December 2, 2014

expert reaction to Mediterranean diet and telomere length

A study published in The BMJ has explored a link between adherence to a Mediterranean diet and the length of telomeres, the ends of chromosomes, which have in the past been associated with ageing. They report that telomeres were longer in those with greater adherence to a Mediterranean diet.

Dr David Llewellyn, Senior Research Fellow in Clinical Epidemiology, University of Exeter, said:

“The lifestyles and environments of people who adhere to a Mediterranean diet may also differ in other important ways. Crous-Bou and colleagues sensibly adjust for factors such as smoking and physical activity, though additional unmeasured or uncontrolled factors such as exposure to chemicals, stress, alcohol consumption and medication use may also play a role. In this way 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. Exploring the relationship between diet and biological markers of ageing provides new clues about the processes that may contribute to the development of key age-related conditions such as dementia, cancer and cardiovascular disease.”

Prof Naveed Sattar, Professor of Metabolic Medicine, University of Glasgow, said:

“The extent we believe the value of an intervention of change in lifestyle depends on how well that change is related to a meaningful outcome or surrogate outcome. In this study, we are being asked to accept that a difference in telomere length is firstly explained by a specific dietary behaviour – in this case a Mediterranean diet – and second, that such a difference is predictive of future health benefits. Both such assumptions come with health warnings.

“Firstly, rather than the dietary behaviour, as this is an observational study, many other aspects of the nurses lifestyle who ate such a diet may explain the telomere length being greater. Secondly, telomere length, whilst of interest, is a relatively new risk marker and whether it meaningfully predicts longer term health consequences in way that give true signals for future health is still under debate.

“I would therefore suggest the findings in this study are of interest but by no means conclusive. It would be nice to see such data replicated in a clinical trial with proper interventions on diet or other interventions, and only randomisation can limit bias.”

Gaynor Bussell, Dietitian and Public Health Nutritionist, said:

“The Mediterranean diet has certainly had plenty of coverage recently and all the research seems very positive. This is yet another positive story this time with regard to telomere length, which is associated with life length.

“However, many health experts have been frustrated by the fact that it is very hard to define what the Mediterranean diet actually is. In this study, the researchers seem to have captured certain elements of what is perceived to be the Mediterranean diet and have suggested that it is all these elements coming together that make it such a healthy diet.  This still leaves the definition of this diet still a little vague and therefore hard to reproduce so that similar research can be replicated to show that such a diet really does have a number of health benefits and to show what in the diet actually leads to  these benefits

“It does show, however,  what many diet experts have said for a while, that there are no ‘superfoods’ and maybe not even foods that are good or bad, but it’s the complete diet made up of a number of different foods (and not too much of any) that can offer a health advantage.”

‘Mediterranean diet and telomere length in Nurses’ Health Study: population based cohort study’ by Crous-Bou et al. published in The BMJ on Tuesday 2^nd December. 

Declared interests

None declared