DIETARY FATTY-ACID PROFILE AFFECTS ENDURANCE IN RATS

Typically, athletes are advised to increase their consumption of carbo hydrates for energy and, along with the general population, to reduce consumption of saturated fats. It is now recognized that fats are not identical in their influence on metabolism, and we argue that the comp osition of the polyunsaturated fat component should not be ignored. Th e aim of this study was to manipulate the dietary fatty acid profile i n a high-carbohydrate diet in order to investigate the effect of dieta ry polyunsaturates on submaximal endurance performance in rats. Rats w ere fed one of three isoenergetic diets containing 22 energy percentag e (E%) fat for 9 wk. The diets comprised an essential fatty acid-defic ient diet (containing mainly saturated fatty acids); a diet high in n- 6 fatty acids, High n-6; and a diet enriched with n-3 fatty acids, Hig h n-3. Submaximal endurance in rats fed the High n-3 diet was 44% less than in rats fed the High n-6 diet (P< 0.02). All rats were then fed a standard commercial laboratory diet for a 6-wk recovery period, and their performances were reevaluated. Although endurance in all groups was lower than at 9 wk, it was again significantly 50% lower in the Hi gh n-3 group than the High n-6 group (P < 0.005). Although n-3 fats ar e considered beneficial for cardiovascular health, they appear to redu ce endurance times, and their side effects need to be further investig ated.