A study by Cornell University researchers published in Molecular Biology and Evolution shows that a genetic variation—called an allele—has evolved in populations that have historically favored 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 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.
The researchers analyzed frequencies of the vegetarian allele in 234 primarily vegetarian Indians and 311 U.S. individuals and found the vegetarian allele in 68% of the Indians and in just 18% of Americans. Analysis using data from the 1,000 Genomes Project similarly found the vegetarian allele in 70% of South Asians, 53% of Africans, 29% of East Asians, and 17% of Europeans.
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 Kaixiong Ye, co-lead author of the paper and postdoctoral researcher in Cornell’s biological statistics and computational biology department. “Our study is the first to connect an insertion allele with vegetarian diets, and the deletion allele with a marine diet.”
Previous work by co-senior author Tom Brenna, professor of human nutrition and chemistry at Cornell University, showed that the allele insertion can regulate the expression of FADS1 and FADS2— enzymes that are essential for converting omega-3 and omega-6 fatty acids into downstream products needed for brain development and controlling inflammation—and hypothesized it could be an adaptation in vegetarian populations.
“One implication from our study is that we can use this genomic information to try to tailor our diet so it is matched to our genome, which is called personalized nutrition,” said Ye.
