Personal “Mitotype” Could Explain Why High-Fat Diets Lead to Obesity and Diabetes in Some People

Scientists have identified a mutation in the mitochondrial genome that may contribute to diabetes and other health issues linked to high-fat diets.

A team from the University of New South Wales (UNSW) Sydney investigated the way different diets affect fruit fly populations. They found a discrepancy between two sets of Drosophila melanogaster fruit flies when feeding them a high-protein and a high-carbohydrate diet. Fruit fly larvae with a noted mitochondrial DNA (mtDNA) mutation showed a pronounced increase in development when eating a high-carbohydrate diet of banana, but stagnated on a high-protein diet of passionfruit. Conversely, fruit fly larvae without the mtDNA mutation thrived on the high-protein diet, but dropped in frequency when given carbohydrates.

According to Professor Bill Ballard, “What is unique about this study is we’ve identified one mutation in the mitochondrial genome, that when fed a specific diet is advantageous and causes the frequency of flies in a population cage to increase. Then when you swap the diet back to a high protein diet, the flies with the mutation go down in numbers and the other flies without the mutation go up.”

This was more than just a random, neutral mutation, explained Ph.D. student Sam Towarnicki: “The selective advantage is this—the larvae possessing the mutation fed on high-carbohydrate diet grow up nice and early and become adults before the others on the protein diet [also with a mutation]. And we found a 10% difference in the development just in one generation between those two groups, which is huge. And, because we followed 25 generations, those increases compound over time, which delivers much bigger numbers and a huge selective advantage.”

The researchers say that knowing a person’s “mitotype” will help that person optimize his or her diet.

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