The least stable n-3 fats which accumulate with age and gradually reduce energy production also have their short term effects on endurance. Endurance was much lower in rats fed a high n-3 fat diet, and the effect persisted even after 6 weeks on a standard diet (Ayre and Hulbert, 1997). -Ray Peat, PhD
Lipids. 1997 Dec;32(12):1265-70.
Dietary fatty acid profile affects endurance in rats.
Ayre KJ, Hulbert AJ.
Typically athletes are advised to increase their consumption of carbohydrates 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 composition of the polyunsaturated fat component should not be ignored. The aim of this study was to manipulate the dietary fatty acid profile in a high-carbohydrate diet in order to investigate the effect of dietary polyunsaturates on submaximal endurance performance in rats. Rats were fed one of three isoenergetic diets containing 22 energy percentage (E%) fat for 9 wk. The diets comprised an essential fatty acid-deficient 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, High 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 then at 9 wk, it was again significantly 50% lower in the High n-3 group than the High n-6 group (P < 0.005). Although n-3 fats are considered beneficial for cardiovascular health, they appear to reduce endurance times, and their side effects need to be further investigated.
Analogous, but less extreme effects are seen even in salmon, which showed increased oxidative stress on a high n-3 diet (DHA and EPA), and lower mitochondrial cytochrome oxidase activity (Kjaer, et al., 2008). -Ray Peat, PhD
Lipids. 2008 Sep;43(9):813-27. Epub 2008 Jul 10.
Dietary n-3 HUFA affects mitochondrial fatty acid beta-oxidation capacity and susceptibility to oxidative stress in Atlantic salmon.
Kjaer MA, Todorcević M, Torstensen BE, Vegusdal A, Ruyter B.
Atlantic salmon (Salmo salar) (90 g) were fed four different diets for 21 weeks (final weight 344 g). The levels of n-3 highly unsaturated fatty acids (HUFA) ranged from 11% of the total fatty acids (FA) in the low n-3 diet to 21% in the intermediate n-3 diet, to 55 and 58% in the high n-3 diets. The high n-3 diets were enriched with either docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA). Increasing dietary levels of n-3 HUFA led to increasing percentages (from 31 to 52%) of these FA in liver lipids. The group fed the highest level of DHA had higher expressions of peroxisome proliferator-activated receptor (PPAR) beta and the FA beta-oxidation genes acyl-CoA oxidase (ACO) and carnitine palmitoyltransferase (CPT)-II, compared to the low n-3 groups. The high n-3 groups had reduced activity of mitochondrial cytochrome c oxidase and beta-oxidation capacity, together with increased activities of superoxide dismutase (SOD) and caspase-3 activities. In the group fed the highest level of n-3 HUFA, decreased percentages of major phospholipids (PL) in the mitochondrial and microsomal membranes of the liver were also apparent. The percentage of mitochondrial cardiolipin (Ptd(2)Gro) was 3.1 in the highest n-3 group compared to 6.6 in the intermediate group. These data clearly show an increased incidence of oxidative stress in the liver of fish fed the high n-3 diets.
