Consuming More Whole Grains Could Lower Diabetes Risk

Kim Braun, PhD

New research suggests consuming more whole grains could lower a person’s risk of developing type 2 diabetes.

Presented at Nutrition Live Online 2020, a virtual conference hosted by the American Society for Nutrition (ASN), results of the analysis indicate substituting calories with high quality carbohydrates, such as those in whole grains, could reduce risk of developing type 2 diabetes while substitution with low quality carbohydrates, such as those from refined grains, sugary foods, and potatoes, was found to increase risk.

"These results highlight the importance of distinguishing between carbohydrates from high- and low- quality sources when examining diabetes risk," said lead investigator Kim Braun, PhD, a postdoctoral research fellow from Erasmus University Medical Center and Harvard T.H. Chan School of Public Health, in a statement. "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."

With previous research indicating carbohydrate intake was associated with higher risk of type 2 diabetes, Braun and a team of colleagues sought to determine the specific effects of high and low quality carbohydrates on this association. Additionally, investigators hoped to evaluate whether overall macronutrient composition could have an impact on this effect.

For the purpose of analysis, investigators designed the current study to assess associations of isocalorically substituting high quality carbohydrates and low quality carbohydrates with other macronutrients on type 2 diabetes risk. Using the Nurses’ Health Study, Nurses’ Health Study 2, and the Health Professionals Follow-up Study, investigators identified cohorts of 69,949 women, 90,239 women, and 40,539, respectively.

Of note, dietary data of the participants form these 3 studies was recorded every 2-4 years using food frequency questionnaires. Investigators defined low quality carbohydrates as the percent of energy (E%) from carbohydrates from refined grains, sugary foods, and potatoes while high quality carbohydrates was defined as E% from carbohydrates from whole grains.

Over 4,389,996 years of follow-up, a total of 11,872 cases of type 2 diabetes was identified for analysis. Results of a pooled multi-variable adjusted model indicated substituting 5E% from saturated fat with 5E% from low quality carbohydrates was associated with a higher risk of type 2 diabetes (HR, 1.05; 95% CI, 1.00-1.09). Conversely, substation with high quality carbohydrates was associated with a lower risk of type 2 diabetes (HR, 0.93; 95% CI, 0.87-0.99).

Investigators highlighted isocaloric substitution of other macronutrients was not associated with an increase in risk of type 2 diabetes. However, further analysis revealed isocaloric substitution of high quality carbohydrates was associated with a lower risk when the replaced nutrient was monounsaturated fat (HR, 0.88; 95% CI, 0.83-0.94), polyunsaturated fat (HR, 0.92; 95% CI, 0.86-0.98), trans fat (HR, 0.90; 95% CI, 0.85-0.97), animal protein (HR, 0.88; 95% CI, 0.83-0.93), and vegetable protein (HR, 0.90; 95% CI, 0.84-0.96).

This study, “Carbohydrate Quantity and Quality and Risk of Type 2 Diabetes: Results from Three Large Prospective US Cohorts,” was presented at Nutrition Live Online 2020.