Mediterranean Diet And Genetics
August 13, 2013

Mediterranean Diet Offsets Genetic Stroke Risk

Brett Smith for - Your Universe Online

Fad diets come and go, but they may be be doing more to our bodies than simply affecting our weight. According to a new study in the American Diabetes Association's journal Diabetes Care, the so-called Mediterranean diet of olive oil, fish, complex carbohydrates and nuts can result in a lower likelihood of stroke, even among individuals who have a genetic predisposition to higher stroke risk.

Study researchers set out to examine potential cardiovascular benefits of the food regimen in the Spain-based Prevencion con Dieta Mediterranea (PREDIMED) trial.

"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," said study author Jose M. Ordovas, director of the Nutrition and Genomics Laboratory at the USDA’s Human Nutrition Research Center on Aging at Tufts University.

"The PREDIMED study design provides us with stronger results than we have ever had before,” Ordovas said. “With the ability to analyze the relationship between diet, genetics and life-threatening cardiac events, we can begin to think seriously about developing genetic tests to identify people who may reduce their risk for chronic disease, or even prevent it, by making meaningful changes to the way they eat."

The randomized PREDIMED trial included over 7,000 participants who were assigned to either a Mediterranean or low-fat control diet. Participants were then monitored for cardiovascular disease, stroke and heart attack for almost five years.

In the study, researchers focused their attention on a variant in the TCF7L2 gene, which has been linked to glucose metabolism and suspected of having an effect on cardiovascular disease. Approximately 14 percent of the PREDIMED participants carried two copies of the gene variant, potentially translating into an increased risk of disease.

"Being on the Mediterranean diet reduced the number of strokes in people with two copies of the variant Ordovas explained. “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.

"The results were quite different in the control group following the low fat control diet, where homozygous carriers were almost three times as likely to have a stroke compared to people with one or no copies of the gene variant,” he said.

The researchers also looked at PREDIMED surveys to examine any potential confounding factors associated with participants’ diet history.

"Again, we saw that the Mediterranean diet appeared to compensate for genetic influence," said co-author Dolores Corella, a scientist in the Genetic and Molecular Epidemiology Unit at the University of Valencia in Spain. "If adherence to the diet was high, having two copies of the gene variant had no significant influence on fasting glucose levels. The same was true for three common measures of cardiovascular disease risk: total blood cholesterol, low density lipoprotein and triglycerides. Conversely, these risk factors were considerably higher in homozygous carriers with low adherence to the diet."

Study authors said future research should be focused on identifying the mechanism behind the lowered risk.