Effect of blueberries on non-heme iron absorption in adult women

Abstract

Iron deficiency, the leading cause of anemia, can be exacerbated by dietary inhibitors such as polyphenols in fruits and vegetables. Despite their high polyphenol content, blueberries contain antioxidant compounds such as ascorbic acid and carotenoids, which are known to enhance iron absorption. This study aims to assess the net effect of blueberry consumption on non-heme iron absorption in healthy, non-menopausal women. Fourteen women aged 38–50 years, with contraception and a negative pregnancy test, participated in the study. After overnight fasting, the subjects were administered iron with or without fresh blueberries on four different intervention days. On day 1, the subjects received FeSO₄ solution as control (C); on day 2, FeSO₄ + 100 g of blueberry (B); on day 14, FeSO₄ + 100 g of blueberry + standardized breakfast (A); and on day 15, FeSO_{4 +} breakfast (D). All servings contained 5 mg of Fe labeled with radioactive isotopes (⁵⁵Fe, ⁵⁹Fe). Blood samples were taken on days 14 and 28 to measure the iron bioavailability and nutritional status. The iron bioavailability in the different groups was (geometric mean and range ±1 SD): C= 30.2 % (13.8–66.0 %), B= 6.8 % (2.1–21.7 %), A= 7.5 % (2.3–24.0 %), and D= 5.7 % (1.5–22.4 %); ANOVA for repeated measures F= 10.2 p < 0.0001 (Dunnett post hoc test: C vs. A, B, and D, p < 0.0001). In conclusion, this study found that fresh blueberries, with or without breakfast, significantly decreased non-heme iron absorption. Given the small sample size and the limited population studied, these findings should be considered preliminary and warrant confirmation in larger studies.