In vitro availability of iron and zinc from some Indian vegetarian diets: correlations with dietary fibre and phytate

Sixty vegetarian diets consumed by children, adolescents, adults and older adults from rural families living in northern India were studied for Fe and Zn availability (in vitro). The method measures ionizable Fe at pH 7.5 in the diets, simulating conditions prevailing in the intestine and correlates highly with per cent Fe absorption in humans. Zinc availability is measured in the same sample by following the same procedure based on the fact that most of the Zn is absorbed in the intestine under similar conditions. The availability of these minerals was poor, ranging from 7.8 to 8.7% and from 3.3 to 4.4% for Zn and Fe, respectively. The poor availability could be related to the compositions of these diets, which included mainly cereals, and these contributed high amounts of phytate as well as fibre. A negative and significant correlation coefficient between dietary fibre or phytate content and Fe and Zn availability in these diets suggests some possible interactions.