Monday, October 14, 2013

Sesame Powered High Omega-6 Diet Boosts Endurance Performance in Rodents - High Omega-3 Diet Sucks: Intra-Muscular Lipid Ratios Determine Exercise Performance

At least in rodents omega-6s appear to make abetter match with exercise than in human beings.
I actually referenced this study several times in the past. It came up in a Facebook conversation I had with Roy Nelson who pointed me to a press release telling me that (I quote) "Certain Fat Could Help Humans Lose Weight". Interestingly, the "certain fat" in this particular study is (brace yourselves) linolic acid, better known as "omega-6" (obviously a misnomer, since omega-6 is actually referring to a whole class of fatty acids).

In view of the fact that the corresponding study in which Rogowski et al. observed a significant correlation between the omega-6 fatty acid content in the muscle and mitochondrial uncoupling and fat oxidation. The problem with the study is however that it was conducted not just with mice, but with genetically modified mice.

The results of the said study by Rogoswki, Patin et al. may thus form the basis for further investigations, but should not be taken as "hard evidence" that a high intake of omega-6 fatty acids will have similar effects. The accumulation of linolic acid in the mouse muscles was after all a result of the genetic modification and not the consequence of high n-6 chow.

So what's the effect of dietary linolic acid, then?

Unlike Rogowski et al., Kerry J. Ayre and A.J. Hulbert from the University of Wollongong did not just use normal male Wistar rats as their test objects, they also did what the scientists from Texas Tech didn't do: They supplied their rodents with diets with different fatty acid profiles.
Table 1: If you have ever wondered about the "evolution" of the omega-3 vs. omega-6 ratio in our (=the human) diet, I suggest you take a closer look at the table to the right. According to this overview from a 2004 paper by Artemsis Simopoulus in Food Reviews International. As you will see, it has more than just reversed ever since the paleolithic era.
All diets contained the exact same macronutrient composition with 22%, 56% and 22% of the total energy being derived from fat, carbohydrates, and protein, respectively. The amount of essential fatty acids and their ratios in the 22% fat content of the diet did however differ significantly:
  • Irrespective of the fact that it sucks for rodent endurance, coconut oil could help you approach a flat tummy like the one above| learn more
    Coconut diet: Designed as (almost) "essentially fatty acid free", the coconut oil based diet had a saturated fatty acid / mono-unsaturated fatty acid / N-6 / N-3 ratio of 95:4:1:0
  • High N-6: Being based on sesame oil, the high N-6 diet had a SFA / MUFA / N-6 / N-3 ratio of 16:30:50:4 that translates to an N-3:N-6 Ratio of 0.08 (1:12.5); now that sounds crazily low, but the average Westerner consumes a diet with a N-3:N-6 ratio of 0.0625 (1:16; cf. Simpopoulos. 2004) in other words - that was not even "as bad" (?) as the Western diet
  • High N-3: By adding both sesame and a commercially available omega-3 supplement to the diet, the scientists hit a 21:25:35:16 ratio for SFA / MUFA / N-6 / N-3 - that's still far from "N-3 exclusive" but much more like what current expert advice tells us we should strive for, i.e. 1g of omega-3 for every 2g of omega-6
If we go by the contemporarily popular dietary paradigms, it should be obvious that the health of the rodents in the N-6 diet will take a beating. Against that background it is all the more surprising that it were the rodents in the high N-6 group that outdistanced their hairy competition in an endurance test at the end of the 9 week study period.
Figure 1: Fatty acid composition of the diets and corresponding endurance performance of male Wistar rats after 9-weeks on coconut, high n-6 and high n-3 diet (Ayre. 1997)
What's more, it's not as if the omega-6 mice had simply been running slower and were thus able to run for a longer time, they did also have higher workloads (=product of body mass, distance traveled, and percentage grade of the incline).

"So where is the connection to the new study from Texas Tech, then?"

