Writing in the journal Cell Metabolism, the international research team used an animal model to test the impact of ancestors diet on risk for metabolic and lifestyle diseases such as obesity and diabetes.
Findings from the rat research suggested that the emerging middle classes from developing countries may be more susceptible than western Caucasians to obesity, type 2 diabetes and cardiovascular disease as a result of the chronic under-nutrition endured by their ancestors.
Led by Professor Anandwardhan Hardikar's team at the University of Sydney, the 12-year, multi-generational rat study suggests that because recent ancestors were exposed to chronic malnutrition, the populations' epigenetic makeup (whereby changing environmental factors alter how people's genes are expressed) has not compensated for these dietary changes.
"Their adverse metabolic state was not reversed by two generations of nutrient recuperation through a normal diet," said Hardikar. "Instead this newly prosperous population favoured storage of the excess nutrients as fat leading to increased obesity, cardiovascular disease and metabolic risk for diabetes when compared to their 'developed world' counterparts.
According to the team, this means their bodies are still designed to cope with undernourishment; so they store fat in a manner that makes them more prone to obesity and its resulting diseases than populations accustomed to several generations of a 'normal' diet.
The research team performed the multi-generational study on two groups of rats. The first group was undernourished for 50 generations and then put on a normal diet for two generations – so mimicking the situation in many developing countries where recent increased prosperity has led to a sudden increase in calories – from undernourished to a ‘normal’ diet.
Meanwhile, the second (control) group maintained a normal diet for 52 generations.
At the end of the study it was found that when the descendants of the first group were exposed to a normal diet, this did not reverse the epigenetic modifications made by their undernourished forebears.
In fact, these rats were eight times more likely to develop diabetes and multiple metabolic defects when compared to the control group.
They concluded that eating a 'normal' diet can make animals, and possibly people, overweight, if their ancestors had been undernourished for several generations.
Biomarkers of risk?
Hardikar also suggested that lower Vitamin B12 levels in the undernourished rats could also be an indicator of the trend – a and is also something that has been suggested in humans.
"Human studies from Ranjan Yajnik's group at KEM Hospital in Pune, India have demonstrated that low circulating B12 and high folate levels are associated with insulin resistance and type 2 diabetes,” he commented.
"Hopefully further research in understanding the gut microbes, which are major producers of Vitamin B12 in our body, and/or dietary supplementation with Vitamin B12 and other micronutrients, could reduce the risk of metabolic diseases in the coming generations," Hardikar added.