Researchers have claimed that a gene variant, strongly linked with the development of type 2 diabetes, seems to interact with Mediterranean diet - featuring olive oil, fish, complex carbohydrates and nuts - to prevent stroke.
Researchers from the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University and from the CIBER Fisiopatologia de la Obesidad y Nutricion in Spain set out to investigate whether genetics contribute to the cardiovascular benefits seen in the Prevencion con Dieta Mediterranea (PREDIMED) trial.
Based in Spain, the randomized, controlled trial enrolled more than 7,000 men and women assigned to either a Mediterranean or low fat control diet and monitored them for cardiovascular disease, stroke and heart attack for almost five years.
Senior author Jose M. Ordovas, Ph.D., director of the Nutrition and Genomics Laboratory at the USDA HNRCA at Tufts University, said that the PREDIMED study design provided them with stronger results than we have ever had before.
He said that 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.
Led by Ordovas and corresponding author Dolores Corella, Ph.D., of the CIBER Fisiopatologia de la Obesidad y Nutricion , the researchers focused on a variant in the Transcription Factor 7-Like 2 (TCF7L2) gene, which has been implicated in glucose metabolism but its relationship to cardiovascular disease risk has been uncertain.
About 14 percent of the PREDIMED participants were homozygous carriers, meaning they carried two copies of the gene variant and had an increased risk of disease.
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Ordovas said that being on the Mediterranean diet reduced the number of strokes in people with two copies of the variant. 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.
He said that 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.
To find out how closely the PREDIMED participants adhered to the Mediterranean diet prior to the trial, the authors examined food frequency questionnaires.
Corella said that the team again saw that the Mediterranean diet appeared to compensate for genetic influence.
She said that if adherence to the diet was high, having two copies of the gene variant had no significant influence on fasting glucose levels.
She added that the same was true for three common measures of cardiovascular disease risk: total blood cholesterol, low density lipoprotein and triglycerides.
The results have been published online in Diabetes Care.