Physiological Functions and Deficiency Syndromes of Common Vitamins—cont’d

Vitamin	Chief Functions	Results of Deficiency	Characteristics	Good Sources
Riboflavin Vitamin B.	Important as coenzyme in cellular oxidation Essential to normal growth Participates in light adaptation Vital to protein metabolism Associated with niacin and vitamin B ₆ functions	Impaired growth Lassitude and weakness Cheilosis Glossitis Dermatitis Photophobia Cataracts	Water soluble Alcohol soluble Not destroyed by heat in cooking unless with alkali Unstable in light, especially in presence of alkali	Milk and milk products Enriched foods Whole grain breads and cereals Liver Meats Eggs
Niacin Nicotinic acid Nicotinamide Antipellagra	As the component of two important enzymes, it is important in glycolysis, tissue respiration, fat synthesis, and cellular energy produc- Nicotine acid, but not nicotinamide, causes vasodilation and flushing Prevents pellagra	Pellagra Gastrointestinal disturbances Mental disturbances Note: Associated with alcoholism	Soluble in hot water and alcohol	Milk Eggs Meats Legumes Enriched foods Whole grain cereals Note: Also formed in the body from dietary tryptophan (amino acid)
Vitamin B₆ Pyridoxine Pyridoxal Pyridoxamine	Used in hemoglobin synthesis Essential for metabolism of tryptophan to niacin Needed for utilization of certain other amino acids	Anemias Depressed immunity Dermatitis around eyes and mouth Neuritis Anorexia, nausea, and vomiting	Soluble in water and alcohol Rapidly inactivated in presence of heat, sunlight, or air	Meats Cereal grains Some fruits Nuts
Folate Folacin Folic acid	Essential for normal functioning of hematopoietic Important coenzyme for RNA and DNA synthesis Important in fetal development Functions interrelated with those of vitamin B₁₂	Anemia Note: Neural tube defects (e.g„ spina bifida) are associated with maternal deficiency; alcohol and contraceptives interfere with absorption	Slightly soluble in water Easily destroyed by heat in presence of acid Decreases when food is stored at room temperature Note: A large dose may prevent appearance of anemia in a case of pernicious anemia but still permit neurological symptoms to develop	Liver Green leafy vegetables Peas, beans Some fruits
Vitamin B ₁₂ Cyanocobalamin Hydroxycobalamin	Necessary for myelin synthesis Essential for normal development of red blood cells Associated with folate metabolism	Pernicious anemia Neurological disorders	Soluble in water or alcohol Unstable in hot alkaline or acid solutions	Found only in animal products (e.g., meats, eggs, dairy products) Most of vitamin B,. required by humans is synthesized by intestinal bacteria; can also be recycled