Final answer:
Vegans and vegetarians can complement their proteins by combining different plant protein sources to obtain all essential amino acids.
Step-by-step explanation:
Vegans and vegetarians may complement their proteins by combining different plant protein sources to provide all the essential amino acids. Most plant foods do not contain complete proteins, meaning they lack one or more essential amino acids. However, by pairing foods with different limiting amino acids, known as complementary proteins, they can obtain adequate amounts of essential amino acids. For example, legumes like beans are low in lysine but contain adequate amounts of tryptophan, while grains like corn are low in tryptophan but contain sufficient lysine. By consuming legumes and grains together, vegans and vegetarians can create a complete protein source.