Diets with high glycemic index tied to elevated CVD, mortality risk
Eating a diet with a high glycemic index was associated with elevated risk for CVD and mortality, according to new data from the PURE study published in The New England Journal of Medicine.
According to the study background, diets with a high glycemic index feature poor-quality carbohydrates such as those found in white bread, rice and potatoes, whereas diets with a low glycemic index feature good-quality carbohydrates such as those found in fruits, vegetables, beans, legumes and intact whole grains.
“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,” David J.A. Jenkins, MD, PhD, professor of nutritional sciences and medicine at the University of Toronto’s Temerty Faculty of Medicine and a scientist in the Li Ka Shing Knowledge Institute of St. Michael’s Hospital, Unity Health Toronto, said in a press release.
The researchers analyzed 137,851 participants from five continents who were followed for a median of 9.5 years. Through food frequency questionnaires, the researchers calculated dietary intake for each participant and determined the glycemic index and glycemic load of each participant’s diet based on consumption of seven categories of carbohydrate foods.
The primary outcome was all-cause mortality or a major CV event, defined as CV death, nonfatal MI, stroke or HF.
Compared with those in the quintile with the lowest glycemic index, those in the quintile with the highest glycemic index had elevated risk for the primary outcome, regardless of whether the individual had preexisting CVD (adjusted HR = 1.51; 95% CI, 1.25-1.82) or not (aHR = 1.21; 95% CI, 1.11-1.34).
High glycemic index was also associated with elevated risk for all-cause mortality, CV death, major CV events and stroke, the researchers wrote.
High glycemic load compared with low glycemic load was associated with increased risk for the primary outcome in those with preexisting CVD, but not in those with no prior CVD, Jenkins and colleagues wrote.
“The present data, along with prior publications from the PURE and several other studies, emphasize that consumption of poor quality of carbohydrates are likely to be more adverse than the consumption of most fats in the diet,” Salim Yusuf, MD, DPhil, FRCP, FACC, principal investigator of the PURE study, executive director of the Population Research Health Institute and professor of medicine at McMaster University in Hamilton, Ontario, Canada, said in the release. “This calls for a fundamental shift in our thinking of what types of diet are likely to be harmful and what types neutral or beneficial.”