Illinois Tech Study Shows Red Raspberries Could Help Reduce Health Risks for People with Prediabetes

For millions of adults in the United States who have prediabetes, regularly eating a couple of handfuls of red raspberries could help reduce their risk of progressing to more serious health conditions, including type 2 diabetes.

That’s according to the results of a new study published in Obesity by a research team led by Britt Burton-Freeman, director of the Center for Nutrition Research at Illinois Institute of Technology’s Institute for Food Safety and Health. The team’s findings point toward specific information that medical professionals can use to help their patients with prediabetes and insulin resistance make dietary changes to improve their health.

“We’re focused on diet as a strategy to prevent transition to disease, and we’re targeting the people who are at risk,” says Burton-Freeman. “Ideally, we can identify such people very early on, so it’s possible to reverse the trajectory toward a disease diagnosis.”

The number of people at risk for diabetes in the U.S. is large. A report put out by the Centers for Disease Control and Prevention estimated that 84.1 million, or about one-third, of adults in the country had prediabetes in 2015.

Burton-Freeman and her colleagues have been investigating bioactive compounds in fruits and vegetables that are linked to a reduced risk of diabetes and cardiovascular disease. The compounds in berries can influence blood glucose levels and the progression of diabetes, she says, while compounds in other plants they’ve studied impact vascular reactivity, which is related to blood pressure regulation and hypertension. The research team’s clinical trials are designed to pinpoint the metabolic effects that the compounds have on human physiology.

This most recent study, titled “Attenuation of Postmeal Metabolic Indices with Red Raspberries in Individuals at Risk for Diabetes: A Randomized Controlled Trial,” focused on a group of people at risk for diabetes who were overweight or obese and had prediabetes and insulin resistance. The study also included a metabolically healthy control group. All were given breakfasts with zero, one, or two cups of raspberries on different days, and their glucose and insulin levels were tested during the 24 hours following the meals. When the at-risk group ate the meals with two cups of raspberries, they needed less insulin to control their glucose levels than when they ate no raspberries, indicating the potential benefits of adding raspberries to their diet.

Following up on these findings, Burton-Freeman notes that these data support conducting a clinical study to measure the metabolic impact of raspberries over a longer duration of four weeks rather than 24 hours. Currently, her group is engaged in a study on the metabolic effects of raspberry consumption on cognitive function.

Looking ahead, she and her team plan to investigate how a person’s progression toward disease—for example, someone newly identified with prediabetes versus someone who has been struggling with climbing glucose and declining insulin levels over a few years —may impact the effectiveness of a specific dietary intervention.

“We’re hoping our research can be actionable,” Burton-Freeman says, “and help people improve their diets to reduce the risk for diabetes and cardiovascular disease.”