Chapter 7: Vitamins

Question 1

For a compound to be classified as a vitamin, it must

a. be synthesized by the body.
b. be required in large quantities.
c. perform a vital function.
d. be water soluble.

Answer 1

perform a vital function.
ANS: C
t must be a vital, organic, dietary substance that is not a carbohydrate, fat, protein, or mineral and is necessary in only very small amounts to perform a specific metabolic function or prevent an associated deficiency. It also cannot be manufactured by the body in sufficient amounts to sustain life and must be supplemented by the body.

Question 2

A vitamin that behaves more like a hormone than a vitamin is vitamin

a. A.
b. D.
c. E.
d. K.

Answer 2

Vitamin D is a prohormone made in the skin by sunlight.

Question 3

The provitamin form of vitamin A that is found in plant pigments is

a. beta-carotene.
b. chlorophyll.
c. beta-xanthophyll.
d. calciferol.

Answer 3

beta-carotene.

Question 4

Spinach, carrots, and sweet potatoes are good sources of

a. beta-carotene.
b. vitamin A.
c. vitamin D.
d. vitamin E.

Answer 4

beta-carotene.

Carotene is a group name of three red and yellow pigments (alpha-, beta-, and gamma-carotene) found in dark green and yellow vegetables and some fruits. The body converts beta-carotene to vitamin A.

Question 5

A rich source of vitamin A (retinol) is

a. liver.
b. bread.
c. broccoli.
d. apricots.

Answer 5

liver.

Liver is a rich source of preformed, natural vitamin A. Other sources include fish liver oils, egg yolk, butter, and cream.

Question 6

An important function of vitamin A is to

a. be incorporated into the bile.
b. help with blood clotting.
c. act as an antioxidant.
d. help form the visual pigment rhodopsin in the eye.

Answer 6

help form the visual pigment rhodopsin in the eye.

Vitamin A helps form the visual pigment rhodopsin in the eye. Retinol, the name given to vitamin A, is an essential part of rhodopsin, commonly known as visual purple. This light-sensitive substance enables the eye to adjust to the different amounts of available light.

Question 7

A deficiency of vitamin A may result in

a. osteoporosis.
b. bile obstruction.
c. breakdown of cell membranes.
d. night blindness.

Answer 7

night blindness.

Question 8

An excellent natural food source of vitamin D is

a. fish liver oils.
b. wheat germ oil.
c. mineral oil.
d. margarine.

Answer 8

fish liver oils.

All other foods have been fortified with vitamin D. Because milk is a common food and already contains calcium and phosphorus, it is the most practical to fortify with this vitamin.

Question 9

The active hormonal form of vitamin D is

a. cholecalciferol.
b. calciferol.
c. calcitriol.
d. calcitonin.

Answer 9

calcitriol.

Vitamin D is made in the body with the help of the sun’s ultraviolet rays. The compound made in the skin by sunlight is a prohormone. This irradiated compound, cholecalciferol (calciferol), is in its inactive form. It is then activated by two successive enzymes, first in the liver and then in the kidney, to become the active form, calcitriol.

Question 10

Two foods that are commonly fortified with vitamin D are

a. cereals and macaroni products.
b. milk and margarine.
c. flour and salt.
d. vegetable oils and shortenings.

Answer 10

milk and margarine.

Because milk is a common food and already contains calcium and phosphorus, it is the most practical to fortify with this vitamin. Butter substitutes, such as margarines, are also fortified.

Question 11

Synthesis of the active hormonal form of vitamin D is the result of the combined action of the

a. skin, liver, and kidney.
b. pancreas, thyroid, and liver.
c. skin, skeleton, and liver.
d. kidney, skeleton, and liver.

Answer 11

skin, liver, and kidney.

Vitamin D is made in the body with the help of the sun’s ultraviolet rays. The compound made in the skin by sunlight is a prohormone. This irradiated compound, cholecalciferol (calciferol), is in its inactive form. It is then activated by two successive enzymes, first in the liver and then in the kidney, to become the active form, calcitriol.

Question 12

The last organ involved in the production of the physiologically active form of vitamin D is the

a. liver.
b. kidney.
c. intestine.
d. skin.

Answer 12

kidney.

Cholecalciferol (inactive form found in skin) is activated by two successive enzymes, first in the liver and then in the kidney, to become the active form, calcitriol.

