The main aim was to investigate the association of n-3 fatty acid intake and the n-6/n-3 fatty acid intake ratio with muscle mass and strength in older adults. This study included 61,381 individuals (28,187 men and 33,194 women) aged ≥60 years.

Grip strength and muscle mass index were assessed and n-3 and n-6 fatty acid intake were determined. Regression models adjusted for age, deprivation index, ethnicity, month of assessment, total energy intake, multimorbidity, lifestyle factors and physical activity.

A sensitivity analysis was conducted in participants aged ≥65 years and in people with sarcopenia. Data are presented as trend for quintiles from fully adjusted models.

Higher n-3 fatty acid intake was associated with a higher grip strength in both men (0.114 kg; 95% CI: 0.02 to 0.21) and women (0.115 kg; 95% CI: 0.05 to 0.18). Similar results were reported for grip strength index, with no associations observed for muscle mass index.

No associations were seen in people ≥65 years. In people with sarcopenia no associations of n-3 fatty acid intake with grip strength or grip strength index were seen, but a positive association with muscle mass index was noted in men (0.197 kg/m²; 95% CI: 0.05 to 0.33).

The n-6/n-3 fatty acid intake ratio was associated with grip strength in women (0.081 kg; 95% CI: -0.16 to 0.000) and with muscle mass index in men (-0.016 kg/m²; 95% CI: -0.02 to 0.00), no other associations were observed. No associations were seen in people with sarcopenia or people ≥65 years.

Higher n-3 fatty acid intake, with no consistent association with the n-6/n-3 fatty acid intake, was modestly associated with grip strength, with effects varying by sex and age, suggesting limited benefit for sarcopenia prevention at typical intake levels in older adults.