Final answer:
Vegans must carefully select and combine different plant-based proteins to ensure intake of all essential amino acids, as most plant proteins are incomplete. A diverse vegan diet can meet protein needs by combining plant foods like beans and corn for complete proteins.
Step-by-step explanation:
Vegans, who consume plant-based proteins exclusively, need to carefully consider their protein choices because plant proteins often lack one or more essential amino acids. Unlike animal proteins, which generally contain all essential amino acids, most single plant sources do not provide a complete amino acid profile. However, combining different plant foods can create a complete protein profile, supplying all essential amino acids needed by the body. For example, consuming beans and corn together forms a complete protein, as beans are high in lysine and corn is high in tryptophan.
Additionally, plant proteins may have lower biological values, potentially making them less efficient for the body to use. Biological value is a measure of how well the body can utilize the protein consumed; animal proteins like eggs and milk are closer to 100% biological value. Nonetheless, a diversified vegan diet can provide sufficient protein, provided vegans eat a variety of plant sources throughout the day to ensure they receive a balanced intake of amino acids.