Assessment of In vivo Glycemic Index, Glycemic Load, and Postprandial Glycemic Response of a Soy-Based Protein Beverage

Nutrition is essential for the maintenance of metabolic health, especially in individuals at risk of glucose dysregulation. This study aimed to determine the glycemic index (GI) and glycemic load (GL) of a soy-based protein beverage (D-care from Ma-Jusmin Co., Ltd.). The GI assessment followed ISO 26642:2010 guidelines and was conducted in 10 healthy adults (equal number of males and females). Postprandial blood glucose responses were measured over 120 minutes after consuming the test beverage and a glucose reference solution, both containing 50 g of available carbohydrates. The soy-based beverage resulted in significantly lower blood glucose levels at 15, 30, 45, 60, and 90 minutes (P < 0.001) compared to the glucose solution. The peak glucose level for the glucose solution occurred at 45 minutes (161.55 ± 5.79 mg/dL), while the soy beverage peaked earlier at 30 minutes (109.90 ± 2.87 mg/dL). The highest incremental area under the curve (IAUC) was observed between 60–90 minutes for the glucose solution (1,272.75 ± 171.06 mg × min/dL), whereas the soy beverage showed a much lower peak (309.00 ± 81.68 mg × min/dL). The total IAUC at 120 minutes was also significantly lower for the soy beverage (1,273.74 ± 218.31 vs. 4,583.05 ± 433.99 mg × min/dL; P < 0.001). Accordingly, the GI and GL were calculated to be 26.36 ± 2.95 and 8.09 ± 0.91, respectively. The beverage is classified as low-GI and low-GL based on these findings, which suggest that it may be an acceptable choice for postprandial glycemic control.