People who eat a lot of industrially processed junk food are more likely to exhibit a change in their chromosomes linked to ageing, according to research presented Tuesday at an online medical conference.

Three or more servings of so-called "ultra-processed food" per day doubled the odds that strands of DNA and proteins called telomeres, found on the end of chromosomes, would be shorter compared to people who rarely consumed such foods, scientists reported at the European and International Conference on Obesity.

Short telomeres are a marker of biological ageing at the cellular level, and the study suggests that diet is a factor in driving the cells to age faster.

While the correlation is strong, however, the causal relationship between eating highly processed foods and diminished telomeres remains speculative, the authors cautioned.

Each human cell has 23 pairs of chromosomes that contain our genetic code. Telomeres do not carry genetic information, but are vital for preserving the stability and integrity of chromosomes and, by extension, the DNA that all the cells in our body relies on to function.

As we get older, our telomeres shorten naturally because each time a cell divides, part of the telomere is lost.  That reduction in length has long been recognised as a marker of biological age.

Earlier studies had pointed to a possible link with sugar-sweetened drinks, processed meats and other foods loaded with saturated fats and sugar, but the findings were inconclusive.