Effect of chili and turmeric on human iron absorption

Iron deficiency is a major public health problem in Asia where habitual diets are plant based and are rich in spices and herbs. Chili and turmeric are common spices in indigenous diets across the tropical belt. Being rich in phenolic compounds they may bind Fe in the intestine and inhibit Fe absorption. Three experiments were conducted in healthy women (10 women /study) to assess the effect of chili and turmeric on iron absorption from a rice based meal with vegetables. Iron absorption was determined by erythrocyte incorporation of stable isotope labels ( 57 Fe / 58 Fe) using a randomized cross‐over design. Chili (14 g fresh weight) containing 25 mg polyphenols inhibited Fe absorption by 38 % (6 % with chili vs. 9.7% without chili, p = 0.0017). No significant effect on Fe absorption was observed for turmeric (0.5 g dry powder) containing 50 mg polyphenols (p = 0.91). A potential effect of chili on gastric acid secretion was indirectly assessed by comparing Fe absorption from acid soluble 57 Fe pyrophosphate relative to water soluble 58 FeSO 4 from the same meal in presence or absence of chili. No indications for an enhancing effect of chili on gastric acid secretion was observed (relative Fe bioavailability with chili 5.4% vs. 6.4% without chili, p = 0.47). We conclude that chilli can reduce iron absorption significantly with iron binding through polyphenols as the primary mechanism of action. (Supported by International Atomic Energy Agency)