Effect of soy protein isolate preload on postprandial glycemic control in healthy humans

• Published in: Nutrition (Burbank, Los Angeles County, Calif.) Vol. 32; no. 9; pp. 965 - 969
• Main Authors: Kashima, Hideaki, Uemoto, Saori, Eguchi, Kohei, Endo, Masako Yamaoka, Miura, Akira, Kobayashi, Toshio, Fukuba, Yoshiyuki
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2016; Elsevier Limited
• Subjects: Adult; Amino acids; Blood; blood glucose; Blood Glucose - drug effects; Diabetes; Dose-response; Dose-Response Relationship, Drug; fasting; Female; Females; gastric emptying; Gastroenterology and Hepatology; Glucose; Glucose Tolerance Test - statistics & numerical data; glucose tolerance tests; glycemic control; glycemic effect; Humans; Hyperglycemia; Insulin; Insulin - blood; insulin secretion; Japan; Lactose; Lactose intolerance; liquids; Male; Oral glucose tolerance test; Postprandial Period - drug effects; Proteins; Reference Values; Sample size; Soy products; Soy protein isolate; Soybean Proteins - administration & dosage; Soybean Proteins - blood; Soybean Proteins - pharmacology; Studies; Values; Variance analysis; whey protein; Young Adult; Japan; Oral glucose tolerance test; Dose-response; Glucose; Soy protein isolate; Insulin
• ISSN: 0899-9007; 1873-1244; 1873-1244
• DOI: 10.1016/j.nut.2016.02.014

Premeal consumption of whey protein improves the postmeal glycemic profile, but little information exists on soy protein. The study aim was to examine the effect of consuming different amounts of a soy protein isolate (SPI) before a 75-g oral glucose tolerance test (OGTT) on subsequent glycemic control. After overnight fasting, eight healthy young subjects consumed a 400-mL liquid meal containing 0 g (SP0), 20 g (SP20) or 40 g (SP40) SPI. Thirty minutes after SPI consumption, an OGTT was performed to evaluate the individual glycemic response. Blood glucose and plasma insulin concentrations were measured immediately before the SPI preload (i.e., 30 min before the start of the OGTT) and before (−10 min) and during the OGTT (15, 30, 45, 60, 90, and 120 min). The incremental area under the curve and peak blood glucose response were significantly less for SP40 than those for SP0 and SP20. Insulin secretion was significantly higher for SP20 and SP40 than that for SP0 before and at 15 min after oral glucose consumption. The incremental area under the curve of plasma insulin was significantly higher for SP20 and SP40 than that for SP0. An SPI preload of 40 g, but not 20 g, improved glycemic control in young healthy subjects. Glycemic control appears to be attributed not only to the exaggerated insulin response to SPI preload, but also to non-insulin dependent mechanism(s), such as delayed gastric emptying. •Soy protein isolate consumption before oral glucose tolerance test (as a simulated carbohydrate-rich main meal) improves postprandial glycemia.•Soy protein isolate preload enhanced the insulinotropic effect in a dose-dependent manner.•This positive effect could be induced by not only stimulating insulin secretion but also by possibly slowing gastric emptying.