Household dietary strategies to enhance the content and bioavailability of iron, zinc and calcium of selected rice- and maize-based Philippine complementary foods.

Philippine complementary foods are predominantly plant-based, with a low content of readily available iron, zinc, and calcium, and a relatively high amount of phytate, a potent inhibitor of mineral absorption. Some of the phytate is water soluble, and hence can be removed by soaking. In this study we have compared the iron, zinc, and calcium content, and estimated iron and zinc bioavailability of rice- and maize-based Filipino complementary foods prepared with and without soaking and/or enrichment with chicken liver, egg yolk, small soft-boned fish, and mung bean grits. Analysis of iron, zinc, and calcium were performed by atomic absorption spectrometry, and phytate (based on hexa-(IP6) and penta-inositol phosphate (IP5) by HPLC; corresponding [Phy]/[Fe] and [Phy]/[Zn] molar ratios were calculated as predictors of iron and zinc bioavailability. Addition of chicken liver, followed by egg yolk, resulted in the greatest increases in iron and zinc content for both the rice- and maize-based complementary foods, whereas addition of small dried fish with bones had the greatest effect on calcium. The IP5 + IP6 content and [Phy]/[Zn] molar ratios were higher in the maize- than rice-based complementary foods, and were reduced by soaking, although only the maize plus mung bean grits, with and without soaking, had [Phy]/[Zn] molar ratios above 15. Enrichment with animal protein or soaking has the potential to enhance the content of absorbable iron, zinc, and probably calcium to varying degrees in rice- and maize-based Philippine complementary foods.