Question 13

The primary function of vitamin D is to regulate the absorption and metabolism of the minerals

a. sodium and potassium.
b. iron and phosphorus.
c. calcium and phosphorus.
d. sodium and calcium.

Answer 13

calcium and phosphorus.

The hormone form calcitriol acts with two other hormones: parathyroid hormone and the thyroid hormone calcitonin. In balance with these two hormones, vitamin D hormone stimulates the absorption of calcium and phosphorus in the small intestine.

Question 14

A vitamin D deficiency in growing children that results in the malformation of skeletal tissue, especially the long bones, is referred to as

a. rickets.
b. scurvy.
c. pellagra.
d. beriberi.

Answer 14

rickets.

Question 15

Recommended intakes for vitamin D are difficult to establish because

a. exposure to sunlight varies.
b. it is present in so many foods.
c. the body stores such large amounts.
d. the amount in food varies with the season.

Answer 15

exposure to sunlight varies.

because of its unique hormonelike nature, difference in exposure to sun (exposure varies from person to person depending on ability to go outside and the climate), and limited food sources.

Question 16

A toxic level of vitamin D is most likely to result in

a. liver damage.
b. hyperpigmentation.
c. blindness.
d. calcification of soft tissues.

Answer 16

calcification of soft tissues.

such as kidneys and lungs as well as fragile bones.

Question 17

A rich source of vitamin E is

a. sunflower oil.
b. spinach.
c. whole-wheat bread.
d. oatmeal.

Answer 17

sunflower oil.

The richest sources of vitamin E are vegetable oils. Other food sources include nuts, fortified cereals, and avocado.

Question 18

The requirement for vitamin E varies by the amount of an individual’s

a. sun exposure.
b. selenium in the diet.
c. animal fats in the diet.
d. polyunsaturated fatty acids in the diet.

Answer 18

polyunsaturated fatty acids in the diet.

The Dietary Reference Intake for men and women aged 14 years and older is 15 mg/day.

Question 19

Vitamin E protects membranes because it acts as a(n)

a. barrier.
b. peroxide.
c. antioxidant.
d. clotting factor.

Answer 19

antioxidant.

Vitamin E protects membranes by acting as nature’s most potent fat-soluble antioxidant. The polyunsaturated fatty acids in lipid membranes are easy for oxygen to break down, and vitamin E can interrupt this oxidation and protect the fatty acids of the cell membrane from damage.

Question 20

The fat-soluble vitamin responsible for the synthesis of blood-clotting factors by the liver is vitamin

a. A.
b. D.
c. E.
d. K.

Answer 20

K.

The basic function of vitamin K is in the blood-clotting process. The most known vitamin K–dependent blood factor is prothrombin.

Question 21

A good food source of vitamin K is

a. spinach.
b. sunflower oil.
c. pork.
d. oranges.

Answer 21

spinach.

Vitamin K is found in green leafy vegetables, which provide 50 to 800 mcg of phylloquinone per 100 g of food. Smaller amounts are found in milk and other dairy, meats, fortified cereals, fruits, and vegetables.

Question 22

In the past, vitamin A content was listed in International Units (IU); it is now listed in

a. milligrams.
b. micrograms.
c. beta-carotene equivalents.
d. retinol equivalents.

Answer 22

retinol equivalents.

Vitamin A is listed in retinol equivalents. One IU of vitamin A equals 0.3 mcg retinol or 0.6 mcg beta-

Question 23

The hormones that participate in calcium metabolism are

a. estrogen and oxytocin.
b. cortisone and epinephrine.
c. aldosterone and thyroxine.
d. parathyroid and calcitriol.

Answer 23

parathyroid and calcitriol.

Question 24

There is a metabolic partnership between vitamin E and

a. zinc.
b. chromium.
c. selenium.
d. iron.

Answer 24

selenium.

is a trace mineral that works with vitamin E as an antioxidant. A selenium-containing enzyme, glutathione peroxidase, is the second line of defense in preventing oxidative damage to cell membranes. Selenium spares vitamin E by reducing its requirement, the same as vitamin E does for selenium.

Question 25

An athlete who increases his or her intake of pasta will also increase his or her need for

a. folic acid.
b. thiamin.
c. pyridoxine.
d. vitamin C.

