According to a new study, strawberry and cranberry polyphenols improve insulin sensitivity and reduce the risk of type 2 diabetes in overweight and obese adults. Polyphenols are plant compounds that act like antioxidants and may help prevent degenerative diseases like cancer, osteoporosis, and cardiovascular disease.
Researchers at the Institute of Nutrition and Functional Foods in Quebec conducted a parallel, double-blinded, randomized controlled trial with 41 overweight and obese adults. Participants had insulin resistance and abdominal adiposity, both risk factors for type 2 diabetes.
Participants were randomized into two groups. The experimental group consumed a zero-calorie beverage containing 333 milligrams of strawberry and cranberry polyphenols (SCP) daily for six weeks. The control group drank a flavor-matched beverage with 0 milligrams of SCP. The amount of SCP was equivalent to 120 grams of fresh fruit or 10 medium California strawberries.
After six weeks of drinking the SCP beverage, insulin sensitivity had significantly improved in the experimental group versus the control group.
There are a few ways researchers think polyphenols may help improve insulin sensitivity. First, polyphenols may stimulate glucose uptake and reduce oxidative stress. They may also alter the gut microbiome, reducing inflammation and insulin response, or change insulin sensitivity within the skeletal muscle.
Insulin ushers glucose out of the bloodstream and into the cells. In people with early insulin resistance, the cells stop responding to insulin well, leaving extra glucose in the blood. The pancreas compensates by producing more insulin, but the surge is unsustainable over a long period of time and eventually the pancreas can’t handle the burden. When the pancreas tires out, glucose builds up in the bloodstream, leading to type 2 diabetes. If polyphenols can prevent the pancreas from overproducing insulin, they can help prevent type 2 diabetes. The polyphenol-rich SCP beverage kept participants from overproducing insulin.
This exploratory trial found that consuming 333 mg of polyphenols from strawberries and cranberries – the equivalent of 8 medium strawberries a day –may help prevent type 2 diabetes by improving insulin sensitivity and preventing the overproduction of insulin.
Paquette, M., Medina Larque, A.S., Weisnagel, S.J., Desjardins, Y., Marois, J., Pilon, G., . . . Jacques, H. (2017). Strawberry and cranberry polyphenols improve insulin sensitivity in insulin-resistant, non-diabetic adults: a parallel, double-blind, controlled and randomized clinical trial. British Journal of Nutrition. doi: 10.1017/S0007114517000393