Summary: Shifts in diets 10,000 years ago led to genetic adaptations that coded for a preference for dietary trends of that time, suggests a new study published in the journal Nature Ecology & Evolution. The findings might help researchers to build custom-made diets based on a person’s genome to boost health, and protect from disease, a field of research known as nutrigenomics.
Shift in diet changes DNA
The advent of farming 10,000 years ago led to a change in the DNA of Europeans. Prior to this era (the Neolithic revolution), Europeans were mainly hunter-gatherers whose diets were composed of animal meat and seafood. Then, the development of agriculture in the south of Europe, 8,000 years ago, led to shifts in their diets: the people took to plant-based meals more, and their dietary practices were eventually ‘written’ in their genes. These people underwent genetic adaptations favouring diets of that time.
The findings show the important role of diet in the evolution of humans, explains study senior author Alon Keinan.
Why the diet-caused genetic change?!
Switching to vegetarian diets led to genetic changes that assisted the European at metabolising plants: their bodies would make more of specific enzymes that would enable them to better consume plants as a result of an increased frequency in an allele (a form of a gene) coding for the enzyme-producing cells. The genes had an greater frequency because of natural selection. Given that the diets were mostly plant-based, vegetarian farmers possessing this allele (FADS1 gene) had the upper hand over those who did not express it as they could consume the plants better, leading to better health, and better chances at having more children. This means that the former farmers would pass down this allele to their offspring, eventually leading to a larger frequency of this genetic variant among the populations.
Vegetarians need the gene while non-vegs don’t!
The FADS1 gene produces enzymes involved in the biosynthesis of omega-3 and omega-6 long-chain polyunsaturated fatty acids (LCPUFA), the latter being extremely important for human brain development, and for monitoring inflammation and immune system. Omega-3 and omega-6 LCPUFA are absent from plant-based diets (while they can be obtained from animal-based ones), implying that vegetarians need the FADS1 enzymes to make the molecules from what they eat of plants, while their non-veg counterparts did not require the enzymes in large amounts because they already obtained the nutrients from their food source.
Before farming and the switch to vegetarian meals, the European hunter-gatherers showed a greater frequency in the counterpart of the allele in question, thus restricting the FADS1 enzymes because there was no need for a large amount of the enzymes to create the omega molecules as the people were obtaining them directly from the animals they consumed.
Plant-based alleles & diseases
Furthermore, the authors explain that plant-based alleles might have a role in regulating cholesterol levels, and risk of diseases like inflammatory bowel disease, cardiovascular disease, arthritis and bipolar disorder. Study lead author Kaixiong Ye says that they will need to do further research in order to find the associations between genetic variation, and diet and health.
“I want to know how different individuals respond differently to the same diet,” says Ye. “…in the future, we can provide dietary recommendations that are personalized to one’s genetic background.”