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.

ABSTRACT

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 (Aβ=-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.