Physiological Functions and Deficiency Syndromes of Common Vitamins—cont’d
Vitamin	Chief Functions	Results of Deficiency	Characteristics	Good Sources
Vitamin E Alpha-tocopherol Beta-tocopherol Gamma-tocopherol	Important antioxidant that: Prevents red blood cell hemolysis Protects vitamin A and unsaturated fatty acids from oxidation Promotes cell membrane integrity Improves immune response May protect against cancer	Red blood cell resistance to rupture is decreased, but deficiency seldom occurs except in premature infants and people with chronic fat malabsorption	Soluble in fat Stable to heat in absence of oxygen and ultraviolet light Unstable under freezing and processing	Vegetable oils Margarine Whole grain or fortified cereals Wheat germ Green leafy vegetables
Vitamin K Menadione Phylloquinone Menaquinone	Promotes synthesis of clotting factors	Prolonged clotting time, resulting in bleeding Note: Seldom occurs in the absence of anticoagulant drugs; in addition to food sources, intestinal bacteria manufacture approximately half the body's requirement Fat malabsorption can cause deficiency Synthetic form (menadione) does not depend on fat absorption	Soluble in fat Stable to heat	Green leafy vegetables Dairy products Intestinal bacteria
Vitamin C Ascorbic acid	Essential to formation of intracellular cement substances in a variety of tissues including skin, dentin, cartilage, and bone Important in healing of wounds and bone fractures Prevents scurvy Facilitates absorption of Protects folate Antioxidant Promotes capillary permeability	Mild: Lowered resistance to infec- Joint tenderness Susceptibility to dental caries, pyorrhea, and bleeding gums Delayed wound healing Bruising Hemorrhage Anemia Scurvy Note: Many drugs affect availability	Soluble in water Easily destroyed by oxidation; heat hastens the process Lost in cooking, particularly if water in which food was cooked is discarded; loss is greater if cooked in iron or copper Quick-frozen foods lose little of their vitamin C Stored in the body to a limited extent	Abundant in most fresh fruits and vegetables, especially citrus fruit and juices, tomato and orange Artificial: Ascorbic acid Cevitamic acid
Thiamine Vitamin B,	Important role in carbohydrate metabo- Essential for maintenance of normal appetite Essential for normal functioning of nervous tissue Coenzyme for cellular energy production	Mild: Loss of appetite Impaired metabolism of starches and sugars Emaciation Irritability Severe: Various nervous disorders Loss of coordinating power of muscles Beriberi Paralysis in humans	Soluble in water Not readily destroyed by ordinary cooking temperatures Destroyed by exposure to heat, alkali, or sulfites Not stored in body Note: Deficiency is often associated with alcoholism	Widely distributed in plant and animal tissues but seldom occurs in high concentration, except in brewer's yeast Enriched or whole grain cereals Pork Peas, beans Nuts Artificial: Concentrates from yeast Rice polishings Wheat germ