East Asians tend to follow a traditional rice-based diet. It has led to a number of genomic adaptations which contribute towards the mitigation of obesity and diabetes. The University of Bologna conducted an international study which was published in the Evolutionary Applications Journal wherein it suggested an interesting hypothesis. The genomes of over 2,000 subjects from 124 South East Asian populations were compared and analysed by the researchers.
Marco Sazzini, the professor at the Department of Biology at the University of Bologna and the study coordinator suggests that it might be possible that some of the East Asian population whose ancestors began a rice-based diet at least 10,000 years ago had evolved genomic adaptations which mitigate the harmful effects on metabolism by a high-glycemic diet. These adaptations continue to play a huge role in protecting the population from the negative effects derived from the dietary alterations brought about by the westernization of lifestyles and globalisation. The alterations made today have led to an increase in the consumption of food that have a high glycemic index and are rich in processed sugar.
Rice tends to be rich in carbohydrates and has a high glycemic index. It means that once it has been ingested and digested, it would increase the amount of sugar in the blood. If rice is eaten regularly and in huge quantities, it might represent a risk factor towards developing insulin resistance. The same could be said for related metabolic diseases like type 2 diabetes. However, when compared with East Asians who have used rice as a staple for more than 10,000 along with those in the Indian Subcontinent, it was found that the latter experiences a higher rate of obesity and diabetes as compared to East Asians.
To better understand the difference between the two groups, it is best to take a look at archaeology. Findings in East Asia reveal that wild rice had been consumed by inhabitants of the region for the past 12,000 years. After the introduction of rice farming techniques, around 7,000 to 6,000 years ago, rice quickly spread throughout Japan and Korea. An independent rice domestication process started in the northern regions of the Indian Subcontinent 4,000 years ago.
The rice varieties used presented a lower glycemic index as compared to East Asian rice. Thus, according to Arianna Landini, a PhD student at the University of Edinburgh and the first author of the study, different rice varieties and the introduction of a rice-based diet a millennia ago have put populations in Japan, Korea, and China under greater metabolic stress as their South Asian counterparts. This resulted in genomic adaptations evolving and mitigating the risk of metabolic diseases and becoming ill. The study shows how studying evolutionary history helps with biomedical research.