Health benefits of Cyanidin-3-O-glucoside and other supporting natural compounds in black soybean (Glycine max (L.) Merrill): A narrative review

Soybeans hold a deep cultural significance with its origin in Asia. All of the current modern cultivars belong to the same Glycine max (L.) Merrill, which can be distinguished primarily by their seed coat pigmentation. These dark seed coat contains a unique profile of health-promoting compounds that remain under-recognised in global diets. Soybeans have served as a keystone in the Asian diets with nutrient-dense, versatile, and health-promoting benefits since ancient times. Besides, its fermented forms such as natto, miso, tempeh that have been consumed by Asians provided indirect support to the cardiovascular, immune, digestive, and metabolic health. On top of that, soybean consumption contributes to the differences in the national life expectancy across many Asian countries, however, these outcomes vary by nation and are shaped not only by their dietary intake but also by a broader lifestyle, environmental, and healthcare factors. This review focuses on the abundance of cyanidin-3-O-glucoside and other supporting natural compounds that define the seed coat's nutritional value in the black soybean. These phytochemical properties provide significant protection against common non-communicable diseases, including diabetes, obesity, and cardiovascular disorders; while the extracts demonstrate notable anti-cancer and anti-inflammatory potentials. This review also highlights the importance of integrating black soybean components into functional foods to enhance public health outcomes. In summary, black soybean products show potential for metabolic and cardiovascular health: seed coat extract supports weight and heart health (100 mg–2.5 g/day capsules, 40 g/day cookies, 30 g/day beans), while peptides (4.5 g/day for 12 weeks) improve fasting glucose.