Answer 25

thiamin.

Thiamin acts a coenzyme factor related to the production of energy from glucose and the storage of energy as fat, making energy available to support normal growth.

Question 26

An alcoholic is most likely to be deficient in

a. biotin.
b. folic acid.
c. thiamin.
d. pyridoxine.

Answer 26

thiamin.

Alcohol-induced thiamin deficiency causes Wernicke’s encephalopathy.

Question 27

The three body systems that can be affected by a thiamin deficiency are the _____ systems.

a. nervous, respiratory, and urinary
b. nervous, cardiovascular, and gastrointestinal
c. gastrointestinal, respiratory, and endocrine
d. lymphatic, cardiovascular, and endocrine

Answer 27

nervous, cardiovascular, and gastrointestinal

can all be affected by thiamin deficiency. The central nervous system depends on glucose for energy; if thiamin is not present in adequate amounts, sufficient energy cannot be made for the nerves to perform their functions. The heart muscle depends on thiamin as well. Without adequate thiamin, the heart muscle weakens and heart failure results. Thiamin also is necessary for the gastrointestinal tract to function properly. The cells of smooth muscle and secretory glands must have energy to perform their work, and thiamin is a necessary agent for producing that energy.

Question 28

The vitamin that is destroyed by light is

a. vitamin C.
b. niacin.
c. riboflavin.
d. biotin.

Answer 28

riboflavin.

is easily destroyed by light. Milk, a major source of riboflavin, is sold and stored in plastic or cardboard containers.

Question 29

The most important source of riboflavin is

a. milk.
b. lean meats.
c. enriched grains.
d. green leafy vegetables

Answer 29

milk.

is the major source of riboflavin. Each serving of milk and milk products contains between 0.3 and 0.5 mg of riboflavin.

Question 30

The function of all B-complex vitamins is to

a. regulate fluid balance.
b. function as body structures.
c. function as coenzymes.
d. provide calories for energy.

Answer 30

function as coenzymes.

that are necessary agents to break down compounds, yet they are not consumed in the process.

Question 31

The disease associated with niacin deficiency is

a. anemia.
b. cheilosis.
c. pellagra.
d. beriberi.

Answer 31

pellagra.

is a disease caused by the lack of niacin. It is characterized by skin lesions along with gastrointestinal, mucosal, neurologic, and mental symptoms. The four Ds associated with pellagra are dermatitis, diarrhea, dementia, and death.

Question 32

The amino acid that can be converted to niacin in the body is

a. leucine.
b. phenylalanine.
c. tryptophan.
d. valine.

Answer 32

tryptophan.

Some of the niacin the body requires can be made from the essential amino acid tryptophan. The total requirement in the body for niacin is stated in terms of niacin equivalents to account for both sources.

Question 33

A good food source of niacin is

a. a banana.
b. a tomato.
c. beef.
d. oatmeal.

Answer 33

beef.

Meat is a major source of niacin. The greatest intake of niacin in the United States comes from mixed dishes high in meat, poultry, or fish.

Question 34

The vitamin most closely associated with protein metabolism is

a. thiamin.
b. pyridoxine.
c. folic acid.
d. choline.

Answer 34

pyridoxine.

Vitamin B6 (pyridoxine) has an essential role in protein metabolism and function in many cell reactions involving amino acids.

Question 35

Which of the following diets can help ensure adequate and balanced vitamin intake?

a. A high-calorie diet composed of mainly fruits and vegetables
b. A high-protein diet concentrating on red meat and fish
c. A varied diet composed of all food groups eaten in controlled portions
d. A varied diet with a higher emphasis on grains and fish supplemented with a commercially prepared vitamin

Answer 35

A varied diet composed of all food groups eaten in controlled portions

Question 36

The need for pyridoxine varies with the dietary intake of

a. carbohydrates.
b. fats.
c. protein.
d. minerals.

Answer 36

protein.

The need for pyridoxine varies with the dietary intake of protein. Vitamin B6 (pyridoxine) has an essential role in protein metabolism and function in many cell reactions involving amino acids

Question 37

The person most at risk for vitamin D deficiency is a

a. 12-year-old girl who plays soccer at the local playground twice a week.
b. 28-year-old mother who breastfeeds her 5-month-old infant and takes a daily stroll in the neighborhood.
c. 62-year-old woman who lives in a cold climate and rarely goes outdoors.
d. 42-year-old man who plays golf once a week.

