Fish oil and muscles: which outcome matters?
In this investigation
The question behind the fish purchase
I want small oily fish that tastes good, comes in a manageable portion and has a tolerable sodium label. My sardine and anchovy experiences are in the food record. The additional question is whether a concentrated fish-oil supplement would improve training.
A promising laboratory result
A 2011 trial randomized 16 adults aged at least 65; 15 were analyzed. Eight weeks of a product supplying 3.36 g EPA+DHA daily, versus corn oil, increased muscle protein synthesis in response to an intravenous amino-acid and insulin infusion. The change in that response differed between groups; resting synthesis did not improve. Muscle growth and strength were not tested. Reliant supplied capsules and funding; the authors reported no funder role in the study. This was a laboratory response, not a demonstration that adding fish to a meal builds more muscle. Smith et al., 2011.
A strength signal in older adults
A separate six-month trial randomized 60 adults aged 60–85 to the same EPA+DHA amount or corn oil, without a training program. Forty-four completed; one could not perform the strength tests. Between-group differences favored fish oil for thigh muscle volume, grip strength and a combined lifting-strength score. The fourth primary outcome, average isokinetic muscle power, did not differ significantly. Multiple primary tests and completer selection limit certainty. These results do not establish improved walking, fewer falls or a young lifter’s gains. GSK donated both study products; the authors reported no funder role. Smith et al., 2015.
Protein synthesis after eating and lifting
A 2016 trial randomized 20 young men; a sample-processing error left 19 for analysis. After eight weeks of fish oil supplying 4.4 g EPA+DHA daily or coconut oil, participants drank 30 g whey, with one leg having performed resistance exercise. Protein synthesis increased after feeding and exercise in both groups, with no detected additional fish-oil effect over three hours. Some signaling results differed, illustrating why a molecular change cannot substitute for the outcome being claimed. Gatorade supported the work and Glasgow Health Solutions supplied fish oil. McGlory et al., 2016.
Does this change the routine?
Compare longer young-lifter trials separately. These experiments do not establish shoulder treatment or canned-fish effects. No extra capsule purchase follows from this record; enjoyable fish remains a food choice.