Characterization of the post-prandial insulinemic response and low glycaemic index of a soy beverage

Soybean is recognized as rich source of bioactive compounds for the improvement of glucose homeostasis. However, the post-prandial mechanisms of action have not been extensively described. The aim of this study is to determine the changes in glucose homeostasis and related factors after acute intake of a soy beverage. Twenty-nine subjects (15 women and 14 men, with an average age of 19.5 ± 1.2) ingested 500 mL of water, glucose (20.5 g/500 mL) and soy beverage (20 g of carbohydrate) in three separate sessions. Capillary blood glucose was monitored every 15 min until 120 min post-prandial, and blood samples were collected at baseline and after 60 min for insulin, incretin, free amino acids, antioxidant capacity and inflammation marker analysis. The increase in capillary glucose after soy-beverage intake was negligible. This is explained in part by an increase in 83% in insulin levels than induced with glucose alone, which is mainly mediated by a low insulin degradation ratio (determined by c-peptide ratio), incretins and likely also by the modulation of the antioxidant environment. No associations were observed between the insulin levels and soy amino acid uptake. It could be concluded that the acute low glycaemic response of a soy beverage may involves a relationship between incretin and insulin secretion and insulin degradation.