If we look back at the initially mentioned results from the Texas Tech study, it appears logical to assume that the beneficial effects on the endurance capacity could be another downstream effects of an increased ability to oxidize dietary fats (which is basically what the Rogowski, Paton et al. argued). Compared to the minimal amount of blood glucose and the highly limited glycogen stores in the muscle and liver, the fat stores of mice (and man) do after all hold an almost inexhaustible amount of energy - they just have to be accessed.
Figure 2: Skeletal muscle fatty acid composition after 9 weeks (Ayre. 1997)
As you can see, in figure 2 the fatty acid composition of the skeletal muscle of the rodents in the Ayre study did reflect the fatty acid composition of the diets (remember: the changes in the Rogowski study occured on the same chow, simply due to a genetic mutation) and the significantly increased omega-6 content in the N-6 group mirrors the effect Rogowski et al. observed in response to their neat GMO tricks. It does therefore appear logical to assume that the rodents in the Ayre study experienced a similar upregulation of PPAR-delta (unfortunately back in the day scientists did not measure that). The latter would increase the oxidation of fatty acid and thus the energy availability during aerobic activity.

"Making the Right Fish Choices" is important for your healths, so I suggest you learn how in the same-titled SuppVersity article.
What should not go unmentioned is that the performance discrepancies were very long-lived. Even after 5 weeks on a regular diet, the rodents in the N-6 diet easily outperformed their coconut and omega-3 competition - probably because it takes months (in rodents and years in men) to restore a "normal" muscular fatty acid profile. Now this is an interesting thought, because it will eventually lead us to the hypothesis that the huge benefits we are currently seeing (at least in some individuals) from the consumption of supplemental omega-3 fatty acids would be a direct result of the their effect on a cellular fatty acid ratio that has been messed up over years!

In view of the profundity of the omega-6 overshoot in the SAD diet and considering the fact that many of us have been consuming diets containing 15x more omega-6 fatty acids than omega-3s for decades, this does not appear unlikely. From a scientific perspective it would yet reaffirm that the "optimal n3:n:6 ratio" for someone with a well-balanced cellular level of the latter could be very different from the 1:1 optimum some experts currently recommend as target in the battle against diabesity - right?
Swine study says 1:5 ratio of N3:N6 or higher = optimal health | more
Let's ground ourselves: Don't take this post as an incentive to guzzle vegetable oil all day.

As a strength athlete you may actually harm yourself as it appears that the high omega-6 intake favors the oxidative over the glycolytic pathway. As an endurance athlete, however you may reconsider how important it really is for you to avoid all omega-6 fatty acids as a plague.

On a more general note, it may in fact be worth to take another look at "optimal ratios". While some of the effects of the polyunsaturated fatty acids are in fact acute, their major effects appear to be brought about by their accumulation in our bodies.

The "optimal intake" will thus necessarily depend on the status quo, i.e. the current tissue level of n-3 and n-6 fatty acids and their respective ratios. Against that background we should not be surprised that you can counter the negative effects of an imbalanced diet by administering another imbalanced diet. In our case this is a correction of a profound omega-6 overshoot that can be achieved by increasing our consumption of omega-3 rich foods and limiting our use of omega-6 laden vegetable oils and the products of which the "food" industry tells us they were good for us, because they contain only healthy vegetable oils... this is a practice I have recommended in the past and something I still recommend today.

What I would hope we could agree on, though is the idea that the study at hand, despite being conducted in rodents should remind us that simply switching from one scapegoat to another did not help us, when that scapegoat was saturated fat. Do you really believe the outcomes will be better, when we simply glue the "avoid like a plague" sticker to the omega-6s? Yes? Well, I guess the first thing you should do then, is take your beloved extra-virgin olive oil and pour it away! Why? Well, 10% omega-6 and basically no omega-3 - that's a no go ;-)
  • Ayre KJ, Hulbert AJ. Dietary fatty acid profile affects endurance in rats. Lipids. 1997 Dec;32(12):1265-70. 
  • Pella D, Dubnov G, Singh RB, Sharma R, Berry EM, Manor O. Effects of an Indo-Mediterranean diet on the omega-6/omega-3 ratio in patients at high risk of coronary artery disease: the Indian paradox. World Rev Nutr Diet. 2003;92:74-80.
  • Rogowski MP, Flowers MT, Stamatikos AD, Ntambi JM, Paton CM. SCD1 activity in muscle increases triglyceride PUFA content, exercise capacity, and PPARĪ“ expression in mice. J Lipid Res. 2013 Oct;54(10):2636-46.
  • Simopoulos, AP. Omega-6/omega-3 essential fatty acid ratio and chronic diseases. Food Reviews International. 2004; 20(1).