|Image 1: Unexpectedly ergogenic - Carthamus tinctorius L., better known as "safflower", a highly branched, herbaceous, thistle-like annual.|
|Video 1: Not the swimming test performed in the study, but maybe an explanation why mouse-oil might be good for fish, but not vice versa - or have you ever seen a mouse eating a fish?|
|Figure 1: Effect of 12 weeks on diets with 6% lard, fish oil and safflower oil on swimming endurance of aged mice (data calculated based on Zhang. 2011).|
|Figure 2: Effect of 12 weeks on diets with 6% lard, fish oil and safflower oil on lactate levels pre and post endurance exercise in aged mice (data calculated based on Zhang. 2011).|
These results imply that the improved endurance associated with dietary safflower oil may be due, at least in part, to glycogen sparing. The working skeletal muscle is not only the major site of lactate production but is also important for utilization of lactate, which is mainly removed by oxidation. The decreased accumulation of lactate observed in aged mice fed safflower oil could be due to increased lactate oxidation and subsequent utilization as an additional energy source during swimming.Yet the effect on accumulation or utilization of lactate was not the only difference that may have contributed to the increase in swimming performance that was observed in the safflower oil group. As the researchers point out,
the significant increase in muscle and liver CPT activities and decrease in plasma NEFA levels observed following exhaustive swimming in mice fed safflower oil implies an upregulation of fatty acid metabolism in these mice.The absence of these effect in the lard or fish oil fed animals suggest that "the safflower oil group may have increased fatty acid utilization for energy than the other diet groups". In that, it is particularly noteworthy that we are talking about a localized increase in CPT activity and consequent fatty acid oxidation in muscle tissue. The increased liver CPT in the fish oil group, on the other hand could have contributed to an overall negative effect of fish oil consumption on endurance performance that would have been corroborated by the established suppressive effect of N3PUFAs on fatty acid synthesis (Kim. 1999; Nakatani. 2004) and lipid oxidation (Rustan. 1993), against the backdrop of which less fatty acids became available for and subsequently oxidized in skeletal muscle.
|Image 2: Biological activities of IL-6 (illustration by Prof. Dr. Heinrich)|
So, what would be the overall lesson, we can learn from the results of this study? Fish oil is poison, safflower oil liquid gold? Probably not. Yet, while it may still be questionable in how far the mouse metabolism is a good model for the human one, the inhibition of fatty acid synthesis and the increased fatty acid oxidation observed in mice as a consequence of fish oil feeding is present in humans, as well. Moreover, I assume you would agree that not everything that would be beneficial for the average sedentary borderline to morbidly obese inhabitant of the Western Hemisphere, is equally beneficial for performance-oriented athletes - or would you suggest 200 meter sprinters start swallowing statins and blood pressure medications? So, wouldn't it be remotely possible, then that a physical culturist (as I hope you would consider yourself to be one) would be much better off with a reasonable amount of those "nasty" n6-PUFAs in his/her diet to keep the fire in the mitochondrial furnace of his/her muscles in full blast? If you want to, ask your guru about it ;-)