The research, which identified a set of genes associated with people who followed a vegetarian diet for at least a year, was published Wednesday in the journal PLOS ONE.
Nabeel Yaseen, the study’s lead author and a professor emeritus of pathology at Northwestern University, said the findings may indicate that sticking with vegetarianism isn’t just a matter of willpower.
“The take-home message is that a vegetarian diet may or may not be appropriate for you based on your genetics,” Yaseen said. “You don’t have to beat yourself up if it’s something you can’t really stick with.”
The study compared the genetics of thousands of vegetarians and meat-eaters who shared their medical and lifestyle data with the UK Biobank, a biomedical research database containing information from about half a million participants in the UK.
The study identified three genes significantly associated with a vegetarian lifestyle by analyzing data from approximately 5,300 vegetarians and 329,000 meat-eaters. All three are located on a chromosome that contains genes involved in brain function and lipid metabolism – the process by which fats are broken down for energy.
The results also pointed to 31 other genes that were also associated with vegetarianism, although more weakly. Several of these genes also play a role in lipid metabolism.
“We hypothesize that perhaps one’s ability to maintain a vegetarian diet has something to do with how they handle fats in their body and how that affects brain function,” Yaseen said.
However, he added that the study only highlights a genetic link and does not claim that certain genes directly cause people to prefer a vegetarian diet.
For the study, Yaseen and his team focused on people they considered strict vegetarians: Those who had not consumed animal flesh or meat products for at least a year. They used two questionnaires that participants filled out for the British Biobank to determine who qualified. The first, administered four times between 2006 and 2019, asked participants to self-report whether they had eaten meat within the past year. The second, which asked people to record everything they had eaten within the previous 24 hours, was administered five times between 2009 and 2012.
Yaseen, for his part, pointed out a couple of important limitations of his study: For one, the research included only white Caucasians. Other ethnicities were excluded, he said, to ensure that genes that might be associated with a particular race weren’t falsely linked to vegetarianism. Thus, the research would need to be repeated in other groups to determine whether the findings apply more broadly.
Second, the study looked at only a small fraction of the human genome, leaving open the possibility that additional genes could be associated with vegetarianism.
Yaseen said he has no immediate plans for further research on the topic, but he envisions a time in the future – after much more research is completed – when it might be possible for experts to assess whether a vegetarian diet is a good fit for an individual based on their DNA.
“Hopefully we’ll know more, and maybe we’ll be able to test people genetically and say, ‘OK, you know, this diet is good for you, or this diet is not good for you’ – like having more personalized dietary recommendations.”