Impact of dietary essential fatty acids on phospholipid composition and mitochondrial function in aged mares

Advancing age is associated with a decline in fertility and functional capacity, which may result in part from suboptimal nutrition and impaired mitochondrial function. Dietary essential polyunsaturated fatty acids (PUFA) are broadly recommended to mitigate weight loss and reduce risk of chronic disease in aged populations, but their effects on mitochondrial function are less clear. The present study investigated the impacts of dietary supplementation with essential omega-3 PUFA (flaxseed oil; N3) or omega-6 PUFA (corn oil, N6) on blood, muscle and follicular cell fatty acid composition and mitochondrial function in aged light-horse mares (23.2 ± 1.1 year), which are excellent models of human reproductive aging and a focus of dietary interventions in the equine industry. Diets were fed for 6 weeks before adding a supplemental supportive nutrient formulation (DS) designed to optimize equine metabolic health for another 6 weeks. Results demonstrate tissue-specific effects of the dietary oils on mitochondrial function, most notably a decrease in oxidative capacity of platelets and muscle, and greater release of reactive oxygen species (ROS) from granulosa cells and muscle, with no significant difference in effects between N3 and N6 diets. Addition of the DS improved oxidative phosphorylation efficiency and tended to reduce ROS release across all cell types, and increased basal oocyte oxygen consumption. Taken together, these results provide novel insight to the diverse impacts of dietary PUFA intake on equine mitochondrial function, and suggest that supportive nutrients may be required to prevent negative health effects of dietary oil supplementation in aged mares.