ORGANISMS' diet can affect their DNA, Oxford scientists have discovered.

In a study on two groups of parasites, researchers detected differences in DNA sequences that could be attributed to the composition of their food.

Study co-author Dr Steven Kelly, from Oxford’s Department of Plant Sciences, said: "Organisms construct their DNA using building blocks they get from food.

"Our hypothesis was that the composition of this food could alter an organism’s DNA.

"For example, could a vegetarian panda have predictable genetic differences from a meat-eating polar bear?"

To test that hypothesis, Dr Kelley and his team picked groups of parasites which have a common ancestor but eat different food.

He went on: "We found that different levels of nitrogen in a parasite’s diet contributed to changes in its DNA. Specifically, parasites with low-nitrogen, high-sugar diets had DNA sequences that used less nitrogen than parasites with nitrogen-rich, high-protein diets."

The results, based on mathematical models developed by the researchers, reveal a previously hidden relationship between cellular metabolism and evolution.

They provide new insights into how DNA sequences can be influenced by adaptation to different diets, Oxford University said.

The results were published in the journal Genome Biology.