VITAMINS IN MILK AND DAIRY PRODUCTS^2736.11
6.12
R,I I Tocotrienols
R3Vitamin E is a very effective antioxidant. It can easily donate a hydrogen
from the phenolic -OH group on the chromanol ring to free radicals. The
resulting vitamin E radical is quite unreactive as it is stabilized by delocal-
ization of its unpaired electron into the aromatic ring. Vitamin E thus
protects the lipids (particularly polyunsaturated fatty acids) and membranes
in the body against damage caused by free radicals. The role of vitamin E
is of particular importance in the lungs where exposure of cells to oxygen is
greatest. Vitamin E also exerts a protective effect on red and white blood
cells. It has been suggested that the body has a system to regenerate active
vitamin E (perhaps involving vitamin C) once it has acted as an antioxidant.
Vitamin E deficiency is normally associated with diseases of fat mal-
absorption and is rare in humans. Deficiency is characterized by erythrocyte
haemolysis and prolonged deficiency can cause neuromuscular dysfunction.
Hypervitaminosis E is not common, despite an increased intake of vitamin
E supplements. Extremely high doses of the vitamin may interfere with the
blood clotting process.
The RDAs for vitamin E are 10 mg and 8 mg c(-TE day- for men and
women, respectively. UK RNI values have not been established for vitamin
E since its requirement is largely dependent on the content of polyunsatu-
rated lipids in the diet. However, the Department of Health (1991) suggested
that 4 and 3 mg a-TE day- are adequate for men and women, respectively.
The major food sources of vitamin E are polyunsaturated vegetable oils and
products derived therefrom (e.g. maragrine, salad dressings), green and leafy