Effects of exercise training on fatty acid composition under dietary intervention with deficient and adequate levels of n-3 polyunsaturated fatty acids in mice

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), particularly eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), have been widely recognized for their health benefits. While both dietary intake of n-3 PUFAs and exercise training independently influence fatty acid metabolism, their combined effects on tissue-specific fatty acid composition remain unclear. In the present study, we investigated the fatty acid profiles of total lipids in serum, liver, gastrocnemius muscle, heart, kidney and brain to comprehensively evaluate the effects of exercise training under dietary different n-3 PUFAs levels. Results revealed that dietary supplementation with n-3 PUFAs significantly increased EPA and DHA levels and decreased Σn-6/Σn-3 PUFAs ratios in serum, liver, muscle, heart, and kidney. Notably, the exercise-induced changes in n-3 PUFAs were modulated by both dietary n-3 PUFAs levels and exercise duration. Under n-3 PUFAs adequate conditions, short-term exercise preferentially mobilized n-3 PUFAs from peripheral tissues, while long-term exercise promoted DHA redistribution from the circulation to metabolically active tissues. Under n-3 PUFAs deficient conditions, prolonged exercise accelerated tissue n-3 PUFAs depletion, highlighting enhanced utilization and redistribution when dietary supplementation was limited. Notably, exercise training also reduced tissue levels of pro-inflammatory C20:4 and monounsaturated fatty acid C18:1, especially in liver and serum. In contrast, fatty acid composition in the brain remained largely unchanged across interventions. These results highlighted the tissue specific modulation of fatty acid profiles through the interaction of diet and physical activity. This study provided a comprehensive investigation about the changes of fatty acid composition based on exercise training and dietary n-3 PUFAs level in vivo, offering a scientific basis for exercise physiology and targeted nutritional supplementation.