Scientists at Aberdeen University have discovered a genetic “switch” which they believe makes Europeans far more likely to choose high-fat food and alcohol than people in Asia. The findings also have implications for depression.
The switch – essentially a piece of DNA which turns genes on and off within cells, and which is also known as an enhancer – has remained unchanged for 300 million years, according to the researchers at the university’s Kosterlitz Centre. This particular switch controls the galanin gene, which regulates appetite and thirst in the hypothalamus area of the brain.
Peterhead scientist Dr Scott Davidson, who found the switch, explained that while our genes – 25,000 of them in every cell – are near-identical in all mammals, what makes us different from other species – and, indeed, from each other – is when, where and how the genes are turned off and on during development (as embryos) and throughout life.
“Not all cells turn on all genes at once,” Dr Davidson said. “Something organises which genes are turned on in different cells and we call them enhancers or switches.”
The switch is, however, different in some people and, when different racial groups were compared, it was found it was weaker in 16 per cent of Europeans and 30 per cent of Asians.
Dr Alasdair MacKenzie, who led the research, said that if the switch was turned on too strongly, then people were more likely to crave fatty foods and alcohol. “The fact that the weaker switch is found more frequently in Asians compared to Europeans suggests they are less inclined to select such options.”
Dr MacKenzie suggests that we can probably blame our ancestors’ way of life for the tendency. “These results give us a glimpse into early European life where brewing and dairy produce were important sources of calories during the winter months,” he said.
“Thus, a preference for food with a higher fat and alcohol content would have been important for survival. The negative effects of fat and alcohol we see today would not have mattered so much then as life expectancies were between 30–40 years.”
The study, published in the Journal of Neuropsychopharmacology, also found that changes in the same switch were linked to depression, because galanin is also produced in the anxiety and fear-controlling amygdala part of the brain. Recent research conducted by a team at the Institute of Psychiatry in London showed that the galanin gene is linked to depression and that part of a relevant gene is strongly related to the Aberdeen team’s switch.
There is hope that we can overturn the millennia of genetic determination, however – we might be able to get a pill to sort it out. “This has already allowed us to identify potential drug targets that will be used to develop a whole new generation of antidepressants as well as drugs to reduce cravings for fatty food and alcohol,” Dr Davidson added.
“It is possible that during the winter individuals with the weaker switch may not have survived as well in Europe as those with the stronger switch and as a result those in the west have evolved to favour a high fat and alcohol rich diet.”