chapter eight: the vitamins

Chapter Eight: The Vitamins Define vitamins and identify their

characteristics Differentiate between the two

classes of vitamins Name the fat-soluble vitamins

Major functions Deficiency results Significant food sources of each

Vitamins, cntd. Differentiate between active and

precursor forms of Vitamin A Describe the relationship between

Vitamin and Iron Absorption

Characteristics of Vitamins Occur in food in much smaller

amounts No energy contributions—no

kcalories Help and facilitate body processes Necessary for health but not

CURE--ALLS

Vitamins Defined Potent, essential, non-caloric,

organic nutrients Measured in milligrams or

micrograms Assist enzymes in the release of

energy from the energy nutrients Fat soluble and Water soluble forms Bioavailability—quantity provided

and amount absorbed

Fat-Soluble Vitamins Vitamins A, D, E, and K

Stored in Liver and Fatty Tissues Excess not excreted—can be toxic Travel in the blood with protein Not necessary to replenish daily

Vitamin A (Retinol and Beta-Carotene) Metabolic Functions--Antioxidant

Vitamin A, cntd. Vision—part of the pigment of the eye

that allows eye to adjust to changing light levels

Health of skin and linings of organs—health of epithelial cells that secrete mucus

Defense against infection Toxicity: animal sources and high

dosage supplements

Vitamin A, contd. Active vs. Precursor form

Active form (retinol) found in animal sources—fat of animals

Precursor form (beta-carotene) found in deep green and dark yellow fruits and vegetables—activate only when needed

Deficiency: Night Blindness and dryness of epithelial cells

Precursor Form of Vitamin A

Vitamin D (Calciferol) Not totally essential because the body can

make it from sunlight on the skin Functions: Makes calcium and phosphorus

available in blood to harden bones (bone-making and maintenance team)

Deficiencies: Rickets in children and Osteomalacia mostly in child-bearing women

Osteoporosis—impairs calcium absorption Sources: Eggs, liver, fish oils, and fortified

milk

Vitamin D Deficiency--Rickets

Vitamin E (Tocopherol) Function: Anti-oxidant—defends

against oxidation—especially polyunsaturated fatty acids

Heart health and protection against fibrocystic disease

Deficiency: Erythrocite hemolysis—breaking open of red blood cells

Toxicity: above 800 mg/RDA 8-10 mg

Vitamin E, contd. Sources:

Widespread in foods Vegetable oils, fruits, vegetables and

grains

Vitamin K Synthesis is possible in the intestinal

tract, but not sole source of it—not found in sterile GI tract (newborns)

Antibiotics can interfere with synthesis Function: necessary for normal blood

clotting Sources: green leafy vegetables,

cabbage family, liver, meats, milk, eggs, cereal and fruits

Water-Soluble Vitamins No accumulation in body tissues

from foods—large doses of supplements can be toxic

Easily absorbed and excreted in urine when there is excess

Need good sources daily

Vitamin B Complex Coenzymes involved in catabolic

and anabolic reactions in the body Thiamin(B1), Niacin(B3),

Riboflavin(B2), Pantothenic Acid & Biotin Involved in catabolic reactions Needed for the release of energy from

the energy nutrients

Riboflavin Source

Vitamin B Complex, contd. Vitamin B6

Anabolic reaction—synthesis of nonessential amino acids

Can minimize heart disease risk Folate

Anabolic reaction—new cell synthesis—especially of nervous system and spinal cord of developing fetus

Deficiency during pregnancy can lead to spina bifida—incomplete formation of spinal column

Spina Bifida

Vitamin B Complex, cntd. Vitamin B12 (Cyanocobalamin)

Anabolic reaction—formation of new cells, especially red blood cells

Deficiency is anemia

Vitamin B Complex, cntd. Deficiency diseases

Thiamin—Beriberi Niacin--Pellagra

Fortification and Enrichment of staple foods—especially cereals and grain products has reduced deficiencies of B Vitamins

Sources B Complex Vitamins

B Vitamin Complex, cntd. Good sources are widespread in

foods—whole foods best sources Light and heat sensitive—can be

lost in cooking liquid Folate: Best sources are liver,

legumes, and green leafy vegetables (foliage)

Vitamin B12: Only available in animal products

Vitamin C (Ascorbic Acid) Function: Necessary for the formation

of the protein collagen—protein of connective tissue (wound healing); also an antioxidant for water solubles

Deficiency: Scurvy—bleeding gums, pinpoint hemorrhages, bruising easily, failure of wounds to heal

RDA: 75 -100 mg Increases during pregnancy and lactation

Vitamin C, cntd. Stress, infections and smoking

increase needs up to 100 mg Oral contraceptives increase needs

Sources: Fruits and Vegetable groups only—especially citrus fruits, strawberries, and cruciferous vegetables

Sources of Vitamin C

Cruciferous Vegetables

Vitamin Supplements—Are They Necessary? Good diet including a variety of

foods should supply vitamins & minerals needed

Those who may need them Low kcalorie dieters Depressed appetite—illness, age Illnesses that impair absorption Heavy blood losses—menstruation

(Iron)

Vitamin Supplements, cntd.

During pregnancy and lactation—especially iron and folate

Strict (vegan) vegetarians Newborn infants Recovery from infection or surgery Breast fed infants

Best if prescribed by R.D. or M.D.—multivitamin usually safe

Phytochemicals Found in foods—impart tastes, aromas,

colors, etc. Act as antioxidants and suppress

diseases Diets rich in whole grains, legumes,

vegetables and fruits can be protective against heart disease and cancer

Eat colorful foods—orange, red and green

Test Questions The psychological desire to eat is

referred to as: Satiety Appetite Hunger Obesity

Obese people have much more lipoprotein lipase activity than lean people True False

Which of the following is NOT a fat-soluble vitamin? A E K C D

Which vitamin is present only in foods of animal origin? Riboflavin Vitamin B12 Pantothenic acid The inactive form of Vitamin A