Omega-3 Long-Chain Polyunsaturated Fatty Acid Supplementation Did Not Reduce Inflammation to Improve Iron Absorption...

Young South African women face a double-burden of overweight or obesity and iron deficiency, with the former predicting the latter. Omega-3 long-chain polyunsaturated fatty acid (LCPUFA) supplementation can reduce inflammation. It is uncertain if this effect extends to adiposity-related inflammation, thereby reducing hepcidin secretion and improving iron absorption.

Using stable iron isotopes, we determined the effect of omega-3 LCPUFA supplementation on fractional iron absorption (FIA) from a meal containing iron as ferrous sulfate without and with ascorbic acid (AA).

In this single-blind, uncontrolled, before-after intervention stable isotope study, 30 South African women aged 18-35 y with body mass index ≥28 kg/m²_, systemic inflammation, and a low omega-3 LCPUFA status, consumed a noninhibitory meal containing 6 mg iron, without and with AA, before and after 3 mo of daily supplementation with 2.1 g omega-3 LCPUFA. At baseline and endpoint, we measured FIA 14 d after consumption of the second meal, iron and inflammation markers, hepcidin, and omega-3 index.

At baseline and endpoint, addition of AA significantly improved FIA from the meal. Median (IQR) FIA before compared with after supplementation was not different for the meal without AA [9.7 (4.3-24.6)% compared with 11.8 (2.8-22.3)%; P = 0.962] nor the meal with AA [27.5 (10.6-43.8)% compared with 30.8 (9.6-60.9)%; P = 0.249]. Supplementation increased the omega-3 index from 4.61 (4.10-5.11)% to 5.97 (5.48-8.16)% (P < 0.001), but did not reduce hepcidin or improve the inflammation and iron status markers. In multiple linear regression analyses, hepcidin was a stronger predictor of FIA than AA.

Addition of AA to the test meal, rather than omega-3 LCPUFA supplementation, improved iron absorption in South African women with overweight or obesity. Despite an increase in omega-3 index after omega-3 LCPUFA supplementation, it remained suboptimal, possibly explaining the lack of reduction in inflammation and hepcidin concentrations. This study was registered at clinicaltrials.gov as NCT05220735 (https://clinicaltrials.gov/study/NCT05220735?cond=obesity&term=iron%20absorption&rank=4).