Vegetarian diet may have shaped genetics

Posted on Wed, 18 May 16

It is not only "you are what you eat,” but “you are what your ancestors ate” according to a new study that suggests traditional vegetarian diets may have permanently shaped human genome.

Traditional human diets vary tremendously across geography and culture, with some practically carnivores (such near the polar circle), while others are vegetarian (nearer the equator).

It is possible that traditional dietary patterns have shaped the human genome over time and, if so, such changes would have important implications for personalized nutrition.

Recently a research group tested their theory that an adaptive genetic polymorphism that improves essential fatty acid metabolism would confer an advantage for people who consume a traditional vegetarian or vegan diet.

Metabolism of essential fatty acids from plant-sources requires conversion to important downstream metabolites, especially arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and is generally poor, so genetic variations that result in better metabolism would likely confer health benefits and be genetically selected for over generations.

By comparing genetic data from a population with a long history of vegetarianism (from Pune, India) to a traditional meat-eating American population they discovered that there is a higher frequency of particular mutations that improve essential fatty acid metabolism (in the FADS1 and FADS2 genes) (1). 

This discovery may have important implications for personalized medicine as not only would it mean some people are perhaps better suited to a traditional vegetarian diet, but these gene variants could also be maladaptive with overexposure to fats and oils typical of a western industrialized diet. It is possible that in the context of a western diet increased metabolism conferred by these genes would increase production of pro-inflammatory metabolites linked to the development of heart disease and cancer. Further, individuals who do not carry the gene variants may stand to benefit more from dietary EPA and DHA.

In a similar way, populations that are predominately carnivores such as the Greenland Inuit may be uniquely adapted to their traditional diet (2). So it seems the optimal diet for you may be determined by your ancestry and encoded in your genes.

References: 

1. Kothapalli KS, et al. Positive Selection on a Regulatory Insertion-Deletion Polymorphism in FADS2 Influences Apparent Endogenous Synthesis of Arachidonic Acid. Mol Biol Evol. 2016 Mar 29. pii: msw049. [Epub ahead of print] 
2. Fumagalli M, et al. Greenlandic Inuit show genetic signatures of diet and climate adaptation. Science. 2015 Sep 18;349(6254):1343-7.
3. Caspermeyer J. Are We What We Eat? Evidence of a Vegetarian Diet Permanently Shaping the Human Genome to Change Individual Risk of Cancer and Heart Disease. Mol Biol Evol. 2016 May 2. pii: msw076. [Epub ahead of print]