Fish oil and muscle: new review finds no clear benefit for healthy adults

Omega-3 supplements are often mentioned in healthy-aging circles as a way to protect muscle. A new review of the best available trials, published in the journal Nutrition on September 14, 2026, found no clear evidence that this is the case in healthy adults. The researchers also rated the quality of the evidence as very low, so the honest answer for now is “we can’t tell”.

What the researchers did

A research team that includes academics from Brazilian universities searched four research databases (PubMed, Embase, CINAHL and Web of Science) for studies up to February 25, 2026. They included only randomized, placebo-controlled trials of omega-3 fatty acids taken on their own (not mixed with other supplements) in healthy adults without obesity. They then pooled the results in a meta-analysis, which combines several studies to get a clearer overall picture. They checked the risk of bias in each trial using a standard tool (Cochrane RoB 2) and rated how certain the evidence was using the GRADE system.

Four studies could be pooled for fat-free mass (everything in the body that isn’t fat, mainly muscle, bone and water) and eight studies for muscle strength.

What they found

• Fat-free mass: no clear difference between omega-3 and placebo. The pooled result was a standardized mean difference (SMD) of 0.26, with a 95% confidence interval of -1.14 to 1.66 (P = 0.60). That range is very wide and includes both a benefit and a drop.
• Muscle strength: again no clear difference. SMD -0.02 (95% CI -0.38 to 0.34; P = 0.92). A value close to zero means the omega-3 and placebo groups ended up much the same.
• Certainty of evidence: very low.

The authors concluded that current evidence is insufficient to say that omega-3 supplements improve fat-free mass or muscle strength in healthy adults.

What this means for you

What this means for you

• What was studied: omega-3 supplements (fish-oil-type fatty acids) versus placebo, looking only at muscle mass and strength. We did not see the doses used in the abstract.
• Who was studied: healthy adults without obesity.
• What it shows: no clear muscle benefit, but also not proof of “no effect”, because there were few trials and the results were imprecise.
• What it does not cover: this review says nothing about omega-3 and the heart, brain or other areas of health.
• Evidence strength (our simple scale: very low, low, moderate, high): very low, which is the authors’ own rating.
• Read more in our beginner’s guide to omega-3.

How strong is this evidence?

Pooling randomized trials is a strong approach in principle. In practice, this analysis rested on very few trials (four for muscle mass, eight for strength), and the confidence interval for muscle mass was extremely wide, which is why the authors rate the certainty as very low. A “no clear effect” finding with low certainty is different from a clear “no effect”. We read the abstract and the PubMed record only, so we cannot report participant numbers, doses or trial lengths. The authors declare no competing interests; we did not see a funding statement.

Sources

• Silva AMF, Simões MO, Artioli GG, et al. Omega-3 supplementation shows no clear benefit for fat-free mass or muscle strength in healthy adults: a systematic review and meta-analysis of randomized controlled trials. Nutrition, published September 14, 2026. DOI: 10.1016/j.nut.2026.113378 / PubMed 42735611 (abstract and PubMed record read; full text not read)

This article is for information only and is not medical advice. Speak to a healthcare professional before changing medication or supplements.