Abstract
Adoption of diets based on some cereals, especially on rice, signified an iconic change in nutritional habits for many Asian populations and a relevant challenge for their capability to maintain glucose homeostasis. Indeed, rice shows the highest carbohydrates content and glycemic index among the domesticated cereals and its usual ingestion represents a potential risk factor for developing insulin resistance and related metabolic diseases. Nevertheless, type 2 diabetes and obesity epidemiological patterns differ among Asian populations that rely on rice as a staple food, with higher diabetes prevalence and increased levels of central adiposity observed in people of South Asian ancestry rather than in East Asians. This may be at least partly due to the fact that populations from East Asian regions where wild rice or other cereals such as millet have been already consumed before their cultivation and/or were early domesticated have relied on these nutritional resources for a period long enough to have possibly evolved biological adaptations that counteract their detrimental side effects. To test such a hypothesis, we compared adaptive evolution of these populations with that of control groups from regions where the adoption of cereal‐based diets occurred many thousand years later and which were identified from a genome‐wide dataset including 2,379 individuals from 124 East Asian and South Asian populations. This revealed selective sweeps and polygenic adaptive mechanisms affecting functional pathways involved in fatty acids metabolism, cholesterol/triglycerides biosynthesis from carbohydrates, regulation of glucose homeostasis, and production of retinoic acid in Chinese Han and Tujia ethnic groups, as well as in people of Korean and Japanese ancestry. Accordingly, long‐standing rice‐ and/or millet‐based diets have possibly contributed to trigger the evolution of such biological adaptations, which might represent one of the factors that play a role in mitigating the metabolic risk of these East Asian populations.
Highlights
This is consistent with the fact that after the changes in dietary habits and lifestyle experienced by most Asian populations in the last decades, the number of individuals affected by type 2 diabetes (T2D) in these human groups has rapidly increased, until representing around 60% of the world's diabetic subjects (Hu, 2011)
Introduction of massive cereals consumption, in particular of rice, in the diet of the ancestors of Asian populations has represented a substantial challenge for their metabolism due to the outstanding carbohydrates content and glycemic index of such a nutritional resource with respect to other domesticated plants (Atkinson et al, 2008)
We investigated the adaptive evolution of populations whose ancestors inhabited the geographical areas where wild rice and/or millet originated and were early domesticated (i.e., Han and Tujia Chinese groups, Koreans, and Japanese people) and compared it with that of control groups from South East Asian and South Asian regions where cereals agriculture spread only more recently
Summary
This is consistent with the fact that after the changes in dietary habits and lifestyle experienced by most Asian populations in the last decades, the number of individuals affected by T2D in these human groups has rapidly increased, until representing around 60% of the world's diabetic subjects (Hu, 2011). To test such a hypothesis, we assembled a genome-wide “Pan-Asian” dataset including 2,379 individuals from 124 East Asian and South Asian populations selected to be representative of human genetic variation observable at geographical areas where wild rice or millet originated and/or were early domesticated (i.e., candidate populations) or where the adoption of cereal-based diets occurred only several thousand years later (i.e., control populations) (Table S1).
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