Maize kernel gallic acid concentrations significantly influence iron bioavailability

Iron deficiency in resource‐poor households is commonly attributed to an inadequate dietary intake of bioavailable iron due to the presence of iron inhibitors and/or the absence of iron absorption enhancers in the diet. Our objective was to determine factors in maize kernels that influence iron bioavailability. Kernels from 24 recombinant inbred maize lines (RILs) of the Intermated B73 and Mo17 population (IBM) (samples from a single location) were analyzed for their mineral composition, polyphenol profile, phytate levels and iron bioavailability. Iron bioavailability was determined using an in vitro digestion/Caco‐2 cell model. Ascorbic acid was added to digests at a 1:20, Fe: ascorbate molar ratio. Inductively coupled argon‐plasma emission spectroscopy was used to determine kernel‐mineral concentrations. High‐pressure liquid chromatography was used to determine phytate levels and polyphenol profiles. Iron concentrations ranged from 17.96 to 26.3 μg/g; phytate levels ranged from 5.0to 8.3 μmoles/g. Iron to phytate molecular ratios ranged from 12.9 to 24.3. Significant differences in iron bioavailability exist among the maize lines tested (ANOVA, P‐value ≤ 0.02). Iron, phytate and Fe: ascorbic acid ratio, were not correlated to iron bioavailability. Polyphenols detected included gallic acid, protocatechuic acid, ferulic acid, catechin, epigallacatechin and ρ‐coumaric acid. Regression analysis of these polyphenols indicated that only gallic acid concentration was significantly (P value ≤ 0.05) correlated with iron bioavailability and was responsible for 30% of the variance in maize‐kernel iron bioavailability.