Vitamins (Excluding C and E)

Vitamins are organic compounds distinct from amino acids, carbohydrates, and lipids. Vitamins are classified as either water soluble or fat soluble. Eight of the water soluble vitamins, known as the vitamin B complex, are required in relatively small amounts and have primarily coenzyme functions; these are thiamin, riboflavin, niacin, biotin, folic acid, pantothenic acid and vitamins B6 and B12. The water-soluble vitamins choline, myo-inositol, and vitamin C, are required in larger quantities and have functions other than coenzymes. Vitamins A, D, E, and K are the fat-soluble vitamins that function independently of enzymes or, in some cases such as vitamin K, may have coenzyme roles. The vitamin requirements of fish are affected by size, age, and growth rate, as well as by various environmental factors and nutrient interrelationships. This chapter reviews all 13 vitamins, their biochemistry and metabolic function, deficiency symptoms, requirements, and effects on immune responses and/or disease resistance.