The effects of fat loss after bariatric surgery on inflammation, serum hepcidin, and iron absorption: a prospective 6-mo iron stable isotope study.

BACKGROUND: Iron deficiency is common in obese subjects. This may be due to an increase in serum hepcidin and a decrease in iron absorption from adiposity-related inflammation.

OBJECTIVE: We evaluated whether weight and fat loss in obese subjects would decrease inflammation and serum hepcidin and thereby improve iron absorption.

DESIGN: We performed a 6-mo prospective study in obese [body mass index (in kg/m2 ) ≥35 and <45] adults who had recently undergone laparoscopic sleeve gastrectomy. At 2 and 8 mo postsurgery, subjects consumed a test drink with 6 mg 57 Fe as ferrous sulfate and were intravenously infused with 100 μg 58 Fe as iron citrate. We then compared erythrocyte incorporation of iron isotopic labels, changes in body composition, iron status, hepcidin, and inflammation at each time point.

RESULTS: Forty-three subjects were studied at baseline, and 38 completed the protocol (32 women and 6 men). After 6 mo, total body fat, interleukin IL-6, and hepcidin were significantly lower (all P < 0.005). In iron-deficient subjects (n = 17), geometric mean (95% CI) iron absorption increased by 28% [from 9.7% (6.5%, 14.6%) to 12.4% (7.7%, 20.1%); P = 0.03], whereas in iron-sufficient subjects (n = 21), absorption did not change [5.9% (4.0%, 8.6%) and 5.6% (3.9%, 8.2%); P = 0.81].

CONCLUSION: Adiposity-related inflammation is associated with a reduction in the normal upregulation of iron absorption in iron-deficient obese subjects, and this adverse effect may be ameliorated by fat loss. This protocol was approved by the ethics committees of Wageningen University, ETH Zurich, the University of Monterrey, and the Federal Commission for the Protection against Sanitary Risks, and registered at clinicaltrials.gov as NCT01347905.