To get all the health benefits of low glycemic foods, Americans would have to double their consumption of beans and lentils — something most are unlikely to do.
A new study from Canada shows that eating just one serving per day of such foods may significantly lower levels of “bad cholesterol” along with the risk of developing heart disease. Yet most Americans and Canadians eat less than half a serving of low glycemic foods every day.
John Sievenpiper, who led a study at St. Michael’s Hospital in Toronto, says choosing low glycemic foods — such as beans, chickpeas, skim milk, apples, and fresh grapefruit — may lower harmful levels of LDL cholesterol by five percent. Such a reduction would in turn lower the risk of heart disease by five to six percent.
The dietary change would require only the consumption of a three-quarter cup serving of low glycemic foods also known as “pulses.” Such foods are digested slowly while displacing or otherwise reducing harmful levels of animal proteins and trans fats.
"We have a lot of room in our diets for increasing our pulse intake to derive the cardiovascular benefits," Sievenpiper said in a statement. "Pulses already play a role in many traditional cuisines, including Mediterranean and South Asian.”
Sievenpiper reviewed 26 high-quality clinical trials with a total of more than 1,000 study participants. Among his findings, men in the study experienced greater reductions in bad cholesterol than women, with some participants reporting initial stomach problems that dissipated during the course of the study.
Sievenpiper says men might have benefited the most from the dietary change, perhaps because they’d previously eaten less healthfully than the women in the study. Yet evidence for the health benefits of a low glycemic diet remains mixed, according to the Mayo Clinic. Aside from these recent findings on bad cholesterol, proponents of the diet claim a number of ailments from diabetes to heart disease may be ameliorated with improved food choices. But claims that the diet helps with weight loss remain largely unproven.
They “say that following a diet based on the glycemic index can help you choose foods that will result in weight loss and prevention of chronic diseases,” the Mayo Clinic says. "But scientific evidence supporting the role of the glycemic index diet in weight loss remains mixed — and you might be able to achieve the same health benefits by eating a healthy diet, maintaining a healthy weight and getting enough exercise.”
The University of Sydney in Australia maintains a comprehensive database ranking foods from the around the world along a glycemic food index of 1-100, with high glycemic foods such as instant white rice, brown rice, watermelon, and potatoes ranking 70 or higher. In the medium range are bananas, raw pineapple, raisins, and sweet corn.
Low glycemic foods such as kidney beans and raw carrots are ranked as 55 and lower on the scale.
Source: Sievenpiper J, Ha V, De Souza RJ, et al. Effect of dietary pulse intake on established therapeutic lipid targets for cardiovascular risk reduction: a systematic review and meta-analysis of randomized controlled trials. Canadian Medical Association Journal. 2014.