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Carb tolerance related to geography?

I’ve long suspected that how we respond to food is influenced by where we come from. It just made sense. Human evolution is just too smart to not have adapted to the foods around us. I’ve also often thought that for those of us living in countries like Canada and the USA, that we can’t just take for granted that the food here is what we are meant to eat. Many of us are first or second generation in this country, which, following my thought process, suggest that we may be displaced nutritionally. And having seen different people respond very differently to the same food, it only made sense to me.

Which is why this blog post by a nutritionist at Precision Nutrition caught my attention. It reviews recent research about genetic variations as they relate to carb-tolerance, and how those variations seem to have geographic ties. Here’s the full article for those like me who find this stuff fascinating, and here’s my super-brief summary version:

  • Research has recently shown that ability to make amylase correlates with obesity
  • Amylase is made by the AMY1 gene
  • It turns out we don’t all have the same number of copies of genes; and in fact we can have from 2 to 16 copies of AMY1.
  • Those with more copies of AMY1 can breakdown carbs more effectively than those with fewer.
  • “People living in historically agricultural societies like Japan had, on average, seven copies of AMY1, while people near the arctic circle in places like Yakut, Russia had, on average, four copies of AMY1.”
  • “If you have more than nine copies of AMY1 then you are eight times less likely to be obese compared to someone who has fewer than four copies of AMY1.”
  • The article points out that the variance above was based on a small range of BMI (25-27kg/m2), so care must be taken in interpreting the meaning.

Fascinating stuff! It’s very clear that there is much more to learn on this topic, but still – interesting!

I guess because this is about carbs, but this topic makes me think of the new research Gary Taubes is doing. In principle, it’s an impressive undertaking, as they are looking at individuals in isolation where they can actually monitor response to food as opposed to counting on the ever-flawed self-reporting. What concerns me is that all of their participants are overweight or obese. If the research above holds true, then those who are overweight or obese have a different carb-tolerance than those who are not. So if Taubes’ research does show that a low-carb diet is better for their participants, is it applicable to the entire population? Or just to those who are already overweight?

Clearly the result of that study is still going to be interesting and important; but it probably shouldn’t be taken as being “the best diet”.

All that to say – there is interesting research going on in the world of nutrition!

Elsbeth Vaino, B.Sc., CSCS, is a personal trainer in Ottawa who finds nutrition and exercise research to be intriguing.

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