Many people try to stop eating meat but have a hard time sticking to a strict vegetarian diet. Some might chalk up this failure to a lack of willpower, but according to new research, their genetics may actually be to blame.
Scientists have discovered a handful of genes that are more common in vegetarians than in omnivores, which may help explain why some people seem to have an easier time giving up meat than others. They shared their findings in a new paper published Wednesday in the journal Plos One.
At least 6 percent of Americans—and possibly up to 10 or 15 percent—identify as vegetarian or vegan, wrote the Hill’s Daniel de Visé in 2022. However, many people who say they are vegetarians have reported eating red meat, poultry and fish in past studies.
This dichotomy got researchers thinking: Maybe some people really want to be vegetarians, but a biological or environmental barrier is preventing them from strictly adhering to this diet. They wondered if “there is something hard-wired here that people may be missing,” says study co-author Nabeel Yaseen, a pathologist at Northwestern University, in a statement.
To try to unravel this mystery, they turned to a large biomedical database called the UK Biobank. Since 2006, the biobank has collected blood, urine and saliva samples from roughly 500,000 residents of the United Kingdom between the ages of 40 and 69 at the time of recruitment. In addition to this biological data, which the biobank uses to sequence participants’ genomes, people provide detailed information about their lifestyles, including diet, physical activity, sleep and mental health.
For this new study, researchers analyzed data from 5,324 UK Biobank participants who identified as strict vegetarians, as well as from 329,455 who said they ate meat. All participants included in this study were white and Caucasian.
When the researchers looked at these people’s DNA, they discovered a connection between their self-reported diets and genetics. More specifically, the team noticed that three genes were significantly more common among the vegetarians. Two of those variants—called NPC1 and RMC—are involved in fat metabolism and brain function. The third, RIOK3, plays a variety of roles in the body, including supporting the immune system.
On top of those three, the team found another 31 genes they say could potentially be associated with vegetarianism.
The scientists are still teasing out exactly what these correlations might mean. But they suspect some people lacking these genes may need to eat meat to get certain fatty lipids, while the bodies of people with these genes may be able to produce the lipids internally.
“Maybe there’s some fat that’s essential for some people to have in their diet but not for others,” Yaseen tells New Scientist’s Clare Wilson.
Past research has found other links between genetics and diet, including whether people like black coffee or grapes and orange juice. Genes may also be responsible for why some people love cilantro, while others think it tastes like soap.
However, genes aren’t the only thing affecting diet: “An environment can completely counteract something that is highly heritable, and the same goes with vegetarianism,” Laura Wesseldijk, a behavioral geneticist at Amsterdam University Medical Centers who did not participate in the new study but has researched the heritability of vegetarianism, tells NBC News’ Katie Mogg.
Whatever the underlying mechanisms at play, this study opens the door for further research that could help scientists, doctors and entrepreneurs—specifically those developing meat alternatives—to understand more about what goes into individuals’ dietary choices.
“We hope that future research will shed further light on the physiology of vegetarianism and enable us to provide better, personalized dietary recommendations and produce better meat substitutes,” Yaseen tells Live Science’s Emily Cooke.