Abstract
Prebiotics are compounds in food that benefit health via affecting the gut microbiome. Omega-3 fatty acids have been associated with differences in gut microbiome composition and are widely accepted to have health benefits, although recent large trials have been inconclusive. We carried out a 6-week dietary intervention comparing the effects of daily supplementation with 500 mg of omega-3 versus 20 g of a well-characterized prebiotic, inulin. Inulin supplementation resulted in large increases in Bifidobacterium and Lachnospiraceae. In contrast, omega-3 supplementation resulted in significant increases in Coprococcus spp. and Bacteroides spp, and significant decreases in the fatty-liver associated Collinsella spp. On the other hand, similar to the results with inulin supplementation which resulted in significant increases in butyrate, iso-valerate, and iso-butyrate (p < .004), omega-3 supplementation resulted in significant increases in iso-butyrate and isovalerate (p < .002) and nearly significant increases in butyrate (p < .053). Coprococcus, which was significantly increased post-supplementation with omega-3, was found to be positively associated with iso-butyric acid (Beta (SE) = 0.69 (0.02), P = 1.4 x 10-3) and negatively associated with triglyceride-rich lipoproteins such as VLDL (Beta (SE) = -0.381 (0.01), P = .001) and VLDL-TG (Beta (SE) = -0.372 (0.04), P = .001) after adjusting for confounders. Dietary omega-3 alters gut microbiome composition and some of its cardiovascular effects appear to be potentially mediated by its effect on gut microbial fermentation products indicating that it may be a prebiotic nutrient.
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Key Points
This study showed that six weeks of supplementation with 500 mg of omega-3 (providing 165 mg of EPA and 110 mg DHA) led to significant increases in Coprococcus spp. and Bacteroides spp, while decreases were also observed for Collinsella spp., which is associated with fatty-liver. There were significant changes in the levels of bacterial fermentation products following a 6-week intervention with omega-3 supplementation and the overall effects were comparable to inulin fiber supplementation supporting the role of omega-3 as a potential prebiotic. The current findings suggest that the cardiovascular benefits of omega 3 supplementation may be mediated by the gut microbiome. Significant decreases in abundance of the genus Collinsella were also found. This genus has been reported to be increased three-fold in people with non-alcohol fatty liver disease.