Lentils are one of the most protein-dense plant diets available. However, unlike animal protein, legumes have a low methionine level (an necessary amino acid for the body), making their protein incomplete. People who eat little or no animal protein, on the other hand, can combine beans with grain products or nuts to have a complete protein (which contains all of the essential amino acids). Adults do not need to pursue this complementarity inside the same meal because acquiring it within the same day is typically sufficient. On the other hand, it is better to achieve protein complementarity in the same meal in children, adolescents, and pregnant women.