Nutrients ingested are biologically available
(Gibson 1994) This is due to a number of reasons related to the physical nature
and chemical composition of foods and to the individual's digestive capacity. One of the most important
factors seems to be the presence of dietary components that interferes with digestion and
inhibits absorption of some nutrients calcium, iron and zinc are the most
commonly deficient minerals in the developing countries. Their deficiency in diej^ Combine with the low rates of
absorption has severe implications for growth and developing (Henry and
massy 2001). The diets of poor communities in developing countries tend to be based
on a local staple, which is often bulky and high in dietary fibre. Thus,
although the diets are
filling, they may have undesirable effects on the
bioavailability of already scare micro and macro nutrients. The
bioavailability of micronutrients such as tannins, phyates, oxalates and citrates
(Henry as massey 2001).
Anti-nutrition
factors in the rice grains are concentrated in the bran fraction (embroyo and aleurone layer). They include phytin (phytate, trypsifii inhibitor, oryzcystain and
haemagglutimin, Lectin. All the
anti-nutrients factors are protein and all except phytin are subjected to denaturation by heat (Juliano 1993). Phytate Fibre
rich food including both cereals and legumes, contains high levels of phytate or phytic acid. It is usually
located at the out layers of cereals.
During milling most of phytic acids is removed (Henry and massey, 2001).
Phytate is located in l-to-3um globoids in the aleurone and embryo protein
bodies as the potassium magnesin salt. Its sulphate groups can readily
be complex with cations such as calcium, zinc, and irons
with protein. It is heat stable and
is responsible for the
observed poorer mineral ia-r balance of
subjects feed brown rice diets in
comparison to that of
subject fed milled rice diets. (MiyoshieJ al,
1987). The inhibition seems to be close
dependent, with small amounts of
having a strong inhibitory effect.