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 μg/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 nonheme-iron 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.