Researchers trace preference for vegetarian diet to genetic variation among populations

Cornell University researchers have identified a genetic variation that, they say, had evolved in populations that favoured vegetarian diets over hundreds of generations. The geography of the vegetarian allele, a variant form of a gene, was vast and included people from India, Africa and parts of East Asia that had green diets even today.

According to researcher Kaixiong Ye, the vegetarian adaptation allowed people to ''efficiently process omega-3 and omega-6 fatty acids and convert them into compounds essential for early brain development.''

Omega-3 is found in fish, whole grains, olive oil, fruits, and vegetables, while omega-6 was present in beef, pork products and many packaged snack foods such as cookies, candies, cakes, and chips, as also in nuts and vegetable oils.

According to nutritionists getting the two types of fatty acids in the right balance in the diet was essential to health. The substances cannot be produced  in the body and have to be obtained from food.

Omega-3, which is anti-inflammatory helps in the regulation of metabolism, which affects a wide range of functions in the body. Omega-6 contributed to inflammation and played an important role in skin and hair growth, bone health and reproductive health. However, while  inflammatory responses were essential to survival, and helped fight off infections and protect from injury, in case of excessive response, it could lead to a variety of problems. These included a higher risk of heart disease, cancer and Alzheimer's disease.

The discovery by researchers including Kumar Kothapalli from Cornell University in the US provided the first evolutionary investigation that traced a higher frequency of a particular mutation to a primarily vegetarian population from Pune (about 70 per cent), as against a traditional meat-eating US population, made up of mostly Kansans (less than 20 per cent).

By using reference data from the 1000 Genomes Project, researchers provided evolutionary evidence that the vegetarian diet, over many generations, might have led to the  higher frequency of a mutation in the Indian population.

The mutation, called rs66698963 and found in the FADS2 gene, was an insertion or deletion of a sequence of DNA that regulated the expression of two genes, FADS1 and FADS2, which are key to making long chain polyunsaturated fats, researchers said.

According to the researchers, among these arachidonic acid was a key target of the pharmaceutical industry as it was a central culprit for those at risk for heart disease, colon cancer, and many other inflammation-related conditions, they said.

''With little animal food in the diet, the long chain polyunsaturated fatty acids must be made metabolically from plant PUFA precursors,'' the researchers said.