Low Glycemic Index (GI) diets not always beneficial for heart and diabetes points new study

The role played by Glycemic Index (GI), which is a measure of carbohydrate effect on levels of blood sugar, has been a much talked about topic during the last few years. Some diet experts proposed cutting down on foods with high GI (like white bread and potatoes) because they cause the insulin levels in the blood to spike up and replacing them by healthier carbs like whole grains and low-starch vegetables which have a lower GI.

The findings of a new study have pointed out that the glycemic index might not be too important for people already following a healthy diet.

Franck Sacks and his colleagues have, in a paper published in the JAMA, discussed in detail the results of a randomized 5-week feeding trial comparing 4 different diets in 163 overweight or obese adults. The diets were either high carb or low carb and were all based on previously established healthy patterns based on the DASH diet. The DASH diet includes high amounts of fruits, vegetables and low fat dairy products while being low on saturated and total fats.

Sacks mentioned that they did not see any significant benefit in those sticking to a low GI diet. “In the main comparison of interest, the low–GI, low-carb diet, when compared with the high–GI, high-carb diet, lowered triglycerides from 111 to 86 mg/dL but had no significant impact on insulin sensitivity, systolic blood pressure, LDL cholesterol, or HDL cholesterol. Unexpectedly, in a comparison of the low and high-GI diets within the high-carb group, insulin sensitivity was decreased and LDL was increased in the low-GI group.”

The authors cautioned that their trial did not attempt to “address the effect of glycemic index in a typical US diet.” They also warn that they did not study the effect of lowering GI in people who have type 2 diabetes or for weight loss. Current evidence suggests that a low GI diet may be helpful in these situations.

“A low G.I. diet may be more like the tortoise than the hare. It takes longer, but gets you there in the end,” said Dr. David Jenkins, a professor of nutrition at the University of Toronto. However, there are researchers who are doubting the findings of this study citing it did not take into account those diagnosed with Type II diabetes.