Dukan Diet

Here is a review:

It is hard to sort out the inflammatory effects of short/long-chain omega-6 and omega-3 fatty acids. Vegetable antioxidants make the picture even worse. The absolute, as well as relative amounts, of the various types of fatty acids make a difference. It also now appears that oxidation prior and during digestion may be important to the impact of polyunsaturated fatty acids (PUFAs). The source (perhaps even the meal composition) of the PUFAs was as important as omega-3 versus omega-6, for common, short chain PUFAs.

In some studies, omega-3 PUFAs, such as the short-chain alpha linolenic acid (ALA) common in flax seed or the long-chain fish oil FUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), reduced cancer in human and mice. Earlier work in cell cultures showed that all of PUFAs suppressed the growth of cancer cells.

A large French study (reference below) began in 1993. Approximately 100,000 women between the ages of 40 and 65 volunteered to provide dietary and breast malignancy information and ca. 75,000 qualified for the study (the French component of EPIC, European Investigation of Cancer and Nutrition) . The dietary data provided information on the fatty acid composition of meals and revealed who was eating vegetable antioxidants and vitamins.

Major findings:

• Neither omega-6 nor omega-3 fatty acids were related directly to breast cancer risk.
• Long chain omega-3 fatty acids (EPA and DHA) reduced breast cancer in the group of women with the highest consumption of omega-6 PUFAs.
• High LA or ALA consumption in the form of vegetable oils or vegetables reduced cancer incidence.
• High LA or ALA consumption in the form of processed foods or nuts was associated with a higher incidence of breast cancer.
• Longer chain PUFAs were not associated with increased risk, regardless of source.

What does this mean?

• The source of the PUFA is of paramount importance. This study may apply more specifically to cancers and less to other inflammation-based degenerative diseases. The general anti-inflammatory diet may need refinement. I would suggest the following additions:
• Retain the preference for the more omega-3 friendly olive oil or perhaps flax oil versus the omega-6 rich vegetable oils (corn, soy, safflower), but focus on freshness and do not heat these oils.
• The data seem to be in favor of saturated fats for cooking. That means a shift to coconut oil.
• Vegetable antioxidants may be most important in the gut during digestion. Do these antioxidants even enter the blood stream? Certainly some alkaloids get to the brain, but much of the impact of the less mobile, large molecules may be restricted to the gut.
• An extension of this discussion may be to encourage eating more leafy vegetables with meat. That may be the paleo-diet connection.

reference:
Thiébaut AC, Chajès V, Gerber M, Boutron-Ruault MC, Joulin V, Lenoir G, Berrino F, Riboli E, Bénichou J, Clavel-Chapelon F. 2009. Dietary intakes of omega-6 and omega-3 polyunsaturated fatty acids and the risk of breast cancer. Int J Cancer. Feb 15;124(4):924-31.

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 whats 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 didnt do: They supplied their rodents with diets with different fatty acid profiles.
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 - thats 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)

Whats more, its 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?
References:

• 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 PPARδ 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).