6 Vitamins in milk and dairy products 6.1 Introduction Vitamins are organic chemicals required by the body in trace amounts but which cannot be synthesized by the body. The vitamins required for growth and maintenance of health differ between species; compounds regarded as vitamins for one species may be synthesized quate rates by other pecies. For example, only primates and the guinea pig require ascorbic acid (vitamin C; section 6.4) from their diet; other species possess the enzyme gluconolactone oxidase which is necessary for the synthesis of vitamin C from D-glucose or D-galactose. The chemical structures of the vitamins have no relationship with each other. The principal classification of vitamins is based on their solubility in water. Water-soluble vitamins are the b grour (thiamin, riboflavin, niacin, biotin, panthothenate, folate, pyridoxine(and elated substances, vitamin B6 )and cobalamin(and its derivatives, vitamin B12))and ascorbic acid(vitamin C)while the fat-soluble vitamins are retinol (vitamin A), calciferols(vitamin D), tocopherols(and related compounds vitamin E)and phylloquinone(and related compounds, vitamin K). The water-soluble vitamins and vitamin K function as co-enzymes while vitamin A is important in the vision process, vitamin D functions like a hormone and vitamin e is primarily an antioxidant Milk is the only source of nutrients for the neonatal mammal during rly stage of life viding macronut ents(protein, carbohydrate and lipid)and water, milk must also supply ufficient vitamins and minerals to support the growth of the neonate Human beings continue to consume milk into adulthood and thus milk and dairy products continue to be important sources of nutrients in the diet of many peoples worldwide. The concentrations of macronutrients and min erals in milk have been discussed in Chapters 1 and 5: vitamin levels in milk and dairy products will be considered here. Milk is normally processed a lesser or greater extent before consumption. Thus it is important to consider the influence of processing on the vitamin status of milk and dairy Recommended dietary allowances(RDA) for vitamins are recommended intake of various vitamin to ensure Ith of a high proportion of the human population. The rDa below refer to the United States population (Whitney and Rolfes, 1996). Reference nutrient intake6 Vitamins in milk and dairy products 6.1 Introduction Vitamins are organic chemicals required by the body in trace amounts but which cannot be synthesized by the body. The vitamins required for growth and maintenance of health differ between species; compounds regarded as vitamins for one species may be synthesized at adequate rates by other species. For example, only primates and the guinea-pig require ascorbic acid (vitamin C; section 6.4) from their diet; other species possess the enzyme gluconolactone oxidase which is necessary for the synthesis of vitamin C from D-glucose or D-galactose. The chemical structures of the vitamins have no relationship with each other. The principal classification of vitamins is based on their solubility in water. Water-soluble vitamins are the B group (thiamin, riboflavin, niacin, biotin, panthothenate, folate, pyridoxine (and related substances, vitamin B6) and cobalamin (and its derivatives, vitamin BIZ)) and ascorbic acid (vitamin C) while the fat-soluble vitamins are retinol (vitamin A), calciferols (vitamin D), tocopherols (and related compounds, vitamin E) and phylloquinone (and related compounds, vitamin K). The water-soluble vitamins and vitamin K function as co-enzymes while vitamin A is important in the vision process, vitamin D functions like a hormone and vitamin E is primarily an antioxidant. Milk is the only source of nutrients for the neonatal mammal during the early stage of life until weaning. Thus, in addition to providing macronutri￾ents (protein, carbohydrate and lipid) and water, milk must also supply sufficient vitamins and minerals to support the growth of the neonate. Human beings continue to consume milk into adulthood and thus milk and dairy products continue to be important sources of nutrients in the diet of many peoples worldwide. The concentrations of macronutrients and min￾erals in milk have been discussed in Chapters 1 and 5; vitamin levels in milk and dairy products will be considered here. Milk is normally processed to a lesser or greater extent before consumption. Thus it is important to consider the influence of processing on the vitamin status of milk and dairy products. Recommended dietary allowances (RDA) for vitamins are recommended intake of various vitamin to ensure the good health of a high proportion of the human population. The RDA values quoted below refer to the United States population (Whitney and Rolfes, 1996). Reference nutrient intake