A study was conducted with participants from five different countries to analyze the relationship between glycemic index and cardiovascular disease(CVD). Glycemic index being how much 50g of carbohydrates raise blood sugar, depending on the type of food.
Diets consisting of low glycemic foods have previously been thought to have a correlation with lower postprandial glucose levels, lower serum cholesterol levels, and lower blood pressure; all of these combining to reduce the risk of both diabetes and CVD. However, there is not enough data to confirm this association between foods with low glycemic levels and CVD risk. In addition, all of the research conducted thus far has been in only Western countries, which lowers the generalizability of the studies conducted on this topic thus far.
The current study, conducted by the Prospective Urban Rural Epidemiology(PURE), analyzed participants on the “cardiovascular impact of glycemic index and glycemic load.” The study includes almost 138,000 participants from four high-income countries, eleven middle-income countries, and five low income countries, and are all between 35 and 70 years old. Participants answered a questionnaire with 3,200 different food items, with the ‘bread scale’ (white bread = 100) being used to define glycemic index. Glycemic load was calculated by multiplying the glycemic index by the average net carbohydrate intake and dividing it by 100. The “primary outcome of the study” was a combination of cardiovascular events or any cause of death. Out of the participants in the study, Participants in China, Africa, and Southeast Asia consumed foods with the greatest glycemic index.
Participants followed up in a median of 9.5 years, and “the primary outcome” occurred in about 14,000 participants, death occurred in almost 8,800 participants, and at least one major cardiovascular event occurred in almost 8,300 participants. A positive correlation was found between “the primary outcome” and high glycemic index in participants both with and without pre-existing CVD. An association was also found between an increased risk of death and a higher glycemic index. For solely high glycemic load, a positive correlation was only found for “major cardiovascular events and death in those with pre-existing CVD.”
One weakness of the study is because the foods were grouped into categories based on glycemic index, yet there is high variability in foods from around the world, which limits the accuracy of the value of each food item. An additional limitation was that diet changes were not accounted for, which could have affected the outcome. A strength of this study is that it is highly generalizable, with participants from around the world, with varying wealth statuses and diets. The results showed that patients who consume lower glycemic index and lower glycemic load are at a lower risk of death and cardiovascular disease. It is recommended that clinicians show their patients healthy alternatives to their diet choice in order to decrease the risk of CVD.
