Some individuals particularly those with health conditions are conscientious about consuming food that are high in the glycemic index such as potatoes and white bread because these are known to cause blood sugar levels to rise rapidly.
It is believed that low glycemic diets can help improve blood sugar levels and insulin sensitivity, but findings of a new study did not find evidence for such benefits.
For the study published in JAMA on Dec.17, Frank Sacks, from the Department of Nutrition, Harvard School of Public Health, and colleagues examined the effects of foods that fall low on the glycemic index on risk factors for cardiovascular disease and diabetes by assigning 163 overweight adult with elevated blood pressure to adopt one of four heart-healthy diets for five weeks at a time.
Each of these diets were based on the Dietary Approaches to Stop Hypertension (DASH) diet, which helps treat and prevent hypertension by reducing a person's salt intake and includes food that help lower blood pressure.
All diets assigned to the participants included ample amount of fruit, vegetables and low-fat dairies and are low in saturated and total fat. The diets, however, differ in a way that they were either low or high in carbohydrates and either low or high in the glycemic index.
The results revealed that obese and overweight adults do not have to worry much where the food they eat falls on the glycemic index. The researchers found that the participants on low glycemic diets did not show improvements in their insulin sensitivity, blood pressure and cholesterol levels suggesting that using glycemic index when selecting specific food may not improve insulin resistance or cardiovascular risk factors.
"In the context of an overall DASH-type diet, using glycemic index to select specific foods may not improve cardiovascular risk factors or insulin resistance," the researchers wrote.
The researchers, however, noted that their study did not look at the effects of the glycemic index in the typical U.S. diet. They did not also examine its impact on weight loss and on individuals with type 2 diabetes. Current evidence suggests that a low glycemic diet could help diabetics and people who want to lose weight.
"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," Sacks said. "Our findings demonstrated that using glycemic index to select specific foods did not improve LDL cholesterol, HDL cholesterol, triglycerides, blood pressure or insulin resistance."