Gut: The Inside Story of Our Body’s Most Underrated Organ

by Giulia Enders

However, maintaining a healthy meat-free diet that does not lead to nutritional deficiencies is more difficult than most people think. Plants construct different proteins than animals, and they often use so little of a given amino acid that the proteins they produce are known as incomplete. When our body tries to use these to make the amino acids it needs, it can continue to build the chain only until one of the amino acids runs out. Half-finished proteins are then simply broken down again, and we excrete the tiny acids in our urine or recycle them in our body. Beans lack the amino acid methionine; rice and wheat (and its derivative meat substitute, seitan) lack lysine; and sweetcorn is, in fact, deficient in two amino acids: lysine and tryptophan. But this does not spell the final triumph of the meat eaters over the meat-avoiders. Vegetarians and vegans simply have to be cleverer in combining their foods. Beans may be lacking in methionine, but they are packed with lysine. A wheat tortilla with refried beans and a yummy filling will provide all the amino acids the body needs for healthy protein production. Vegetarians who eat cheese and eggs can compensate for incomplete proteins that way. For centuries in many countries around the world, people have intuitively eaten meals made up of foodstuffs that complement each other: rice and beans, pasta with cheese, pita bread and hummus, or peanut butter on toast. In theory, combining does not even have to take place within one m...