Peas, common bean, cowpea, chickpeas, and lentils are the major protein sources in the grain legume group and have an important place in terms of human and animal feeding. High protein content and other nutrient compositions like micronutrients, dietary fiber, prebiotics, and folates make leguminous seeds an important food source. Low glycemic index (GI) content of food legumes is important for long-term benefit of health. Isoflavones within legumes (isoflavones = an active substance that stabilizes the estrogen hormone) play an important role in the resistance mechanism of the plant, in the formation of nodules in the root, and have human health benefits. Proteins, glycosides, tannins, saponins, alkaloids, and many other bioactive substances in grain legume seeds increased the importance of legumes for human consumption. In developing and underdeveloped countries, because of the high cost of animal proteins, people meet their everyday protein requirements from cheaper legumes. In addition, they get additional supply of the abovementioned bioactives for a better health and nutrition. © Springer Nature Switzerland AG 2021. All rights reserved.