Iron absorption from experimental infant formulas based on pea (Pisum sativum)-protein isolate:: the effect of phytic acid and ascorbic acid

Infant formula based on pea (Pisum sativum)-protein isolate has been suggested as an alternative to soyabean formula in countries where soyabean is not a native crop, or when soyabean protein cannot be used due to allergic reactions or intolerances. In the present study, Fe absorption from experimental infant formulas based on pea-protein isolate was measured in healthy non-anaemic young women. The influence of phytic acid and ascorbic acid on Fe absorption was evaluated, using a stable-isotope technique based on incorporation of Fe stable-isotope labels into erythrocytes 14 d after administration. Geometric mean Fe absorption increased from 20.7 (+1SD 41.6, -1SD 10.3) % to 33.1 (+1SD 58.6, -1SD 18.7) %; (P < 0.0001; n 10) after enzymic degradation of virtually all phytic acid. Doubling the molar ratio Fe:ascorbic acid from 1 : 2.1 to 1 : 4.2 in the infant formula with native phytic acid content also increased Fe absorption significantly (P < 0.0001; n 10); geometric mean Fe absorption increased from 14.8 (+1SD 32.1, -1SD 6.8) % to 22.1 (+1SD 47.2, -1SD 10.4) %. These results confirm the inhibitory and enhancing effects of phytic acid and ascorbic acid respectively on Fe absorption, but also indicate relatively high fractional Fe absorption from the pea-protein-based formulas. After adjusting for differences in Fe status, our data indicate that Fe absorption from dephytinised pea protein might be less inhibitory than dephytinised soyabean protein as measured in a previous study (Hurrell et al. 1998).