Some people today are hardwired to have improved health when on a vegetarian diet, suggests new research that reveals how our ancestors' food choices continue to impact human health today.
In this case, cultures from certain parts of India, Africa and Asia have eaten a mostly vegetarian diet for so long that they have evolved a genetic adaption that boosts their body's ability to process certain fatty acids, according to the new study, which is published in the journal Molecular Biology and Evolution.
If these individuals stray from their veggie-based diets, they may be at a higher risk than other people for heart disease, colon cancer and additional health problems associated with increased inflammation, the scientists believe.
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"With little animal food in the diet, the long chain polyunsaturated fatty acids must be made metabolically" from ingested plant products, co-authors Tom Brenna and Kumar Kothapalli of Cornell University explained in a joint comment in a press release.
They continued that "the physiological demand" for these necessary fatty acids "in vegetarians is likely to have favored genetics that support efficient synthesis of these key metabolites. Changes in the dietary omega-6 to omega-3 balance may contribute to the increase in chronic disease seen in some developing countries."
Fish and meats can be sources of these fatty acids. In plants, omega-6 may be found in wheat germ and various vegetables, such as corn. Many veggies are high in omega-3, such as broccoli, squash, Brussels sprouts, cauliflower and kale.
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Brenna, Kothapalli and Keinan identified the genetic mutation - called rs66698963 and found in the FADS2 gene - after analyzing the genomes of a primarily vegetarian population from Pune, India. They compared the genomes to those from Kansans, many of whom love their red meat. The cattle industry in Kansas is among the most lucrative in the United States.
The scientists then looked for the genetic mutation in other populations around the world, and noticed that the same pattern corresponding to long-standing vegetarian diets. The mutation has spread to people from parts of South America, Northern Europe and likely to other locations.
The same genetic sequence was deleted in other cultures, though. For example, indigenous people of northern Canada and parts of Greenland and Alaska (called the Inuit) show no signs of the mutation. The ancestors of the Inuit have eaten a mostly fish and other marine-based diet for thousands of years.
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"This is the most unique scenario of local (genetic) adaptation that I had the pleasure of helping uncover," population geneticist and lead author Keinan said.
He clarified that the mutation, which is really just a small added piece of DNA, occurs with "high frequency in Indian and some African populations, which are vegetarian. However, when it reached the Greenlandic Inuit, with their marine diet, it became maladaptive."
The findings, published in the journal Molecular Biology and Evolution, suggest that there is no one Paleo diet for all of us. In future, diets might instead be based on what your particular ancestors historically ate over multiple generations. So far, just this veggie-associated genetic mutation has been discovered, but other such adaptations in our genomes related to diet could be found in future.
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At the very least, the findings seem to prove the old adage "we are what we eat," given that our bodies, over the course of many generations, can evolve optimal ways of processing the foods that make up the majority of our diets.