Fish oil boosts muscle growth from exercise in older women

Omega 3 from fish oil could help older women avoid loss of muscle mass, strength, and function by enhancing activity-induced muscle growth. Unfortunately, men do not seem to get this benefit from supplementation, but the positive effects on muscles are not lacking in their case either.

It was way back in 2012 when Stuart Gray, a researcher at the University of Aberdeen (UK) at the time, announced during the British Science Festival the first study that would monitor changes in muscle function and mass achievable in old age by combining exercise with the intake of Omega-3 rich fish oil.

Since then, several studies have investigated the benefits of these fats for muscles, suggesting that it is not always necessary to increase their mass in order to improve strength and function, that the effects on the latter are sex-specific, and that, in any case, these are allied nutrients to counteract a highly desired but rather frequent phenomenon during aging: sarcopenia. 

Protecting muscles from aging

In fact, the human body is made up of a large amount of skeletal muscle, which not only provides the ability to perform various movements but is also important for overall health throughout life.

Unfortunately, however, during the natural aging process the size of muscles decreases by between 0.5 and 2 percent each year, contributing precisely to what is known as sarcopenia.      

The latter consists of loss of muscle mass and strength and can significantly reduce the quality of life, so much so that it can lead to loss of part of individual independence during old age.

Exercise can help counteract muscle mass loss, but unfortunately, the effectiveness of a training-based approach also declines with advancing age; finding alternative ways to protect muscles could help overcome this obstacle.

The combined action of exercise and Omega-3

Both a preliminary study by researchers at the University of Aberdeen and research published in the American Journal of Clinical Nutrition by a group of experts at the Federal University of Parana (Brazil) had suggested that in older women the benefits of exercise were greater if Omega-3-rich fish oil was taken during exercise.

The latter are essential fatty acids for the body, where they perform both a structural function (i.e., they are among the molecules that form cellular structures and, therefore, tissues and organs) and beneficial health activities. Among the best known are their ability to reduce inflammation and protect the cardiovascular system by regulating triglyceride levels. 

But Omega-3s are not only good for the heart: many other organs and tissues could also benefit from increased intake of these fats, including those in the nervous system, joints and muscles. 

So Gray and colleagues planned to shine a spotlight on the possible benefits exerted by these nutrients on muscle tissue, with the ultimate goal of contributing to the development of new treatments to combat sarcopenia.

Not only women

The analyses, hitherto conducted mostly on women, were extended to men as well. Indeed, the research announced by Gray was set up to involve both women and men over the age of 65 in an 18-week exercise program; only half of the participants would receive fish oil, while the others would be assigned to take a placebo.

Gray explained that he expects benefits based on several mechanisms, first and foremost the anti-inflammatory action of the Omega-3s contained in fish oil. During old age, in fact, inflammation levels increase, interfering with the ability of muscles to increase their mass and strength. 

"The anti-inflammatory properties of fish oil could reduce this inflammation and thus inhibit this interference," Gray explained, adding that "Omega 3 in fish oil could also help make muscles more fluid and [increase] protein levels that enable muscle mass gain."

In contrast, other authors have pointed out that increased muscle protein synthesis could be a consequence of increased nutrient flow to the muscles.

What effect on muscle mass?

Over the ensuing years, Gray, now a professor of Muscle and Metabolic Health at the University of Glasgow (UK), signed several scientific publications on the benefits of fish oil for muscles.

In 2018, writing in the pages of Current Opinion in Clinical Nutrition and Metabolic Care together with Bettina Mittendorfer of the Washington University School of Medicine (St. Louis, U.S.), the expert pointed out that "results from several recent studies show that in sedentary elderly people, dietary supplementation with Omega 3 polyunsaturated acids from fish oil stimulates muscle protein synthesis and improves muscle mass and function, and that in the elderly, it enhances resistance training-induced increases in muscle strength."

In 2024, in a review of the scientific literature published in the same journal, Gray and coauthors wrote instead that "Systematic reviews and meta-analyses of randomized controlled trials report small but clinically relevant effects of oral intake of Omega 3 polyunsaturated fatty acids on strength, while variable results on changes in muscle mass and physical function have been reported."

