A global study focused on people living in five continents found that a diet high in poor quality carbohydrates leads to a higher risk of heart attacks, strokes, and death. The findings of the study were published in the New England Journal of Medicine. The higher risks of a diet high in poor quality carbohydrates, called a high glycemic diet, were similar to whether people had previous cardiovascular disease or not.
A total of 137,851 people aged 35 to 70 years old were followed for a median of 9.5 years through the Population Urban and Rural Epidemiology (PURE) study run by the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences. The research team used food questionnaires to measure the long-term dietary intake of participants and estimate the glycemic index (the ranking of food based on their effect on blood sugar levels) and glycemic load (the number of carbohydrates in food times its glycemic index) of diets. There were 8,780 deaths and 8,252 major cardiovascular events recorded among the participants during the follow-up period.
The investigators categorised dietary intake of carbohydrates depending on whether specific types of carbohydrates increased blood sugars more than others (high glycemic index) and compared this index to the occurrence of cardiovascular disease or death.
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Those people consuming a diet in the highest 20% of the glycemic index was 50% more likely to have a cardiovascular attack, stroke, or death if they had a pre-existing heart condition, or 20% more likely to have an event if they did not have a pre-existing condition. These risks were also higher among those people who were obese.
“I have been studying the impact of high glycemic diets for many decades and this study ratifies that the consumption of high amounts of poor quality, carbohydrates is an issue worldwide,” said first author David Jenkins, professor of nutritional sciences and medicine at the University of Toronto’s Temerty Faculty of Medicine, who is also a scientist in the Li Ka Shing Knowledge Institute of St. Michael’s Hospital, Unity Health Toronto. “PURE study papers have already indicated that not all carbohydrate foods are the same. Diets high in poor quality carbohydrates are associated with reduced longevity, while diets rich in high-quality carbohydrates such as fruit, vegetables, and legumes have beneficial effects,” he said.