The glycemic index (GI) ranks carbohydrate-containing foods according to how quickly they affect blood sugar levels. High GI foods cause a rapid increase in blood sugar and include white bread, white rice, potatoes, and sweets. Low GI foods are digested more slowly and gradually raise blood sugar; they include some fruits and vegetables such as apples, oranges, broccoli, and leafy greens, pulses such as chickpeas, lentils, and kidney beans, and whole grains such as brown rice and oats. Meat, poultry, and fish do not have a GI rating because they do not contain carbohydrates.
Observational studies have previously indicated that high GI diets are associated with increased risks of cardiovascular disease2 and type 2 diabetes.3 This randomized controlled study assessed the potential benefit of a low GI diet on body mass index (BMI), waist circumference, hip circumference, and waist-to-hip ratio in patients with coronary artery disease.
Between 2016 and 2019, the study randomly allocated 160 patients aged 38 to 76 years old to three months of either a low GI diet or routine diet. Both groups continued to receive standard therapies for coronary artery disease. Patients in the low GI group were advised to consume low GI foods and exclude high GI foods while continuing their usual consumption of protein and fat.
The routine diet group was advised to consume the recommended diet for coronary artery disease which limits fat and some proteins such as whole milk, cheese, meat, egg yolks, and fried foods. Dietary adherence was assessed with a food frequency questionnaire. Anthropometric indices were measured at baseline and three months.