Vegetarian diet makes Indians more prone to colon cancer

A vegetarian diet has led to a gene mutation that may make Indians more susceptible to inflammation, and by association, increased risk of heart disease and colon cancer, says a study.

Researchers from Cornell University analysed frequencies of the mutation in 234 primarily vegetarian Indians and 311 US individuals.

They found the gene variant associated with a vegetarian diet in 68 percent of the Indians and in just 18 percent of Americans.

The findings appeared in the online edition of the journal Molecular Biology and Evolution.

By using reference data from the 1000 Genomes Project, the research team provided evolutionary evidence that the vegetarian diet, over many generations, may have driven the higher frequency of a mutation in the Indian population.

The mutation, called rs66698963 and found in the FADS2 gene, is an insertion or deletion of a sequence of DNA that regulates the expression of two genes, FADS1 and FADS2.

These genes are key to making long chain polyunsaturated fats. Among these, arachidonic acid is a key target of the pharmaceutical industry because it is a central culprit for those at risk for heart disease, colon cancer, and many other inflammation-related conditions, the study said.

The genetic variation - called an allele - that has evolved in the vegetarian populations populations of India is also found in some African and East Asian population that have historically favoured vegetarian diets.

The vegetarian allele evolved in populations that have eaten a plant-based diet over hundreds of generations, the researchers said.

"Our analysis points to both previous studies and our results being driven by the same insertion of an additional small piece of DNA, an insertion which has a known function. We showed this insertion to be adaptive, hence of high frequency, in Indian and some African populations, which are vegetarian," said co-lead author of the study Kaixiong Ye.

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 study said.