In search of alternative proteins: unlocking the potential of underutilized tropical legumes

Protein is one of the essential nutrients required for almost every task of a human’s cellular life. Severe protein malnutrition, which can cause a fatal outcome, is the leading cause of death for infants and children in many African and Asian countries that have little to no access to complete proteins. Complete proteins, which contain all nine amino acids essential for human health, are usually found in animal-based foods such as meat and dairy products. The overconsumption of animal-based proteins, however, can potentially increase the risk of diet-related chronic diseases. Recent years have witnessed enhanced awareness about the health benefits of substituting animal-based proteins with plant-based proteins, especially in developed countries. Nitrogen-fixing grain legumes are considered important sources of protein in many developing countries because they are generally cheaper than meat or cereals. Extensive research has been conducted on several well-known legumes, notably soybean, which is the most economically important legume worldwide. Nevertheless, many lesser-known legumes with similar nutritional properties to soybean are still underdeveloped, including winged bean, lentil, lima bean, lablab, and bambara groundnut, which are commonly grown in the tropics. Only now are these species receiving more scientific attention. This review highlights the potential of these tropical legumes as future major sources of plant-based proteins, along with the critical research areas for their improvement. We provide insights into how these underutilized legumes could help resolve the global protein crisis and address food insecurity issues.