This review discusses the importance of protein structure, digestibility, and bioavailability in human nutrition, focusing on different protein sources and their impact on health. Plant-based proteins, such as those from legumes, nuts, and seeds, often contain anti-nutritional factors that can reduce their bioavailability compared to animal proteins. Animal proteins are generally more digestible and have higher amino acid bioavailability. Alternative protein sources, such as soy and potato proteins, also vary in digestibility and nutritional value based on processing methods. The review highlights the nutritional requirements for various population groups, including adults, older adults, children, and special groups like pregnant women and athletes. Protein intake recommendations vary based on age, sex, and activity levels. For example, older adults require higher protein intake to prevent muscle loss, while children need adequate protein for growth and development. Pregnant women have increased protein needs to support fetal growth, and athletes may require more protein for muscle repair and growth. The review also discusses protein quality measures, such as the Protein Digestibility-Corrected Amino Acid Score (PDCAAS) and the Digestible Indispensable Amino Acid Score (DIAAS), which assess the nutritional value of proteins based on digestibility and amino acid availability. These scores help in evaluating the quality of protein sources and their potential to meet nutritional requirements. The review further explores the impact of protein structure on digestibility and bioavailability, noting that certain structural features can hinder digestion and reduce nutrient absorption. Factors such as cooking, processing, and the presence of anti-nutritional factors can influence protein digestibility and bioavailability. The review also addresses future food proteins, including cultured meat, plant-based proteins, single-cell proteins, and insect proteins, which have the potential to meet increasing global protein demands while reducing environmental impact. However, these proteins may have different digestibility and bioavailability profiles compared to traditional animal proteins. Finally, the review discusses the potential for future food proteins to cause food allergies, emphasizing the need for careful evaluation of new protein sources before they are introduced to the market. The importance of considering both the quantity and quality of protein sources for a healthy diet is highlighted, with a call for further research to fully understand the nutritional quality of alternative protein sources.This review discusses the importance of protein structure, digestibility, and bioavailability in human nutrition, focusing on different protein sources and their impact on health. Plant-based proteins, such as those from legumes, nuts, and seeds, often contain anti-nutritional factors that can reduce their bioavailability compared to animal proteins. Animal proteins are generally more digestible and have higher amino acid bioavailability. Alternative protein sources, such as soy and potato proteins, also vary in digestibility and nutritional value based on processing methods. The review highlights the nutritional requirements for various population groups, including adults, older adults, children, and special groups like pregnant women and athletes. Protein intake recommendations vary based on age, sex, and activity levels. For example, older adults require higher protein intake to prevent muscle loss, while children need adequate protein for growth and development. Pregnant women have increased protein needs to support fetal growth, and athletes may require more protein for muscle repair and growth. The review also discusses protein quality measures, such as the Protein Digestibility-Corrected Amino Acid Score (PDCAAS) and the Digestible Indispensable Amino Acid Score (DIAAS), which assess the nutritional value of proteins based on digestibility and amino acid availability. These scores help in evaluating the quality of protein sources and their potential to meet nutritional requirements. The review further explores the impact of protein structure on digestibility and bioavailability, noting that certain structural features can hinder digestion and reduce nutrient absorption. Factors such as cooking, processing, and the presence of anti-nutritional factors can influence protein digestibility and bioavailability. The review also addresses future food proteins, including cultured meat, plant-based proteins, single-cell proteins, and insect proteins, which have the potential to meet increasing global protein demands while reducing environmental impact. However, these proteins may have different digestibility and bioavailability profiles compared to traditional animal proteins. Finally, the review discusses the potential for future food proteins to cause food allergies, emphasizing the need for careful evaluation of new protein sources before they are introduced to the market. The importance of considering both the quantity and quality of protein sources for a healthy diet is highlighted, with a call for further research to fully understand the nutritional quality of alternative protein sources.