported with high intakes
what type of foods should be controlled in individuals taking anticoagulant medicines
green leafy vegetables
approx what % of the body's store of vitamin k is derived from GI tract bacterial synthesis
50
which is NOT a fat-soluble vitamin
cyanocobalamin