Background: Visceral adipose tissue (VAT) and truncal fat predict cardiometabolic disease. Intervention trials suggest that saturated fatty acids (SFA), e.g. palmitic acid, promote abdominal and liver fat storage whereas polyunsaturated fatty acids (PUFA), e.g. linoleic acid, prevent fat accumulation. Such findings require investigation in population-based studies of older individuals. We aimed to investigate the relationships of serum biomarkers of PUFA intake as well as serum levels of palmitic acid, with abdominal and total adipose tissue content.
Methods: In a population-based sample of 287 elderly subjects in the PIVUS cohort, we assessed fatty acid composition in serum cholesterol esters (CE) and phospholipids (PL) by gas chromatography and the amount of VAT and abdominal subcutaneous (SAT) adipose tissue by magnetic resonance imaging (MRI), liver fat by MR spectroscopy (MRS), and total body fat, trunk fat and leg fat by dual-energy X-ray absorptiometry (DXA). Insulin resistance was estimated by HOMA-IR.
Results: VAT and trunk fat showed the strongest correlation with insulin resistance (r = 0.49, P < 0.001). Linoleic acid in both CE and PL was inversely related to all body fat depots (r = -0.24 to -0.33, P < 0.001) including liver fat measured in a sub-group (r = -0.26, P < 0.05, n = 73), whereas n-3 PUFA showed weak inverse (18:3n-3) or positive (20:5n-3) associations. Palmitic acid in CE, but not in PL, was directly correlated with VAT (r = 0.19, P < 0.001) and trunk fat (r = 0.18, P = 0.003). Overall, the significant associations remained after adjusting for energy intake, height, alcohol, sex, smoking, education and physical activity. The inverse correlation between linoleic acid and VAT remained significant after further adjustment for total body fat.
Conclusions: Serum linoleic acid is inversely related to body fat storage including VAT and trunk fat whereas palmitic acid was less consistently but directly associated, in line with recent feeding studies. Considering the close link between VAT and insulin resistance, a potential preventive role of plant-based PUFA in VAT accumulation warrants further study.
Keywords: Adipose tissue distribution; Body fat; Fatty acid; Linoleic acid; Palmitic acid; Polyunsaturated fat; Saturated fat; Visceral adipose tissue.