Vulnerability to type 2 diabetes
Ancestral diets determine vulnerability to type 2 diabetes
The middle classes from developing countries are more
susceptible than western Caucasians to obesity, type 2 diabetes and
cardiovascular disease in today's changing environment. New
research published inCell Metabolismreveals this may be a result of
the nutrition endured by their ancestors.
The findings in the paper titled 'Multigenerational
undernutrition and diabetes' could explain projections that more
than 70 per cent of the global burden of type 2 diabetes will fall
on individuals from developing countries by 2030.
This latest research demonstrates that eating a 'normal' diet
can make animals obese, if their ancestors had been undernourished
for several generations.
Unsurprisingly, increasing prosperity in developing countries
has been accompanied by a sudden increase in caloric intake.
However, their populations' epigenetic makeup, whereby changing
environmental factors alter how people's genes are expressed, has
not compensated for these dietary changes. 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
This scenario was recreated in a 12-year study of two groups of
rats. The first group was undernourished for 50 generations and
then put on a normal diet for two generations. The second (control)
group maintained a normal diet for 52 generations. At the end of
the study, 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. These rats were eight times
more likely to develop diabetes and multiple metabolic defects than
the control group.
'Their adverse metabolic state was not reversed by two
generations of nutrient recuperation through a normal diet,' said
Professor Hardikar. 'Instead, this newly prosperous population
favoured storage of the excess nutrients as fat, leading to
obesity, cardiovascular disease and metabolic risk of diabetes when
compared to their "developed world" counterparts.' Professor
Hardikar said lower Vitamin B12 levels in the undernourished rats
could also be an indicator of this trend. '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.'
With increasing migration of populations from developing to
affluent countries, there is a need to identify factors that
minimise their risk of diabetes and obesity-one of Australia's
national health priorities.
Associate Professor Hardikar is an Australian Future Fellow
(ARC) and group leader, Diabetes and Islet Biology, at the CTC. The
work was done by his team with colleagues from the National Centre
for Cell Science, KEM Hospital and the DYP Medical College, Pune,
15 July 2015