The eight-week study found that observed body composition and muscle function improvements may be due to the well-established benefits of resistance training and adequate protein, rather than omega-3 supplementation.
The researchers in Iran and France suggested omega-3’s muscle benefits may require higher doses or longer interventions.
“Short-term omega-3 supplementation selectively modulated biochemical markers but did not provide additional improvements in SMM [skeletal muscle mass], performance, or clinical safety markers, suggesting that its benefits may be limited without longer-term or higher-dose interventions,” they wrote in Nutrients.
Hormonal fluctuations, menopause, and dietary and lifestyle factors can contribute to loss of SMM as women age, putting them at risk of obesity, sarcopenia, and osteoporosis.
Evidence suggests that higher-protein diets may support muscle synthesis and adaptive responses to resistance training, leading to greater improvements in body composition than standard protein intake.
Omega-3 fatty acids may benefit cardiometabolic health, cognition, and skeletal muscle preservation. The study noted that previous research suggests that omega-3 supplementation at doses of above 2g daily for at least six months may preserve muscle, strength, and performance.
Emerging evidence also suggests that “shorter-term omega-3 supplementation may still modulate muscle anabolic and catabolic signaling pathways, thereby influencing early metabolic adaptations, the researchers wrote.
Study details
A total of 44 overweight women aged 40 to 53 completed the eight-week study. They had previously engaged in less than 1 hour of structured exercise per week and had a habitual daily protein intake below the study amount.
They were randomly assigned to consume either omega-3 supplementation (1180 mg fish oil plus 12 IU vitamin E) and a high-protein diet (1.6 g per kg bodyweight daily), or a placebo and a high-protein diet, both combined with full-body resistance training at 50–80% of 1-RM, three times per week. There was also a non-training control group.
The researchers assessed body composition, muscular performance, and metabolism before and after the intervention.
Compared to the control group, “both intervention groups demonstrated significant improvements in anthropometric variables, including body mass, BFP [body fat percentage], and SMM,” the researchers wrote, noting that the BFP was comparable in both intervention groups.
Both training groups showed gains in muscular strength, endurance, and power, exhibiting elevations in the follistatin-to-myostatin ratio, a marker for muscle growth, particularly in the omega group. However, this was assessed in serum rather than muscle, which the researchers noted may not reflect muscle-specific regulation.
“Contrary to our primary hypothesis, omega-3 supplementation did not confer additional increases in SMM or performance beyond RT combined with a high-protein diet over the eight-week intervention,” the researchers wrote, suggesting that the short-term increases in SMM likely reflect the well-established effects of RT with adequate protein intake.
They called for further investigations over longer periods or at higher doses to fully elucidate the functional effects of omega-3 in similar scenarios.
Source: Nutrients; doi: 10.3390/nu18040611; “Effects of 8 Weeks of Resistance Training Combined with a High-Protein Diet and Omega-3 Supplementation on Body Composition, Muscular Performance, and Muscle-Related Biomarkers in Overweight Women.” Authors: B. Radfar et al.
