Vitamins Flashcards Preview

► Food & Nutrition > Vitamins > Flashcards

Flashcards in Vitamins Deck (47)
Loading flashcards...
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.

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.

2

A vitamin that behaves more like a hormone than a vitamin is vitamin
a. A.
b. D.
c. E.
d. K.

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

3

The provitamin form of vitamin A that is found in plant pigments is
a. beta-carotene.
b. chlorophyll.
c. beta-xanthophyll.
d. calciferol.

beta-carotene.

4

Spinach, carrots, and sweet potatoes are good sources of
a. beta-carotene.
b. vitamin A.
c. vitamin D.
d. vitamin E.

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.

5

A rich source of vitamin A (retinol) is
a. liver.
b. bread.
c. broccoli.
d. apricots.

liver.

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

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.

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.

7

A deficiency of vitamin A may result in
a. osteoporosis.
b. bile obstruction.
c. breakdown of cell membranes.
d. night blindness.

night blindness.

8

An excellent natural food source of vitamin D is
a. fish liver oils.
b. wheat germ oil.
c. mineral oil.
d. margarine.

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.

9

The active hormonal form of vitamin D is
a. cholecalciferol.
b. calciferol.
c. calcitriol.
d. calcitonin.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

rickets.

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.

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.

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.

calcification of soft tissues.

such as kidneys and lungs as well as fragile bones.

17

A rich source of vitamin E is
a. sunflower oil.
b. spinach.
c. whole-wheat bread.
d. oatmeal.

sunflower oil.

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

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.

polyunsaturated fatty acids in the diet.

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

19

Vitamin E protects membranes because it acts as a(n)
a. barrier.
b. peroxide.
c. antioxidant.
d. clotting factor.

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.

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.

K.

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

21

A good food source of vitamin K is
a. spinach.
b. sunflower oil.
c. pork.
d. oranges.

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.

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.

retinol equivalents.

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

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.

parathyroid and calcitriol.

24

There is a metabolic partnership between vitamin E and
a. zinc.
b. chromium.
c. selenium.
d. iron.

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.

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.

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.

26

An alcoholic is most likely to be deficient in
a. biotin.
b. folic acid.
c. thiamin.
d. pyridoxine.

thiamin.

Alcohol-induced thiamin deficiency causes Wernicke's encephalopathy.

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

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.

28

The vitamin that is destroyed by light is
a. vitamin C.
b. niacin.
c. riboflavin.
d. biotin.

riboflavin.

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

29

The most important source of riboflavin is
a. milk.
b. lean meats.
c. enriched grains.
d. green leafy vegetables

milk.

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

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.

function as coenzymes.

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