Stop Tweeting that "Vegetarian Diets Increase Risk of Cancer" Headline. It's Wrong. Seriously, It's Wrong
April 4, 2016
Just a few days ago many of us may have seen this headline pop into our Facebook or Twitter feeds:
Or this one:
Or this one:
As soon as these eye-catching headlines were published, they were retweeted like wildfire. Many people seemed to feel positively gleeful about the idea that a vegetarian diet might increase their risk for disease! A haha to all those righteous vegans.
If you don’t believe me, search “vegetarian study” on Twitter and see how thrilled some tweets are. Sure it's satisfying to think that your sanctimonious vegetarian friends have been wrong all along...
Except, they’re not. Sorry. These headlines are so misleading as to be completely wrong.
What was the study actually about?
The study analyzed the genes of people who are part of populations that have been vegetarian for generations (including East Asian and Indian populations). In these populations there is a high prevalence of a genotype, called I/I, that allows them to more efficiently convert the omega-6 fatty acid, linoleic acid, to arachidonic acid. Arachidonic acid, which is primarily found in animal foods, can contribute to inflammation and increase risk for disease when consumed in too high amounts. For populations who long subsisted on plant-based diets, this gene provided an advantaged, because it allowed them to make enough of the necessary arachidonic acid. However, now that vegetable oils are prevalent in the food system, it may cause those who carry the gene to produce too much.
The authors of the study are dismayed by the way their results were treated in the press. Nutrition Wonk corresponded with Kaixiong Ye, PhD, a postdoc who performed the evolutionary analysis for the paper. Via email, he expressed “We are quite sad to see the misinterpretation of our study.”
What does the study actually mean?
Ye explained what the study means for us, and importantly, for any current or future vegetarians.
Will eating vegetarian or high omega-6 acids change genes within your lifetime? Or increase your risk of colorectal cancer and heart disease if you don't already have the allele?
“NO!" Ye explains, "The 'vegetarian allele' we found occurred tens of thousands of years ago, randomly. It later became more common in vegetarian populations. The mutation happened way before the vegetarian lifestyle! For someone who sticks to vegetarian diet for his/her lifetime, the diet won't cause mutation and won't change the genome because vegetables are not mutagens.”
So, when these misleading headlines say “long term,” they don’t mean a couple of decades, they mean thousands of years. Being a lifelong vegetarian will not change the way you convert linoleic acid to arachidonic acid.
If you DO likely have the I/I genotype because, for example, you are Indian or East Asian, what should you do?
Ye says, “Our advice for individuals with I/I genotype is 'do what your ancestors have been doing, eat a more natural vegetarian diet, and avoid eating too much vegetable oil and meat.'
"For those without this vegetarian gene, our advice is: 'a strict vegetarian diet is not sufficient for you, you may not have enough arachidonic acid, so you can add some vegetable oil or meat to your diet.'
"In short, the most important thing is: 'match your diet to your genes!’”
For those following along, advice to avoid meat continues for people with the I/I allele. This is NOT proof that a diet with meat is somehow healthier for these folks, which is what some outlets have suggested.
In fact, Ye says, avoiding a vegetarian diet is the exact WRONG thing to do if you have the allele. “People should stick to vegetarian diet (without too much vegetable oil).”
But for people who are vegetarians without the allele, the advice is slightly different. They may actually need a little vegetable oil (or maybe small amounts of meat) to increase total arachidonic acid to meet biological needs.
“Healthier oils,” Ye explains, “are those that are low in omega-6 fatty acids, but high in omega-3 fatty acids, such as flaxseed oil and canola oil.”
So, there you have it. You can still be a vegetarian and stay healthy OR choose not to be a vegetarian and also be healthy!
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