Following a Mediterranean diet might be a recipe for a long life because it appears to keep people genetically younger, say US researchers.
Its mix of vegetables, olive oil, fresh fish and fruits may stop our DNA code from scrambling as we age, according to a study in the British Medical Journal.
Nurses who adhered to the diet had fewer signs of ageing in their cells.
The researchers from Boston followed the health of nearly 5,000 nurses over more than a decade.
The Mediterranean diet has been repeatedly linked to health gains, such as cutting the risk of heart disease.
Although it's not clear exactly what makes it so good, its key components - an abundance of fresh fruit and vegetables as well as poultry and fish, rather than lots of red meat, butter and animal fats - all have well documented beneficial effects on the body.
Foods rich in vitamins appear to provide a buffer against stress and damage of tissues and cells. And it appears from this latest study that a Mediterranean diet helps protect our DNA.
The researchers looked at tiny structures called telomeres that safeguard the ends of our chromosomes, which store our DNA code.
These protective caps prevent the loss of genetic information during cell division.
As we age and our cells divide, our telomeres get shorter - their structural integrity weakens, which can tell cells to stop dividing and die.
Experts believe telomere length offers a window on cellular ageing.
Shorter telomeres have been linked with a broad range of age-related diseases, including heart disease, and a variety of cancers.
In the study, nurses who largely stuck to eating a Mediterranean diet had longer, healthier telomeres.
No individual dietary component shone out as best, which the researchers say highlights the importance of having a well-rounded diet.
Independent experts said the findings were interesting but by no means conclusive.
Dr David Llewellyn, senior research fellow in clinical epidemiology at the University of Exeter, said: "All observational studies have the potential to produce misleading estimates, and we should not assume that the association with telomere length is necessarily causal.
"That said, this large well-conducted study is consistent with the hypothesis that dietary interventions may lead to substantial improvements in health."
The British Heart Foundation said: "These results reinforce our advice that eating a balanced and healthy diet can reduce your risk of developing heart disease."