A study published in JAMA reveals low glycemic index of dietary carbohydrate, did not have improvements in insulin sensitivity or cardiovascular benefits.

Foods that have similar carbohydrate content can differ in the amount they raise blood glucose, a property called the glycemic index. Frank M. Sacks, M.D (Brigham and Women's Hospital and Harvard Medical School, Boston) and colleagues conducted a trial in which 163 overweight adults with pre-hypertension or stage 1 hypertension were given 4 different complete diets that contained all of their meals, snacks, and calorie-containing beverages, each for 5 weeks; and completed at least 2 study diets. The diets were:

(1) a high–glycemic index (65% on the glucose scale), high-carbohydrate diet (58% energy)
(2) a low–glycemic index (40%), high-carbohydrate diet
(3) a high–glycemic index, low-carbohydrate diet (40% energy)
(4) a low–glycemic index, low-carbohydrate diet

Each diet was based on a healthful DASH - type diet. In the 5-week controlled feeding study, researchers found that diets with low glycemic index of dietary carbohydrate, compared with high glycemic index of dietary carbohydrate, did not result in improvements in insulin sensitivity, lipid levels, or systolic blood pressure. 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.

Read More