Answer 37

62-year-old woman who lives in a cold climate and rarely goes outdoors.

Vitamin D is synthesized in the skin with exposure to sunlight. People who do not go outdoors may be at higher risk for developing a vitamin D deficiency.

Question 38

The best food source of folic acid is

a. grapefruit.
b. chicken.
c. cheese.
d. broccoli.

Answer 38

broccoli.

Rich sources of folate are found in chicken and beef liver, green leafy vegetables, yeast, and legumes. Broccoli would be a high source of folate among the choices.

Question 39

A folic acid deficiency induces a form of anemia called _____ anemia.

a. microcytic
b. megaloblastic
c. pernicious
d. aplastic

Answer 39

megaloblastic

Megaloblastic anemia can be caused by a lack of folate. It is a particular risk during pregnancy because of the increased fetal growth demands. Growing teenagers who do not eat healthily and those who smoke also may be at risk for this type of anemia.

Question 40

The B vitamin predominantly found in foods of animal origin is

a. pantothenic acid.
b. niacin.
c. thiamin.
d. cobalamin.

Answer 40

cobalamin.

Because cobalamin occurs as a protein complex in foods, its sources are mostly of animal origin.

Question 41

Vitamin C deficiency is associated with

a. scurvy.
b. beriberi.
c. pernicious anemia.
d. megaloblastic anemia.

Answer 41

scurvy.

. It is a hemorrhagic disease with diffuse tissue bleeding, painful limbs and joints, thickened bones, and skin discoloration from tissue bleeding. Bones fracture easily, wounds do not heal properly, gums are swollen and bleed, and teeth loosen.

Question 42

A 62-year-old woman who smokes 1 pack of cigarettes a day and whose food intake records reveal a minimal intake of vitamin C foods may be at risk for

a. easy bruising and pinpoint hemorrhages.
b. cracked and bleeding lips.
c. fevers and infections.
d. neurologic disorders.

Answer 42

easy bruising and pinpoint hemorrhages.

Signs of vitamin C deficiency are tissue bleeding, including easy bruising and pinpoint skin hemorrhages. Smokers deplete their supply of vitamin C more rapidly than nonsmokers. Cigarette smoke is a source of environmental free radicals, and vitamin C is needed to break down toxic compounds in cigarette smoke.

Question 43

An example of a meal high in vitamin C is

a. bacon, lettuce, and tomato sandwich and strawberries.
b. hamburger, French fries, and salad.
c. pasta salad, whole-grain roll, and apple.
d. nachos with refried beans and salsa.

Answer 43

bacon, lettuce, and tomato sandwich and strawberries.

The best sources of vitamin C are citrus fruits, tomatoes, cabbage and other leafy green vegetables, berries, melons, peppers, broccoli, potatoes, and yellow vegetables.

Question 44

Phytochemicals act as

a. vitamins and minerals.
b. cofactors and enzymes.
c. antioxidants and hormones.
d. antibiotics and antifungals.

Answer 44

antioxidants and hormones.

The beneficial effects of phytochemicals are believed to result from synergistic actions of multiple nutrients as opposed to acting as an isolated compound.

Question 45

Foods rich in phytochemicals include

a. mushrooms and algae.
b. fruits and vegetables.
c. yogurt and goat’s milk.
d. soy milk and tofu.

Answer 45

fruits and vegetables.

The term phytochemical comes from the Greek word phyton, meaning plant.

Question 46

A young woman who is interesting in becoming pregnant should be counseled on healthy eating choices, especially regarding folate-containing foods, which may help prevent

a. neural tube defects.
b. osteomalacia.
c. pernicious anemia.
d. aplastic anemia.

Answer 46

neural tube defects.

Neural tube defects, including spina bifida and anencephaly, are the most common birth defects involving the brain and spinal cord. Additional folic acid intake can significantly improve the folate status of women.

Question 47

A food or food ingredient that may provide a health benefit beyond its basic nutritional value is called a(n)

a. phytochemical.
b. functional food.
c. vitamin.
d. essential fatty acid.

Answer 47

functional food.

include any food or food ingredient that may provide a health benefit beyond its basic nutritional value. Such foods are also called nutraceuticals or designer foods.