Triglyceride Reduction
EPA and DHA reduce blood triglycerides, improve HDL cholesterol, lower blood pressure in hypertensive individuals, reduce arterial inflammation, and improve endothelial function. A 2021 systematic review and meta-analysis of 38 RCTs involving 149,000 participants confirmed that omega-3 fatty acids reduce cardiovascular mortality (RR 0.93), non-fatal myocardial infarction (RR 0.87), and major adverse cardiovascular events (RR 0.95)[2]. The effect is consistent across multiple trial designs and populations. The omega-3 index, a measure of DHA+EPA as a percentage of total red blood cell fatty acids, is increasingly recognized as a strong independent predictor of cardiovascular and all-cause mortality risk.
DHA is structurally essential to the brain and retina, it makes up roughly 20% of total fatty acids in the cerebral cortex. Sufficient dietary DHA supports neuronal membrane fluidity, synaptic signaling, and BDNF production. Deficiency is associated with accelerated cognitive decline, depression, and increased dementia risk. Population studies consistently link regular fish consumption to slower age-related cognitive decline. The evidence is strongest for observational associations; randomized trial results for cognitive outcomes are more mixed, likely because trials are shorter than the timescale over which dietary patterns influence brain structure.
EPA is the primary driver of omega-3’s anti-inflammatory effects. It competes with arachidonic acid for cyclooxygenase enzymes, shifting eicosanoid production from pro-inflammatory (PGE2, TXA2) toward anti-inflammatory (PGE3, TXA3) species. Regular consumption reduces circulating CRP, IL-6, and TNF-alpha. Higher blood omega-3 levels are associated with longer telomeres in observational studies, a mechanistically plausible connection given that oxidative stress and inflammation are key drivers of telomere attrition.
Wild salmon, sardines, anchovies, herring, and mackerel (Atlantic or Pacific, not king) offer the highest omega-3 density with the lowest mercury burden. King mackerel, swordfish, shark, and tilefish accumulate mercury and should be limited. Canned sardines and mackerel are cost-effective options with levels of omega-3 comparable to fresh fish. Wild salmon has a higher omega-3 content than farmed, though farmed Atlantic salmon still provides meaningful EPA and DHA. Aim for 2-3 servings per week (100-150g each) to achieve levels associated with reduced cardiovascular risk. For people who dislike fish, algae-derived DHA and EPA supplements avoid mercury entirely and are the only plant-based source of bioavailable long-chain omega-3s.