Berries are rich sources of various polyphenols which may be beneficial in the regulation of blood glucose. In vitro and animal studies have shown that polyphenols and polyphenol-rich extracts of foods, including berries, may inhibit digestion and absorption of carbohydrates and thereby suppress postprandial glycemia. However, current evidence on the effects of berries on postprandial glycemic responses in humans is limited.~The purpose of this study is to investigate the effects of berries on postprandial glycemic responses (blood glucose and insulin) to starch or sucrose in healthy subjects. It consists of five substudies each of which includes 2-4 meals with different berry species typically consumed in Finland and a reference meal without berries. The following combinations of carbohydrates and berries are studied:~Studies 1-2: white wheat bread (starch) is consumed with several berry species~Study 3: white wheat bread or rye bread is consumed with a mixture of berries~Study 4: sugar (sucrose) is consumed with berries and berry nectars~Study 5: a sugar-sweetened bakery product (starch + sucrose) is consumed with berries and berry nectar.
The purpose of this study is to investigate whether berries are effective in lowering blood glucose and insulin responses to meals containing starch or sucrose.