Eating more whole-grain foods might lower the risk of developing type 2 diabetes, says a new report. The finding was delivered at a “virtual conference” called Nutrition Live Online 2020 that was hosted by the American Society for Nutrition.
The possible relationship between carbohydrate consumption and type 2 diabetes has been a subject of research and debate for some time. Basically, the idea is that if carbs tend to cause weight gain and weight gain is a factor in the development of diabetes, then reducing carbohydrate consumption should be a good way to lower the risk of diabetes. But it’s not that simple. The American Diabetes Association has said carbohydrates are one of the essential food groups (along with protein and fat) and that it’s mostly processed foods, which tend to be rich in carbs while low in vitamins and fiber, that are to be eaten with caution. Also, foods with carbs can be rich in fiber, and fiber can help manage blood sugar.
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In the new report, the researchers noted that if previous studies had indicated that carbohydrate intake was associated with a higher risk of developing type 2 diabetes, it would be valuable to find out if there is a difference between consuming high-quality carbs and low-quality carbs. They also wondered if other macronutrients could play a role. According to one of the researchers, Shilpa N. Bhupathiraju, PhD, of the Harvard T.H. Chan School of Public Health, “Previous studies have examined associations between carbohydrate intake and type 2 diabetes risk. We wanted to specifically examine if the association between carbohydrate intake and type 2 diabetes risk differed by the quality of the carbohydrate and by the nutrient it replaced in the diet.”
The researchers assessed data collected from three studies: the Nurses’ Health Study, the Nurses’ Health Study II, and the Health Professionals Follow-Up Study. The number of participants was more than 200,000. Information on diet was collected from the subjects every two to four years by using food frequency questionnaires, and the follow-up period, collectively, totaled nearly four million years. The researchers found nearly 12,000 cases of type 2 diabetes.
While pointing out that when people adopt a low-fat diet, they usually replace fat with low-quality or refined carbohydrates, Dr. Bhupathiraju, along with her team, discovered that substituting 5% of energy from saturated fat with 5% of energy from low-quality carbs (refined grains, potatoes and high-sugar foods) was associated with a higher risk of type 2 diabetes. On the other hand, replacing 5% of energy from saturated fat with high-quality carbs (whole-grain bread, brown rice, barley, quinoa and rye) was associated with a lower risk. Substituting other macronutrients was not related to type 2 diabetes risk. However, when high-quality carbohydrates replaced polyunsaturated fat, trans fat, animal protein or vegetable protein, the risk of type 2 diabetes was lessened.
Dr. Bhupathiraju summed up the findings by noting, “When individuals consume a low-fat diet, the replacement nutrient is almost always low-quality or refined carbohydrates that our study shows to be associated with a higher risk for type 2 diabetes.” The new study, she said, shows that “the quality of carbohydrate matters.” Lead researcher Kim Braun, PhD, said, “These results highlight the importance of distinguishing between carbohydrates from high- and low-quality sources when examining diabetes risk. Conducting similar studies in people with various socio-economic backgrounds, ethnicities and age will provide insight into how applicable these findings are for other groups.”
High-quality carbohydrates are found mostly in whole-grain foods, which include brown rice, oatmeal, whole-wheat bread and pasta, buckwheat, rye, bulgur, quinoa and barley. These foods also tend to have have higher amounts of fiber as well as such important nutrients as iron, potassium, magnesium and vitamin B.