Endocrinologists typically recommending carbohydrate restriction is for their patients with diabetes to help maintain glycemia within a normal range, explains Yang Hu, ScD. “Although previous dietary intervention studies on patients with diabetes found a diet low in carbohydrate might promote weight loss and improve cardiovascular risk factors in the short term, there was a lack of evidence from randomized controlled trials and prospective cohort studies that assess the health benefits of long-term adherence to a low-carbohydrate diet pattern,” Hu says.
In a study published in Diabetes Care, Hu and colleagues sought to address this knowledge gap by examining the health effects of multiple versions of low-carbohydrate diets in relation to mortality in a population of patients with T2D who were followed up for more than 30 years.
Assessing Macronutrient Quality of Low-Carb Diets
The study team aimed to understand the association of adhering to an overall low-carbohydrate diet on total and cause-specific mortality among participants with T2D. “We evaluated the associations of several versions of low-carbohydrate diet, with an emphasis on different macronutrients quality, because we were curious if a low-carbohydrate diet with high animal fat/protein or high plant-sourced fat/protein contents would have similar associations with mortality,” Dr. Hu says.
Study participants were selected from the Nurses’ Health Study and Health Professionals Follow-up Study. Patients with T2D (N=10,101; 139,407 person- years) were assessed from the time of diagnosis until the end of the study period or deaths. During follow-up, the study team reported 4,595 deaths; 881 were attributed to cancer and 1,389 to cardiovascular disease. Diet information was evaluated using validated food-frequency questionnaires. “Based on the percentage of energy from carbohydrate, fat, and protein, the low-carbohydrate diet scores were constructed to reflect the adherence to low-carbohydrate diets,” Hu notes. “We used statistical models to evaluate the associations between these scores and mortality.”
Adopting Concurrent Healthy Lifestyle Behaviors Has Added Benefits
Hu and colleagues observed that switching to and maintaining a plant-based low-carbohydrate diet after a diagnosis of diabetes may confer long-term health benefits to patients. “Patients with diabetes might gain additional health benefits by adopting concurrent healthy lifestyle behaviors after diagnosis, including not smoking, moderate alcohol consumption, and regular moderate-to-vigorous physical activity,” Dr. Hu points out. “This means that combining a healthy version of low-carbohydrate diet with these healthy lifestyle factors may be more effective in improving the health of patients with diabetes, than adhering to the diet alone (Figure).”
Among people with established T2D, a low-carbohydrate diet may have differential health effects on mortality depending on its composition, according to the study. “Our analysis suggests that only low-carbohydrate diets with an emphasis on plantsourced fat, plant-based protein, and high-quality carbohydrates, such as those from whole grains, fruits, and vegetables, were associated with significantly lower mortality,” Hu says. He adds that clinicians may find the results of the study useful when providing dietary recommendations to their patients with diabetes.
It is not clear, however, whether healthy low-carbohydrate diets could help prevent the development of diabetes in the general population is still not clear, according to Hu and colleagues. “For future research, we’re interested in evaluating the associations between long-term adherence to low-carbohydrate diets and weight change, because the low-carbohydrate diet is often promoted as an effective dietary pattern for weight loss,” Hu says. “Our current study may provide insights for future precision nutrition research that can help elucidate the mechanisms underlying the health benefits of a low-carbohydrate diet since animal- and plantsourced low-carbohydrate diets might result in differential responses in circulating metabolomics and gut microbiome.”
