Researchers have found that a switch from animal-based diets to vegetarianism marks Europeans’ genes, which led to proper human brain development, controlling inflammation and immune response.

Based on one's ancestry, clinicians may one day tailor each person's diet to her or his genome to improve health and prevent disease.A study describes how shifts in the diets of Europeans after the introduction of farming 10,000 years ago led to genetic adaptations that favoured the dietary trends of the time.Before the Neolithic revolution that began around 10,000 years ago, European populations were hunter-gatherers that ate animal-based diets and some seafood.But after the advent of farming in southern Europe around 8,000 years ago, European farmers switched to primarily plant-heavy diets.

The results revealed that these dietary practices are reflected in the genes of Europeans that has played in the evolution of human population.Study’s senior author Alon Keinan and lead author Kaixiong Ye from Cornell University conducted the study.The study has implications for the growing field of nutritional genomics, called nutrigenomics.The findings revealed that vegetarian diets of European farmers led to an increased frequency of an allele — each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome — that encodes cells to produce enzymes that helped farmers metabolize plants.The FADS1 gene found in these vegetarian farmers produces enzymes that play a vital role in the biosynthesis of omega-3 and omega-6 long-chain polyunsaturated fatty acids (LCPUFA).These LCPUFAs are crucial for proper human brain development, controlling inflammation and immune response.While omega-3 and omega-6 LCPUFA can be obtained directly from animal-based diets, they are absent from plant-based diets.Vegetarians require FADS1 enzymes to biosynthesize LCPUFA from short-chain fatty acids found in plants (roots, vegetables and seeds).

Analysis of ancient DNA revealed that prior to humans' farming, the animal-based diets of European hunter-gatherers predominantly favoured the opposite version of the same gene, which limits the activity of FADS1 enzymes and is better suited for people with meat and seafood-based diets.All farmers relied heavily on plant-based diets, but that reliance was stronger in the south, as compared to northern Europeans - whose farmer ancestors drank more milk and included seafood in their diet.Plant-based alleles regulate cholesterol levels and have been associated with risk of many diseases, including inflammatory bowel disease, cardiovascular disease, arthritis and bipolar disorder.The authors noted that future studies will investigate additional links between genetic variation, diets and health, so that "in the future, they can provide dietary recommendations that are personalised to one's genetic background.