A recent analysis of 34 studies on the UK Biobank population, along with six meta-analyses evaluating blood-based biomarkers, found that fish oil has widespread health benefits, and is associated with just one adverse outcome. The findings were published in Prostaglandins, Leukotrienes, and Essential Fatty Acids.

The new analysis evaluated 60 health outcomes and found that there were 44 favorable associations related to a reduced risk for cardiovascular, neurodegenerative, inflammatory, and metabolic conditions. Meanwhile, there was one significant association that was unfavorable (an 18% increased risk of osteoarthritis) in this population.

“Healthy user bias is unlikely to explain these results: the breadth and consistency of favorable associations suggest genuine biological effects of omega-3 fatty acids,” the authors reported, noting that they included reviews that featured biomarkers of omega-3 status alongside the UK Biobank, which relied on food frequency questionnaires. “Together, these consistent findings across UK Biobank fish oil supplementation and biomarker-based meta-analyses support the hypothesis that higher omega-3 status, however achieved, is generally beneficial for health. Because of the wide variety of outcomes favorably linked with fish oil supplement use (and elevated omega-3 blood levels) it seems unlikely that a “healthy users bias” and not the bioactivity of omega-3 fatty acids themselves can explain all these relationships,” meaning that fish oil use isn’t simply a marker of a healthy lifestyle.  

“This review helps clarify that fish oil isn’t the liability some headlines have painted it to be,” said Bill Harris, PhD, president of the Fatty Acid Research Institute. “With strong biomarker-backed data showing consistent cardiometabolic and neurological associations, and minimal adverse signals, there’s real reason to consider omega-3 status as a foundational piece of long-term wellness.”