Diet counteracts genetic stroke risk

World Health Matters by Gary Finnegan – Spain – A gene variant strongly associated with the development of type 2 diabetes appears to interact with a Mediterranean diet pattern to prevent stroke, according to a new study.

The Mediterranean diet features olive oil, fish, complex carbohydrates and nuts, and has long been associated with longevity and good health.

Researchers at the CIBER Fisiopatología de la Obesidad y Nutriciόn in Spain, in collaboration with the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University, have been examining the roles of genetics and diet in cardiovascular benefits seen in the Mediterranean diet.

A randomised, controlled trial enrolled more than 7,000 men and women in Spain and assigned them either to a Mediterranean or low-fat control diet. Participants were then monitored for cardiovascular disease, stroke and heart attack for almost five years.

“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 senior author Dr José M. Ordovás, director of the Nutrition and Genomics Laboratory at Tufts University.

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% of participants in the study were homozygous carriers, meaning they carried two copies of the gene variant and had an increased risk of disease.

“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,” explained Ordovás.

“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 results were strongest in subjects who stuck closely to the Mediterranean diet, according to Dr Dolores Corella of the CIBER Fisiopatologia de la Obesidad y Nutriciόn.

“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,” she said.