Glycemic Index, Glycemic Load, and Cardiovascular Disease and Mortality
There are fewer data to provide clarification on the association between a low glycemic index diet and cardiovascular risk reduction with more research data from high-income western populations. There is less data for non-western countries with low or middle incomes. The author D.J.A. Jenkins and colleague (2021) published a research paper in the New England Journal of Medicine under the title “Glycemic Index, Glycemic Load, and Cardiovascular Disease and Mortality”. The summary of the findings is below:
Objectives:
To study the relationship between the glycemic index and cardiovascular disease and all-cause mortality.
Method:
137,851 participants between the age of 35-70 years were included in the study from 5 continents. The countries included 4 high-income countries (Canada, Sweden, Saudi Arabia, and the United Arab Emirates), 11 middle-income countries (Argentina, Brazil, Chile, China, Colombia, Iran, Malaysia, Palestinian territory, Poland, South Africa, and Turkey), and 5 low-income countries (Bangladesh, India, Pakistan, Tanzania, and Zimbabwe). Country-specific food-frequency questionnaires were used to determine dietary intake. On the basis of consumption of seven categories of carbohydrate foods, glycemic index and glycemic load were estimated. Multivariable Cox frailty models were used to calculate hazard ratios. The primary result was a composite of a major cardiovascular event or death from any cause.
Findings:
China, followed by Africa and Southeast Asia had highest consumption of high glycemic index food, whereas, South Asians consumed high glycemic load food.
The study concludes that across multiple countries and geographic and economic regions, high glycemic index diets were associated with a higher risk of cardiovascular disease and death as compare to diets with a low glycemic index. As per the investigator’s expectations, persons with a high BMI are at increased risk for cardiovascular disease, diabetes, and certain cancer. Additionally, with increasing BMI the overall postprandial glycemic response to diet increases. Low glycemic index diets have been associated with reduced incidence of cardiovascular disease and diabetes. Although the effects are less marked, consumption of high glycemic load food had similar effect on cardiovascular disease.
Limitation:
Investigators acknowledge several limitations as follows: firstly, categorization of carbohydrate foods may have resulted in less precision in calculations as compared to the method of calculating values for individual foods. Secondly, the findings might not be uniform due inclusion of many different populations. Third, due to a smaller number of participants belonging to a specific region or country, the attempt to study how different regions and countries might get affected differently by diets with a high glycemic index didn’t succeed. Fourth, investigators could not correct for measurement errors in covariates. Lastly, the dependence on one baseline measure of dietary intake might not reflect current patterns in the various countries.
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