Regular Consumption of a High-Phytate Diet Reduces the Inhibitory Effect of Phytate on Nonheme-Iron Absorption in Women with Suboptimal Iron Stores

Background: High-phytate (HP) consumption is a concern in developing countries because of the high prevalence of iron deficiency in these countries. Objective: We investigated whether habitual consumption of an HP diet reduces the inhibitory effect of phytate on nonheme-iron absorption. Methods: Thirty-two nonanemic females, 18–35 y of age, with normal body mass index but with suboptimal iron stores (serum ferritin, #30 mg/L), were matched for serum ferritin concentration and randomly assigned to HP and low-phytate (LP) groups, in a parallel design study. Each subject consumed HP or LP foods with at least 2 of their daily meals for 8 wk, resulting in a change in phytate intake (from 718 to 1190 mg/d in the HP group and 623 to 385 mg/d in the LP group). The serum iron response over 4 h after a test meal containing 350 mg of phytate was measured at baseline and postintervention. Ferritin, transferrin receptor, and hepcidin concentrations were measured at baseline and 8 wk. Results: Twenty-eight subjects completed the study (n = 14 per group). The serum iron response to the test meal increased in the HP group at postintervention, resulting in a 41% increase in the area under the curve (AUC; P < 0.0001). However, no effect was observed in the LP group (21% decrease in AUC; P = 0.76). The postintervention serum iron response was lower (P < 0.0001) in the LP group than in the HP group after controlling for the baseline serum iron response and hepcidin concentration, reflecting in a 64% lower AUC. Conclusions: We found that habitual consumption of an HP diet can reduce the negative effect of phytate on nonhemeiron absorption among young women with suboptimal iron stores. Future studies are needed to explore possible mechanisms. This trial was registered at clinicaltrials.gov as NCT02370940. J Nutr doi: 10.3945/jn.114.209957.