In Overweight Women, Adiposity-related Inflammation and Serum Hepcidin are Increased, Dietary Iron Bioavailability is decreased and Ascorbic Acid has Only a Negligible Enhancing Effect on Iron Bioavailability.

Objectives: Many countries are struggling with the double burden of malnutrition. Iron deficiency is prevalent in overweight and obese (OW/OB) subjects, likely due to adiposity-related inflammation increased hepcidin and decreased iron absorption. Because hepcidin reduces iron efflux from the basolateral enterocyte, whether luminal enhancers of iron absorption, like ascorbic acid (AA), would be effective in OW/OB subjects is uncertain. We compared iron bioavailability (FeB) from non-inhibitory meals with and without AA in normal weight (NW), OW, and OB women. Methods: In a randomized crossover study in young women (NW=25, OW=20 and OB=19), FeB from a test meal without (A) and with (B) AA was measured by using erythrocyte incorporation of Fe isotopic labels at 14d. Results: Inflammation and serum hepcidin were lower in the NW versus OW and OB. FeB from meal A was 20% in NW versus 12% in OW and 12% in OB (NW vs OW/OB: P=0.049). FeB from meal B was 28% in NW versus 15% in OW and 16% in OB (NW vs OW/OB: P=0.004). The %increase in FeB comparing A to B was greater in the NW (P<0.001) than in OW (P=0.178) or OB (P=0.008). Higher hepcidin predicted lower FeB (A:β=-0.458, P<0.001) Conclusions: Serum hepcidin is higher and FeB is lower in OW/OB compared to NW subjects. Moreover, the enhancing effect of AA on FeB in OW/OB subjects is blunted, consistent with the hypothesis that increased hepcidin in OW/OB limits iron absorption. The widespread increase in obesity may limit current dietary strategies to improve FeB in anemic women.

Strategies to Enhance Iron Absorption from Tef-injera in Young Women.

Objectives: Tef is a cereal indigenous to Ethiopia. The flour obtained is mostly used to produce a soft, pancake-like sourdough-bread, called injera. Since it contains considerable amounts of phytate, iron bioavailability from this Ethiopian staple is believed to be limited. We investigated different strategies to improve iron absorption from tef-injera. These included decreasing the phytate:iron molar ratio by simultaneously enhancing the iron content and lowering the phytate content during fermentation, by the addition of the enzyme phytase and by partially replacing tef by flours exhibiting high phytase activity. Additionally the impact of substituting FeSO4 by the alternative fortificant NaFeEDTA on bioavailability in humans was tested. Methods: Iron absorption was measured with stable isotopes in 2 groups of 17 young women in single-meal studies, serving modified tef-injera meals with tomato sauce in a cross-over design. Results: Iron absorption from traditional tef-injera was low (1.4%) and did not substantially increase with NaFeEDTA but approximately doubled (p<0.01) to 3.6% and 3.1% by reducing the phytate:iron molar ratio from 4.4 to 1.5 and 0.2 in variations with 10% wheat and purified phytase, respectively. Conclusions: Iron absorption was generally low from all meals and fortification of tef-injera with NaFeEDTA did not increase iron bioavailability compared to FeSO4, suggesting other factors, such as proteins or polyphenols, having an additional negative influence. Nevertheless, reducing the phytate content of tef-injera by either co-fortification with wheat or addition of purified phytase more than doubled iron bioavailability from this Ethiopian staple food and would provide additional absorbable iron.