CHAPTER ONE
1.0 INTRODUCTION
Vitamins are groups of highly complex compounds, organic in nature, present in foodstuffs in traces, essential for normal metabolism and absence of these nutrients cause disorders whereas, resupply of these nutrients can cure the deficiency symptoms (Marshall, 2006). Vitamins are diverse in nature relative to fats, carbohydrates and proteins. Vitamins are differentiated from other groups by their organic nature and their classification depends on chemical nature and function. Very trace amounts of vitamins are needed for growth, development, health and reproduction. Some vitamins are deviants from usual definition and not always needed to be part of food stuff i.e. ascorbic acid, vitamin D and niacin. Ascorbic acid is synthesized by animals, niacin synthesized from tryptophan amino acid and vitamin D synthesized from UV radiation from sunlight. Therefore, specific species and under certain conditions vitamin D, ascorbic acid and niacin does not fit in the definition of vitamins (McDowell, 2000). So, far as classification of vitamins is concerned, these are divided into two main categories i.e. water soluble and fat soluble vitamins. Vitamins of B complex and C are water soluble whereas, vitamin A, D, E, and K are fat soluble. Fat soluble vitamins have association with fats and absorb with dietary fats. Absorption of fat soluble vitamins follow the same mechanics as for absorption of fats. Water soluble vitamins are not associated with fats and rendered unaffected by alterations in fat absorption (Wardlawet al., 2004).