Omega-3 Fatty Acid Supplementation and Fractional Iron Absorption in Obese South African Women
Condition: Obesity
MeSH terms: Obesity
Study type: Interventional

Summary: 
      In South Africa the prevalence of obesity in women of reproductive age is high; these women
      also have a high risk for iron deficiency (ID). Obesity is associated with low-grade systemic
      inflammation, which was shown to increase the expression of hepcidin, leading to a reduction
      in duodenal iron absorption. Thus, alleviating the sub-clinical inflammation associated with
      obesity could improve iron absorption and status. Supplementation with n-3 long-chain
      polyunsaturated fatty acids (LCPUFA) has been shown to reduce inflammation in obese
      individuals. A stable iron isotope study will be performed to investigate the effect of n-3
      LCPUFA supplementation on fractional iron absorption in obese South African women.
    

Detailed description: 
      Iron deficiency (ID) and iron-deficiency anaemia (IDA) remain a major public health problem
      in low- and middle-income countries (LMICs). Women of reproductive age are at high risk of
      developing ID due to loss of iron through menstruation. Furthermore, inadequate iron status
      at conception and during pregnancy can have detrimental effects on the developing offspring.
      In addition to ID, the prevalence of obesity is increasing globally, including in LMICs.
      South Africa is a country with a high prevalence of obesity, especially in women of
      reproductive age (36 %), and a persistent burden of ID despite a mandatory maize meal and
      wheat flour fortification programme. Obesity is a condition associated with low-grade
      systemic inflammation. Inflammation increases the expression of hepcidin, leading to a
      reduction in duodenal iron absorption. Previous studies have shown that iron absorption
      differs between normal weight and obese individuals, and that the enhancing effect of
      ascorbic acid on iron absorption is lower in obese subjects. A possible explanation is the
      different sites of action of ascorbic acid and hepcidin on the enterocytes: Ascorbic acid
      enhances iron transport into enterocytes at the luminal side (via divalent metal
      transporter-1), while hepcidin reduces iron absorption by ferroportin inhibition at the
      basolateral membrane of the enterocyte. Thus, in obese individuals, an intervention at the
      basolateral membrane of the enterocyte will be needed. Supplementation with n-3 long-chain
      polyunsaturated fatty acids (LCPUFA) has been shown to exert cardiometabolic benefits, and to
      reduce inflammation in obese individuals.

      The aim of this study is to investigate the effect of n-3 LCPUFA supplementation on
      fractional iron absorption in obese South African women of reproductive age. As a secondary
      objective, this study will determine association between omega-3 fatty acid status,
      inflammation and iron status in obese South African women. The hypothesises are: 1)
      fractional iron absorption will increase following n-3 LCPUFA supplementation; 2) iron
      absorption will further increase in the presence of ascorbic acid following n-3 LCPUFA
      supplementation.

      After screening, apparently healthy, non-anaemic, obese South African women of African
      descent, aged 18 to 35 years, with low-grade inflammation and a low n-3 LCPUFA status, will
      receive daily oral fish oil (2.1 g of n-3 LCPUFA) capsules for three months. Iron status
      indices, inflammatory markers, hepcidin and omega-3 fatty acid index will be assessed at
      screening. The same variables will be emasured again at baseline and endpoint, in addition to
      erythrocyte total phospholipid fatty acid composition. Iron absorption will be determined
      from test meals with and without ascorbic acid using the oral stable isotope method, before
      (baseline) and after (endpoint) supplementation with n-3 LCPUFA.
    

Intervention name(s): Omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA)
Intervention type(s): Dietary Supplement
Intervention description(s): 3 three fish oil capsules providing 2.1 g n-3 PUFA; 1.27 g Docosahexanoic acid (DHA) and 0.86 g Eicosapentanoic acid (EPA) capsules.
The absorption study test meals will consist of white bread with butter and honey, 6mg of labeled iron as ferrous sulfate and 300 g of distilled water. The meal will be given on two days without and with ascorbic acid. The test meals without ascorbic acid will contain 6 mg 57Fe as ferrous sulfate whereas the meals containing ascorbic acid will contain 6 mg 58Fe as ferrous sulfate.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Fractional iron absorption; Inflammation; Omega-3 fatty acids