'Vegetarian gene' puts Indians at cancer risk

Could there be a vegetarian gene? A new study has revealed that eating green could be in our genes.

The Cornell University researchers have found evidence of a genetic variation, called an allele, which has evolved in populations that have historically favoured vegetarian diets, such as in India, Africa and parts of East Asia.

They also discovered a different version of this gene adapted to a marine diet discovered among the Inuit in Greenland, who mainly consume seafood.

The vegetarian allele evolved in populations that have eaten a plant-based diet over hundreds of generations. The adaptation allows these people to efficiently process omega-3 and omega-6 fatty acids and convert them into compounds essential for early brain development and if they stray from a balanced omega-6 to omega-3 diet, it may make people more susceptible to inflammation, and by association, increased risk of heart disease and colon cancer.

In Inuit populations of Greenland, the researchers uncovered that a previously identified adaptation is opposite to the one found in long-standing vegetarian populations: While the vegetarian allele has an insertion of 22 bases (a base is a building block of DNA) within the gene, this insertion was found to be deleted in the seafood allele.

"The opposite allele is likely driving adaptation in Inuit," said co-lead author Kaixiong Ye, adding that the study is the first to connect an insertion allele with vegetarian diets and the deletion allele with a marine diet.

The team analyzed frequencies of the vegetarian allele in 234 primarily vegetarian Indians and 311 U.S. individuals and found the vegetarian allele in 68 percent of the Indians and in just 18 percent of Americans. Analysis using data from the 1,000 Genomes Project similarly found the vegetarian allele in 70 percent of South Asians, 53 percent of Africans, 29 percent of East Asians and 17 percent of Europeans.

Ye noted that they can use this genomic information to try to tailor our diet so it is matched to our genome, which is called personalized nutrition.

The researchers are not sure yet when the adaptation first occurred, as analyses of chimpanzee or orangutan genomes did not uncover the vegetarian allele. But there is evidence for the allele in early hominid Neanderthal and Denisovan genomes.

The study appears in the journal Molecular Biology and Evolution.