Chemistry Reference
In-Depth Information
12
Fat-Soluble Vitamins and Vitamin C
in Milk and Milk Products
P.A. Morrissey and T.R. Hill
12.1.
Introduction
Vitamins are a heterogeneous group of organic substances that are present in
our natural foods, that are of very high biological potency and that are
required in extremely small concentrations for growth and maintenance of
normal cells and body function. They need to be supplied in the diet, because
the body either cannot make them or cannot do so in amounts that are
essential for growth, maintenance and normal and body function. Vitamin
families are chemically heterogeneous and are generally classified according
to their physical properties, i.e. as being either fat soluble, or water soluble.
The fat-soluble vitamins tend to have predominately aromatic or aliphatic
character, whereas the water-soluble vitamins tend to have one or more polar
or ionizable groups (carboxyl, keto, hydroxyl, amino or phosphate).
The first half of the twentieth century saw the identification, extraction
and purification of many vitamins. The synthesis and production of these
essential nutrients soon followed and cures for many classical nutritional
diseases, including scurvy, beriberi, pellagra and rickets, were demonstrated.
More recently, several epidemiological studies have examined the association
between vitamin intake/status and various chronic diseases, such as cancer,
cardiovascular diseases and osteoporosis. Recognition of the prominent role
of some micronutrients as antioxidants in preventing free radical-mediated
tissue damage has awakened a re-evaluation of vitamin status and has shed
new light on the importance of some vitamins in the prevention of some
