Strawberries, bilberries, lingonberries, and chokeberries may blunt the insulin response to the starch-rich bread, and offer a means of reducing the risk of diabetes, says a new study from Finland.
Elevated circulating levels of insulin – hyperinsulinemia – has been linked to a variety of metabolic diseases, most notably type-2 diabetes. New results published in the Journal of Nutrition indicated that consuming berries with both white and rye bread leads to lower insulin responses.
“We conclude that when white bread is consumed with berries, less insulin is required for maintenance of normal or slightly improved postprandial glucose metabolism,” wrote researchers led by Riitta Torronen from the University of Eastern Finland.
“The lower insulin response to rye bread compared with white bread can also be further reduced by consumption of berries.”
The benefits of berry extracts
Berries, and the polyphenols they contain, have previously been reported to have blood sugar management activity, linked to both an inhibition of the digestion of carbohydrate rich foods (for example, by inhibiting starch digesting enzymes alpha-amylase and glucoamylase ), as well as reducing the absorption of carbohydrates in the gut.
The majority of the science, however, has been in lab and animal models, and “the evidence of the effects of berries on postprandial metabolic responses to starch in humans is limited”, wrote Torronen and her co-workers.
For the new study, they recruited between 13 and 20 healthy women to participate in three randomized, controlled, crossover, two-hour meal studies. The women consumed white bread, rye bread, or both, with or without 150 grams of a berry purée of strawberries, bilberries, lingonberries raspberries, cloudberries, chokeberries, cranberries, or blackcurrants.
Results showed that only strawberries, bilberries, lingonberries, and chokeberries reduced the insulin response after eating white bread or rye bread.
“Only strawberries (36%) and the berry mixture (with white bread, 38%; with rye bread, 19%) significantly improved the glycemic profile of the breads,” added the researchers.
“The lower insulin response after ingestion of berries implies that less insulin is required and secreted for maintenance of normal or slightly improved postprandial glucose metabolism,” they explained in the Journal of Nutrition article.
“A lower postprandial insulin requirement may be beneficial in the short term and long term. In the short term, a lower insulin response prevents hypoglycemia and inappropriate increases of free fatty acids and stress hormone concentrations, which are often seen during the late postprandial period after consumption of refined carbohydrates
“Regular consumption of diets with a low postprandial insulin response may increase first-phase insulin secretion, indicating improved pancreatic beta-cell function, and modulate the inflammatory status.
“Thus, regular consumption of foods with a lower postprandial insulin requirement, such as rye bread and berries, may help in the prevention of type 2 diabetes and can be recommended especially for individuals at high risk of this disease.”
Source: Journal of Nutrition
2013, Volume 143, Pages 430-436, doi: 10.3945/jn.112.169771
“Berries Reduce Postprandial Insulin Responses to Wheat and Rye Breads in Healthy Women”
Authors: Riitta Törrönen, Marjukka Kolehmainen, Essi Sarkkinen, Kaisa Poutanen, Hannu Mykkänen, and Leo Niskanen