#596: Why Do Omega-3 Trials Show Mixed Results?

Omega-3 fatty acids (particularly EPA and DHA) have a long history in nutrition and cardiovascular medicine, yet the clinical trial literature is often perceived as inconsistent. This episode examines why some randomized trials show clear benefit while others show null or mixed findings, and how differences in trial design, dose, population risk, and outcome selection can materially change what we observe. A key theme is separating (1) the persistent cultural narratives around omega-3s (including origin stories that do not hold up well to modern evidence) from (2) the more precise, mechanistic and clinical questions about where supplemental EPA/DHA may reduce cardiovascular risk. The discussion focuses heavily on understanding heterogeneity: why "omega-3 supplementation" is not a single, uniform exposure, and why subgroup patterns (e.g., secondary prevention, higher baseline triglycerides, and higher doses) may explain much of the apparent conflict in the evidence. Note: This discussion is taken from a previous episode of the podcast. The audio has been remastered and improved, and now study notes and full transcript are available. Timestamps [04:10] Omega-3 historical context and Inuit studies [08:38] Mechanisms of omega-3 benefits [12:49] VITAL and ASCEND trials analysis [23:41] GISSI-Prevenzione trial insights [26:44] REDUCE-IT trial and residual risk [32:19] Significance of baseline triglycerides [37:57] 2018 Cochrane review [46:02] Hu et al. meta-analysis [01:00:27] Practical takeaways for omega-3 supplementation [01:03:55] Key ideas segment (premium subscribers only) Related Resources Go to episode page (with links to mentioned studies) Join the Sigma email newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Alan Flanagan's Alinea Nutrition Education Hub