A global study of people living on five continents has found that a diet high in poor-quality carbohydrates (called a high-glycemic diet) leads to a higher risk of heart attacks, strokes, and death.

David Jenkins

The analysis of data from the PURE study is the largest of a geographically and dietary diverse population on this issue, as previous studies have chiefly focused on high-income Western countries.

The New England Journal of Medicine published the findings on “glycemic index, glycemic load, and cardiovascular disease and mortality this week. The higher risks were similar whether people had previous cardiovascular disease or not. Risks were higher among those who are obese.

“This study ratifies that the consumption of high amounts of poor-quality carbohydrates is an issue worldwide,” said the NEJM paper’s first author, David Jenkins, a scientist at the Li Ka Shing Knowledge Institute of St. Michael’s Hospital, a professor at the University of Toronto, and an associate senior scientist at PHRI.

Mahshid Dehghan

“Among a diverse population, a diet low in both its glycemic index and load has a lower risk of cardiovascular disease and death,” said PHRI’s Mahshid Dehghan, a co-investigator and co-author of the NEJM paper. (Glycemic index is a measure of carbohydrate availability, digestibility and absorption.)

White bread, rice, and potatoes have a high glycemic index. Most fruits, vegetables, beans, and intact whole grains have a low glycemic index.

Refined grains and CVD

Another paper Mahshid Dehghan coauthored this month – this time with first author S. Swaminathan of St. John’s Research Institute, India – and published in the British Medical Journal, looked at associations of cereal grains intake with cardiovascular disease and mortality across 21 countries in the PURE study.

This study showed that higher intake of refined grains was associated with higher risk of total mortality and major cardiovascular events. “Refined grains” were defined as low-fiber wheat grain products or flours modified to remove the bran and germ, including white bread, pasta/noodles, breakfast cereals, crackers, and bakery products/desserts containing refined grains.

Conclusions (and policy implications) of these analyses of PURE dietary data are to encourage populations to reduce the quantity and improve the quality of carbohydrates they consume in order to have better health outcomes.

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