Claims for the health benefits of
the typically Mediterranean diet high in olive oil, fish, and complex
carbohydrates are common, if hard to substantiate.
Previous studies associated the
TCF7L2 gene with regulation of blood sugar and pegged it as a diabetes risk
gene. It has also been more loosely implicated in regulating lipid (fat) levels
and in the development of cardiovascular disease. Results from a new large,
randomised controlled study show that diet can affect these genetic
'Our study is the first to identify a gene-diet interaction affecting
stroke in a nutrition intervention trial carried out over a number of years in
thousands of men and women', remarked Professor José OrdovÃ¡s, director of the Nutrition
and Genomics Laboratory at Tufts University, USA,
who led the study.
The study was part of the wider PREDIMED trial launched in 2003 to investigate cardiovascular risk and nutrition in
Spain. Over 7,000 participants were screened for the TCF7L2 variant and
answered food questionnaires before and during the five-year study.
Results showed those carrying two
copies of the genetic variant had raised levels of fasting glucose and lipids
in their blood, were at an increased risk of developing type 2 diabetes, and
also at an increased risk of stroke. Further investigation showed that these associations
were affected by the kind of diet participants adhered to.
'Being on the Mediterranean diet reduced the number of
strokes in people with two copies of the variant', said Professor OrdovÃ¡s. 'The food they ate appeared to
eliminate any increased stroke
susceptibility, putting put them on an even playing field with people with one
or no copies of the variant'.
In contrast participants in a control group on a low fat diet carrying two copies of the genetic variant were three times
more likely to have a stroke compared to people with one or no copies of the
genetic variant on the same diet.
The researchers suggest that components of the
Mediterranean diet, such as the antioxidants in olive oil, may overcome
genetic risk factors.
some of the more negative aspects you have in your diet to include some of
these components, and you can compensate for your risk', Professor OrdovÃ¡s told Fox News.
Professor Keith Ayoob from the Albert Einstein College of Medicine, USA, who was
not involved in the study, also supports the potential health benefits of the
Mediterranean diet, remarking to MedPage Today that 'this is certainly a great start and this is the diet that's got
the most leverage behind it because it has the most research'.
The study was published in the journal Diabetes