In the same year, a group of experts from Hosei University in Tokyo, Japan, attempted to draw conclusions from studies that, like the one announced in 2012 by Gray, combined resistance training with Omega 3 intake. 

"The results of the meta-analysis revealed that Omega-3 fatty acid supplementation and resistance training significantly improved muscle strength compared with the control group," the experts explained, adding, however, that "no significant effects on muscle mass were observed."

Omega 3 and muscles: possible specific benefits for women

On the other hand, the very research results announced by Gray at the British Science Festival, published in 2017 in the American Journal of Clinical Nutrition, point to possible muscle mass benefits specifically for women. 

In fact, the data collected found an increase in both muscle mass and muscle function only in women, while another well-known benefit of Omega 3 (the reduction of triglycerides) was found to be independent of gender.

"After endurance training," Gray and coworkers explain, "supplementation with long-chain omega-3 polyunsaturated fatty acids (those found in fish oil, ed.) increase in muscle function and quality in older women, but not in older men."

In addition, studies collected in the scientific literature suggest that more than 2 grams of Omega 3 per day are needed to increase muscle mass and that these fats can improve muscle strength and function even without increasing muscle mass.

Thus, on the one hand, Omega 3 from fish oil could exert benefits on muscles that are independent of increased muscle mass; on the other hand, it would also be possible to increase the latter with an appropriate supplementation protocol of at least 2 grams of Omega 3 per day, especially in the case of women.

When all their results are analyzed simultaneously, the heterogeneity of the studies conducted to date, which have used different supplementation protocols involving both men and women, could mask dose-dependent and sex-specific benefits.

Further research will confirm these conclusions and clarify the exact mechanism by which Omega 3 could promote muscle mass gain.

Bibliographic references:

Da Boit M, Sibson R, Sivasubramaniam S, Meakin JR, Greig CA, Aspden RM, Thies F, Jeromson S, Hamilton DL, Speakman JR, Hambly C, Mangoni AA, Preston T, Gray SR. Sex differences in the effect of fish-oil supplementation on the adaptive response to resistance exercise training in older people: a randomized controlled trial. Am J Clin Nutr. 2017 Jan;105(1):151-158. doi: 10.3945/ajcn.116.140780

Gray SR, Mittendorfer B. Fish oil-derived n-3 polyunsaturated fatty acids for the prevention and treatment of sarcopenia. Curr Opin Clin Nutr Metab Care. 2018 Mar;21(2):104-109. doi: 10.1097/MCO.0000000000000441

Huang YH, Chiu WC, Hsu YP, Lo YL, Wang YH. Effects of Omega-3 Fatty Acids on Muscle Mass, Muscle Strength and Muscle Performance among the Elderly: A Meta-Analysis. Nutrients. 2020 Dec 4;12(12):3739. doi: 10.3390/nu12123739

Phillips N, Gray SR, Combet E, Witard OC. Long-chain n -3 polyunsaturated fatty acids for the management of age- and disease-related declines in skeletal muscle mass, strength and physical function. Curr Opin Clin Nutr Metab Care. 2024 Mar 1;27(2):98-105. doi: 10.1097/MCO.0000000000000986

Timraz M, Binmahfoz A, Quinn TJ, Combet E, Gray SR. The Effect of Long Chain n-3 Fatty Acid Supplementation on Muscle Strength in Older Adults: A Systematic Review and Meta-Analysis. Nutrients. 2023 Aug 14;15(16):3579. doi: 10.3390/nu15163579

Uchida Y, Tsuji K, Ochi E. Effects of omega-3 fatty acids supplementation and resistance training on skeletal muscle. Clin Nutr ESPEN. 2024 Jun;61:189-196. doi: 10.1016/j.clnesp.2024.03.019

University of Aberdeen. Could fish oil be key in protecting the elderly against muscle deterioration?05 September 2012. Last viewed: 04/28/25