Mediterranean diet reduces diabetes risk

Medical Tribune August 2008 SFXV
David Brill

Following a Mediterranean diet – known to lower cardiovascular risk – can also reduce the chance of developing diabetes, Spanish researchers have shown.

The study, which was published in the British Medical Journal, followed 13,380 university graduates over a median period of 4.4 years and used questionnaires to rank their adherence to the diet on a scale of one to nine.

“Those who were highly adherent to this traditional dietary pattern exhibited a very low rate [of diabetes] and an impressive magnitude in the relative risk reduction of 83 percent,” said lead researcher Miguel Martinez-Gonzalez, Professor of epidemiology at the University of Navarra.

Interestingly, he added, people who adhered most closely to the diet were typically older with a higher prevalence of hypertension, smoking history and other risk factors for diabetes. The incidence among this group would therefore have been expected to be high.

“This may mean that the Mediterranean diet is highly protective against diabetes,” he said, but added that only 33 new cases were observed – a small number relative to the size of the study.

“This is fortunate for our participants indeed but this is a major limitation. We need further evidence from larger cohorts and trials,” he said.

The traditional Mediterranean diet comprises high amounts of olive oil, fruit, vegetables, nuts and fish, and relatively low amounts of meat and dairy products. The health benefits of the diet have been shown in various studies, including a randomized trial which demonstrated a beneficial effect on cardiovascular risk factors. [Ann Intern Med 2006 Jul 4;145(1):1-11]

Dr. Warren Lee, former Chairman of the Diabetic Society of Singapore, said that the study was interesting and comprised good quality data.

“I would certainly say this reinforces the old chestnut that one should take more fruit and vegetables and emphasize less on the meat,” he said.

It remains unclear at what point of adherence to the diet the benefits begin to accrue, added Lee, who is a pediatric endocrinologist in private practice and a senior consultant at KK Women’s and Children’s Hospital.

"This study was not able to show a threshold effect because it was designed to show that there was an effect in a relatively homogenous population of people who ate either more than the mean or less than the mean of certain foods.

“However it was heartening that a two point increase in a nine point score was able to reduce the incidence rate ratio – a measure of relative risk – by 35 percent, and that even those in the moderate adherence group had a significant benefit. This suggests that people trying to adhere to a healthy diet will be better off than those who do not even try,” he said.

Lee noted that the diet in Spain is rather different to that in Singapore, where food is frequently cooked using palm oil or pork lard rather than olive oil.

“Perhaps the next step is to see how we can incorporate elements of this diet into our food choices,” he concluded.