Fruit flies can help us personalise what we eat – our DNA is similar to theirs

We share 98% of our DNA with primates, 97.5% with mice, and 60% with fruit flies. Yes, fruit flies.

And given we share key genetic ­features, fruit flies make excellent models for research, especially how diet affects health. The latest study, led by the ­University of Glasgow, suggests that small genetic changes can make bad diets good and good diets bad, if we can understand how genetics might shape our response to food.

The fruit fly has genes in tiny compartments inside its cells – and these shape how different foods affect the insects’ health. Human cells have the same compartments with similar genetics, and the researchers expect the same mechanisms may shape whether a diet is good or bad for us too.

Different people handle the same food differently – a good diet for one person may be less good for another. Keen to understand why, researchers from the University of Glasgow, Monash University in Australia and Germany’s Dresden University of Technology collaborated to examine how two different diets affected fruit fly health. They found genes can shape the impact of diet so strongly there may be no such thing as a good diet for everyone.

Variation between people is encoded genetically in our DNA which comes from two sources, the nucleus of the cell and a small amount from the mitochondria which are key in processing food. These two types of DNA interact, which may hold the key to why individuals respond differently to the same foods.

At the level of cells, genetics and metabolism, we’re very similar to fruit flies, and researchers can understand these processes more quickly in flies than in human beings. Studying responses to different foods in flies has some important implications for the health impact of a human diet.

When flies were fed high-protein or high-fat foods, scientists found that the different combinations of mitochondrial DNA and nuclear DNA dramatically altered the health impacts of the foods, to the extent that a dietary change was beneficial for some but lethal for others, a matter of life and death.

Dr Adam Dobson from Glasgow University, who led the study, said: “The biggest surprise was how dramatic some of these effects were. The genetic differences in the flies that we studied were able to completely change the effect of changing diet, from beneficial to toxic or even lethal. This suggests that we might need to understand how mitochondria and other parts of the cell work together if we want to improve human health by personalising diet.”