Effects of soybean co-ingestion with carbohydrate on postprandial glycaemic, insulinemic and reactive oxygen species in healthy men: A pilot study

Postprandial hyperglycaemia induced by excessive intake of high carbohydrate (CHO) foods and beverages promotes oxidative stress which can cause many health risks such as cardio-metabolic diseases and diabetes. Protein when co-ingested with CHO beverages, has been shown to lower the postprandial glycaemic and insulinemic, which may help to attenuate postprandial reactive oxygen species (ROS) and oxidative stress. Soybean contains isoflavone which may provide potential benefits in regulating postprandial glucose and insulin levels as well as providing protection against ROS production. The aim of this study was to investigate the effects of soybean added CHO beverage on postprandial glycemic, insulinemic and reactive oxygen species responses in healthy men. Eight male [age 20.0 (1.2) years, body weight 59.2 (6.2) kg] consumed 500 ml of CHO added with soybean (SOY + CHO), CHO added with whey protein (WHEY + CHO) and CHO alone (Control) after an overnight fast, in a randomized counterbalanced order crossover design, separated by a one week period. Venous blood samples were collected after overnight fast (baseline) and at 30, 60, 90 and 120 min after consumption of the beverage. The mean area under the insulin curve was lower in SOY + CHO trial compared to CHO + WHEY trial. Similarly, SOY + CHO tended to have a lower postprandial ROS response than CHO + WHEY. However, no significant difference was observed between all beverages in all parameters. Soybean-based beverage may yield lower effect on postprandial ROS suggesting lower oxidative stress due to lower insulinemic responses, compared to whey protein when co-ingested with CHO.