New research published in the Journal of the American Medical Association (JAMA), demonstrates that the glycemic index, the basis of many popular diets, may ultimately not be of high importance to those who already follow a healthful diet.
The study, funded by the National Institutes of Health, found that eating a low glycemic index (GI) diet does not lower blood pressure, improve blood cholesterol levels or increase insulin sensitivity, all of which are known risk factors for cardiovascular disease and diabetes.
Researchers from Johns Hopkins and Brigham’s and Women’s Hospital studied the cardio-metabolic effects of four different diets that varied in GI (either high or low) and carbohydrate content (either high or low) in 163 overweight, hypertensive adults. All meals, snacks and beverages were provided to study participants in accordance with a healthful DASH (Dietary Approaches to Stop Hypertension)-type dietary pattern. Potatoes, which have often been classified as a high GI food to be avoided, were included in both the low and high GI diets used in the study. At the end of the 5-week intervention period, those following the low GI diets saw no greater improvements in blood pressure, insulin sensitivity or blood lipid levels than those following the high GI diets.
“Proponents of the glycemic index claim that a low-GI diet can reduce risk factors for diabetes and cardiovascular disease,” explained Katherine Beals, PhD, RD, FACSM, consultant to the United States Potato Board and expert on carbohydrate metabolism. “But, these results showed that, in the context of a healthful diet, GI doesn’t matter. The low GI diet was no more effective than the high GI diet for improving insulin sensitivity, HDL or LDL cholesterol levels or systolic blood pressure.”
So, the JAMA study is more good news for potatoes, adding to a growing pool of research that demonstrates the positive role potatoes play in a healthy diet. Anyone who craves the satisfaction of wholesome and healthy meal options can take heart that one medium-size (5.3 ounce) skin-on potato contains just 110 calories per serving, boasts more potassium (620mg) than a banana, provides almost half the daily value of vitamin C (45 percent), and contains no fat, sodium or cholesterol.