Vegetarian diet: How genes can influence how well you adhere

  • Vegetarianism has been practiced worldwide for thousands of years for cultural, moral, and health reasons.
  • Researchers now say some people may be more genetically predisposed to choose to follow a vegetarian dietary pattern.
  • Experts point out that genetics are often only one factor out of many in determining health outcomes.

Some people may find it difficult to maintain a strictly vegetarian diet.

According to new research, your genes may help explain why.

A study published today in the scientific journal PLOS One notes that vegetarians make up less than 5% of the U.S. population and about half to two-thirds of self-identified vegetarians consume fish, poultry, or red meat at least occasionally.

The researchers suggest that genetic factors may help explain why some people adhere to a strictly vegetarian diet while others do not.

So how did they test their theory, what did they find, and what do experts have to say about it?

Linking SNPs and diet

Participants in this study were selected from the UK Biobank, a database that includes about 500,000 people.

Samples — including blood — were collected from each participant, allowing the researches to identify single-nucleotide polymorphisms (SNPs, pronounced snips).

SNPs are a common type of genetic variation. Everyone has many SNPs and they help to determine a variety of biological characteristics — from eye color to disease susceptibility — in a complex interplay with each other.

Some SNPs affect both metabolism and brain function and could potentially make it more or less difficult for your body to function properly while on a vegetarian diet.

Participants in the study also completed at least one of two dietary questionnaires. One was a general dietary questionnaire and the second asked participants to recall their diet from the previous 24 hours.

After screening, the study retained 5,324 vegetarians and 329,455 control subjects.

The SNPs of each group were analyzed and compared to each other to determine whether certain SNPs were associated with a vegetarian diet.

In the end, 11 specific genes were identified by researchers as potential contributors to vegetarianism.

Limitations to the vegetarian diet study

Does this mean that your diet is predetermined by your genes? Not quite, experts say.

“This study does not in fact show any causational role of these potentially vegetarian SNPs,” said Megan Wroe, a wellness manager and registered dietitian at the Wellness Center of Providence St. Jude Medical Center in California who was not involved in the study.

“Even if these SNPs were found in a genetic assessment, it does not mean, based on this data, that they should in fact follow a vegetarian diet or that anything negative would happen if they didn’t,” Wroe told Medical News Today.

“Just like anything else, you can have a genetic predisposition but never see that outcome. You can show you have genetic risk factors for cancer and never get cancer. There are too many other factors at play such as movement, stress, and environmental toxins,” she added.

There are other reasons to be cautious with these results, experts advised.

“The study was well done overall, but any time you use food journals and recalls as the main identifying factor of how a person eats you run into unreliable data,” said Wroe.

“The findings from this study are not generalizable since the people who participated in the study tended to be female, older, healthier, and of high socioeconomic status,” said Dr. Amanda Velazquez, the director of Obesity Medicine at the Center for Weight Management and Metabolic Health at Cedars Sinai Medical Center in Los Angeles who was not involved in the study.

“We have to be cautious to apply these findings to the entire population until more research is done to study more diverse populations,” Velazquez told Medical News Today.

The health benefits (and risks) of vegetarianism

While many people choose vegetarianism for cultural, moral, religious, or environmental reasons, the diet plan also can affect your health.

“This study defines vegetarian as not eating any animal flesh or product at all, which is actually vegan. I typically do not recommend a strict vegan diet for most people. Vegetarian, pescatarian, or omnivorous with small portions of sustainably raised meat are the most health-promoting diets for majority of people,” said Wroe.

Jordan Hill, the lead registered dietitian with Top Nutrition Coaching, told Medical News Today that “some of the potential health benefits from following a vegetarian diet include reduced risk for chronic diseases, weight management, and improved digestion.”

“With an emphasis on plant foods, fruits, and vegetables, those that follow a vegetarian diet may intake more fiber, micronutrients, and antioxidants than their counterparts,” said Hill, who was not involved in the study.

“It’s important to note that a vegetarian diet can still include unhealthy processed foods, which may not support the previously mentioned health benefits,” she added.

There are also certain insufficiencies associated with a vegetarian diet that you also should be aware of.

“Risks associated with following a vegetarian diet include potential nutrient deficiencies, like vitamin B12, iron, calcium, and omega-3 fatty acids, as well as inadequate protein intake,” said Hill.

How to eat healthier (regardless of SNPs)

Some people may decide that a strictly vegetarian diet isn’t for them, but that doesn’t mean they will be in poor health.

“It’s important for individuals to make dietary choices that align with their personal preferences and cultural factors, in addition to their overall health goals. There’s no right or wrong way to eat and finding what’s best for the individual is encouraged,” said Hill.

“The healthier types of meat are categorized as lean meat. Examples of lean meat include chicken, turkey, and fish. As it relates to red meat, the World Cancer Research Fund International generally recommends to limit red meat consumption to three servings per week with a serving being four to six ounces,” Hill advised.

“We should aim to minimize factory farmed meat as much as possible, but I am a big advocate of including grass-fed or pasture-raised meats on a regular basis for the quality nutrients they provide that cannot be obtained from plants,” said Wroe.

The idea of either eating meat or not eating meat doesn’t necessarily have to be a strict choice either.

“Focus less on whether you need to follow vegan or vegetarian or flexitarian diet… and simply start cooking and using less highly processed packaged products. Most of us would be so much healthier if we simply ate homemade food more often,” said Wroe.

If you’re considering switching to a meatless diet, experts recommend making the transition gradually.

“Start including vegetarian protein sources such as beans, lentils, nuts, and seeds. Try substituting one of these for an animal protein daily,” said Velazquez.

“Often times in diet culture, we have viewed it as ‘all or nothing’ and forget that even small steps can make a difference,” Velazquez added.

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