Low-phytate wholegrain bread instead of high-phytate wholegrain bread in a total diet context did not improve iron status of healthy Swedish females: a 12-week, randomized, parallel-design intervention study

Purpose: To investigate the effects of eating wholegrain rye bread with high or low amounts of phytate on iron status in women under free-living conditions. Methods: In this 12-week, randomized, parallel-design intervention study, 102 females were allocated into two groups, a high-phytate-bread group or a low-phytate-bread group. These two groups were administered: 200 g of blanched wholegrain rye bread/day, or 200 g dephytinized wholegrain rye bread/day. The bread was administered in addition to their habitual daily diet. Iron status biomarkers and plasma alkylresorcinols were analyzed at baseline and post-intervention. Results: Fifty-five females completed the study. In the high-phytate-bread group (n = 31) there was no change in any of the iron status biomarkers after 12 weeks of intervention (p > 0.05). In the low-phytate bread group (n = 24) there were significant decreases in both ferritin (mean = 12%; from 32 ± 7 to 27 ± 6 µg/L, geometric mean ± SEM, p < 0.018) and total body iron (mean = 12%; from 6.9 ± 1.4 to 5.4 ± 1.1 mg/kg, p