Your Genes May Stop You Being Vegetarian, Scientists Say

While some people seem to effortlessly adopt a vegetarian diet, others find it nearly impossible to quit meat.

According to new research from Northwestern University, your ability to stick to a strict vegetarian diet might actually come down to your genes.

As of January 2022, roughly one in 10 American adults identified themselves as being either vegan or vegetarian, according to surveys carried out by Kansas State University. Motivations for adopting a plant-based diet vary between individuals and can include personal health, animal wellbeing, environmental concerns and religious reasons., Previous studies have shown that roughly half of all self-described vegetarians actually eat meat, at least occasionally.

"This suggests that many people who would like to be vegetarian are unable to stick to a strict vegetarian diet," study author and Professor Emeritus of pathology at Northwestern University's Feinberg School of Medicine, Nabeel Yaseen, told Newsweek. "Given that several prior studies have shown that food choices are strongly influenced by genetics, we wanted to see if adhering to a strict vegetarian diet is influenced by genetics."

Using data from UK Biobank, a large-scale biomedical database of in-depth genetic and health information from half a million U.K. participants, the team identified 5,324 strict vegetarians and 329,455 people who ate meat. "We then compared the genetic data of strict vegetarians to non-vegetarians by a genome-wide association study (GWAS) to identify genes that might be associated with vegetarianism," Yaseen said. The study was published on Wednesday in the journal PLOS One.

A genome-wide association study is a scientific research method that involves rapidly scanning the DNA of a group of individuals to find distinctive markers of a particular disease (or in this case lifestyle). Using this method, the team identified three genetic variants that were more common in people with a strict vegetarian diet.

"Our study is the first fully peer-reviewed and indexed study to address the genetics of vegetarianism," Yaseen said. "We identified three genes that are significantly associated with vegetarianism as well as 31 other genes that are possibly associated with vegetarianism. As it turns out, several of the genes we identified have important functions in lipid [fat] metabolism and brain function."

Sylvain Charlebois, a professor in environmental studies and scientific director of the Agri-Food Analytics Lab at Dalhousie University, in Canada, explained how these genes could impact our capacity to adhere to a strict vegetarian diet. "While the exact mechanism isn't fully understood, it's speculated that individuals with genetics favoring vegetarianism may be able to synthesize specific lipid components found in meat," Charlebois, who was not involved in the study, told Newsweek. "This suggests that their bodies might not have the same 'craving' for meat-related components as others, making them more inclined toward a vegetarian diet."

However, before blaming your genes for your insatiable cravings for chicken nuggets, there are several caveats to consider here.

"We need to be careful with how we interpret the results of this study," Charlebois said. "Food is culture, it is about traditions, and most importantly, it is inherently personal. While genetics may play a role, it's important not to oversimplify the complexity of human dietary habits based solely on genetic markers."

It is also important to remember that genome-wide association studies (GWAS) like this simply look for patterns and correlations within a group of individuals. These correlations do not necessarily imply that a specific gene causes the observed behavior. "By definition, [GWAS] involve association analysis," Maria Traka, deputy head of Food and Nutrition National Bioscience Research Infrastructure at the Quadram Institute in the U.K., told Newsweek. "In addition, dietary habits are complex and are highly correlated both with each other and with non-dietary traits. So single dietary habits may represent broader diet and lifestyle choices."

Nicola Pirastu, senior manager at the Biostatistics Unit for the Italian research institute, Human Technopole, agreed, saying that this data alone was not enough to make solid conclusions about the genetic basis for plant-based diets. "The evidence I am afraid is not strong enough to make such claims and these results are unlikely to replicate in larger studies," he told Newsweek. "More specific and larger studies are likely to find sturdier results.

"A genetic variant may contribute to vegetarianism, for example increasing the liking to vegetables and thus making this choice simpler, but the differences we have detected can hardly explain the actual choice. This does not mean that we should not try to understand the biological bases of food choices and liking as they could potentially help us in improving people's food choices, but this needs a broader approach, not focused on a single food or behavior but that tries to incorporate the complexity involved."

Yaseen, too, said that more research was needed to understand these biological underpinnings. "Our data suggests that the ability of some people, but not others, to adhere to a strict vegetarian diet may be related to genetic differences in lipid metabolism and brain function. However, more research is needed in order to further examine this hypothesis. A better understanding of the genetics and physiology of vegetarianism may allow us to provide better personalized dietary recommendations and perhaps enable the production of better meat substitutes."