Monday, October 5, 2009

Can you zone out of the Zone, part 2

The ratio of N-6 to N-3 fats has far reaching metabolic effects on the body. While the amount of N-3 has reduced due to eating less fresh seafood/fish, the amount of N-6 has increased dramatically due to the push for "heart-healthy" vegetable oils to be used for cooking, in margarine, dressing oils and in most packaged foods. This ratio has traditionally been around 1:1 - 2:1 (6:3) but now ranges any where from 10:1 - 30:1 depending where you look. They can affect many aspects of our physiology but most are ultimately related to their effect on Eicosanoid production.

The intricate details of eicosanoid production and use aren’t perfectly understood, and Sears (of the Zone) version is slightly different to others I have seen. Basically: When N-6 and N-3 fats are digested and absorbed, they are metabolised into GLA for N-6 and EPA for N-3, then stored in the membranes of all cells (the process is a little more complicated but that’s the gist of it anyway). The proportion in the membrane is roughly equal to the proportion in long term diet. So when the body needs eicosanoids it liberates the activated acids and metabolises them further, but the enzymes used do not distinguish between N-6 and N-3, so proportion in the cell will determine which eicosanoids are made. N-3 can offset production of GLA into arachidonic acid (AA) by competing for the same enzyme system. Eicosanoid family's include Prosataglandins (PG), Prostcyclins (PGI), Thromboxanes (TxA), and Leukotrienes (LT). Some of these are made using the cyclooxygenase (COX) metabolic pathway. These have varying actions and interactions, some of which are directly opposing and/or suppressing. AA eicosanoids such as TxA-2 and PGE-2 are predominantly 'bad', promoting vasodilation, platelet aggregation, inflammation, cellular proliferation and immune depressing. 'Good' eicosanoids are the opposite, while a lot of those from EPA (N-3 derived) are essentially neutral or involved in long term healing.

So balance of these two Essential Fatty Acids (EFA's) is, well, essential. N-3 supplementation through fish oil can help balance this out. Problem is that it seems that at a certain level of intake, tissue 'saturation' of N-6 can occur, meaning that once past a certain threshold of calories as N-6, intake over and above this does little to affect cell membrane levels. This means that as AA in the cell increases, EPA and DHA decrease proportionally. Increasing N-3 can help but it would seem that reducing N-6 to below 4% calories is more important (ref here).

How does all this relate back to the zone. Well as usual insulin and glucagon have a big influence over the enzyme activity and metabolism of ingested EFA's. Excess insulin stimulates the enzyme systems responsible for the metabolism of DGLA and AA into 'bad' eicosanoids. How can we control insulin? As we have seen, through a low carb diet.

Inflammation can also be controlled easily with paleo. Reducing grains, starch and simple sugars as all are inflammatory, as is the elevated insulin they stimulate. High fructose corn syrup should also be avoided at all costs. Promoting good gut flora through Probiotics and prebiotics supplements when necessary, such as during illness, antibiotic use, excessive toxic load (drugs, alcohol, environmental toxins). Supplements of Vit D, C, Fish oil, K or whichever combination, as well as vegetable antioxidants (from vegetables, der). Reducing total N-6 intake is very important as found above, but this should come naturally on a whole-foods paleo diet. Curcumin, the active constituent in Tumeric (a root herb) can inhibit the COX pathway to reduce inflammation, especially when taken with black pepper to protect its activity during digestion. Saturated fat is also recommended against by the zone diet due to claims of inflammation, but this has not been exclusively proven, especially by the method mentioned by the zone and Sears, claiming toll-like receptors are stimulated by sat' fat, causing inflammation. (ref here, here and here)

Lastly the meal frequency recommended to keep you in the zone is questionable. Claiming that the hormonal and eicosanoid balancing effects are where of after 4-6 hours and you shouldn’t space out meals further than 5 hours, to keep you in the zone. This is very contrary to evidence of traditional cultures fasting for 12-24 hours at a time throughout our evolution, and the physiology of the body shows that we can function perfectly when fasted as we are using fat for fuel and obviously insulin will be low at this time, so I don’t see that as an issue. Snacking all day just constantly stimulates insulin keeping it at a raised level as our body is constantly in digestion mode, even if the meals are zone balanced, that’s still more insulin than not eating at all (especially when as mentioned even 40% is to many carbs for many people and will stimulate even more insulin).

In the end the Zone diet is a great starter for those wanting to square away their diet and improve performance. The benefits of which I don’t believe are restricted to the zone however and can be easily done on a diet from Zone proportions of 40% carb if you are training very high volume/intensity (above and beyond Crossfit 3 - 1 cycle), down to very low carb of 50g/day (this will all depend on your goals and training). Reducing or eliminating vegetable oil from all sources and supp'ing N-3 is vital, in addition to adapting to a reduced carb diet to ensure all metabolic processes are running smoothly. This is where Robb Wolf's motto of quality over quantity wins every time: The benefits of weighing and measuring, blocks, snacking and staying in the zone can be accomplished with quality paleo foods with no measuring. The physiology discussed on the zone lectures with Dr. Sears (in the CF journal recently) is all true, but not just applicable to a diet that follows a 40/30/30 split and good N-6:3 balance. To many cultures follow drastically different (yet all paleo) diets with no sign of the 'silent killer' inflammation or heart disease or diabetes etc... As with any diet, care must be taken to ensure adequate intake of all nutrients, especially when on very low carb, but the health benefits are obvious, with the mountain anecdotal evidence of paleo showing up around Crossfit and all over the net.


Brett_M/30/181cm/84kg said...

Dude I could read your posts all day.

They re inspire me to address flaws in my eating plan.

Thanks :)

Steve_M/26/171cm/72kg said...

cheers mate

doing these posts helps clarify points i've been thinking about and gets them down on paper(?), and makes me look further to back my own argument.

I'll do a post soon on my average diet if that helps..