Countless thousands of vegetarians thereafter referred to Lappe's charts and tables and struggled to understand the intricacies of balancing tryptophan, lysine, methionine, and all the other amino acids. Therefore, balance plant foods weak in one amino acid but strong in a second amino acid, with other plant foods strong in the first but weak in the second. Well, simple to some people, but not so simple to others, who eventually gave up the effort and went back to a meat-based diet out of fear of missing one or another of the amino acids. And yet the central thesis of this best-selling book, one which even today many vegetarians believe in, is false. It's true that plant foods have more of the requirements of amino acids than of others.
Rice is strong in tryptophan, methionine, and valine, and weak in isoleucine and lysine.
The same is true for virtually all other plant foods. In fact, some plant foods which do not quite provide the requirement for total protein, such as sweet potatoes, DO provide the minimum requirement for ALL of the essential amino acids. They noticed that baby rats fed on a plant food diet did not grow as fast as other rats who ate the same diet plus a lysine supplement. Unfortunately, the nutritional requirements of rats and humans are quite different, and this was quickly demonstrated by experiments on humans. Studies in which humans have been fed wheat bread alone, or potatoes alone, or corn alone, or rice alone, have ALL shown that these plant foods contain not only enough protein, but enough of ALL of the essential amino acids, to support growth and maintenance of healthy adults.