A new study published in JAMA, titled, “Effects of High vs Low Glycemic Index of Dietary Carbohydrate on Cardiovascular Disease Risk Factors and Insulin Sensitivity“ says that low glycemic diets do not necessarily improve insulin sensitivity, blood pressure or lipid levels hence, it does not improve the risk factors for cardiovascular disease and diabetes.
Nutritionists are always trying to assess the nutritional values of food and its carbohydrate percentage to understand which food items are healthier than others. High carbohydrate foods are defined by how much they can increase sugar levels in blood – known as ‘glycemic index’. Researchers from the Brigham and Women’s Hospital (BWH), located in Boston, and from the Johns Hopkins University (JHU) in Baltimore, assessed the effect of the glycemic index on cardiovascular disease (CVD) and diabetes.
Dr. Frank Sacks, the lead author of this study, said in a press release: “The study results were very surprising. We hypothesized that a low glycemic index would cause modest, though potentially important improvements in insulin sensitivity and CVD risk factors. Our findings demonstrated that using glycemic index to select specific foods did not improve LDL cholesterol, HDL cholesterol, triglycerides, blood pressure or insulin resistance.”
A randomized and controlled trial was conducted, with the participation of 163 overweight adults who completed one of four diets, each with different characteristics. Researchers measured some important aspects, such as insulin sensitivity, levels of low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides and systolic blood pressure. The researchers then observed what happened when the diet’s total carbohydrate content was high, with a DASH diet (Dietary Approaches to Stop Hypertension), and with a low carbohydrate diet.
Sacks concluded: “We studied diets that had a large contrast in glycemic index, while at the same time we controlled intake of total carbohydrates and other key nutrients, as well as maintained baseline body weight. We found that composing a healthful diet with low-glycemic index carbohydrate containing foods rather that high-glycemic index foods did not improve insulin sensitivity, HDL or LDL cholesterol levels or systolic blood pressure.” Additional studies are needed to know if low glycemic index diets are beneficial for diabetes and weight loss, as previous research has only shown inconsistent or inconclusive results.