Comparative performance of pearl millet-and sorghum-based diets vs. wheat-and rice-based diets for trace metal bioavailability

Pearl miller and sorghum offer a cheap source of energy compared to wheat a nd rice and are widely consumed by rural communities in many parts of the w orld. Due to the low consumption of vegetables and animal foods, millets al so are the major suppliers of micronutrients especially for low-income grou ps. It is of prime importance to study how millets perform in terms of bioa vailable contents of trace metals. Investigations were carried out using we anling mice which offer a model for the initial testing of bioavailability of trace metals before human trials. Four isocaloric diets differing only i n the type of cereal, i.e pearl millet, sorghum, wheat and rice, were prepa red representing habitual dietary patterns observed by National Nutrition M onitoring Bureau (NNMB) of India. Mice were allocated randomly to 4 groups of 8 mice each, and housed individually in metal free metabolic cages. A fi fth group of 8 mice fed a balanced synthetic diet served as control. All th e groups were fed ad libitum. The absorption of zinc and iron averaged for 3 periods of 5 days each was significantly higher for the wheat and pearl m illet group than for the other 2 experimental groups (p<0.05), as were also the levels of liver zinc and iron. The weight gain was also highest (6.9 /- 1.2 g) in the pearl millet group as compared to sorghum (1.58 +/- 0.59 g ), wheat (1.66 +/- 1.27 g) and rice (-0.72 +/- 0.62 g) groups. The levels o f liver copper were comparable in all the 5 groups. These results further c onfirm our earlier in vitro results indicating the superiority of pearl mil let but not sorghum in bioavailability of zinc and iron.