I'd like to zero in briefly on this misconception I mentioned yesterday. I hadn't really heard what it was all about, probably because before I came to South Africa I was pretty carnivorous. Here, though, I'm about 90% vegetarian, particularly in the village (mainly out of laziness and the quick spoiling time of meat). Seems like the idea was the meat contains "complete" protein with all the amino acids, while vegetarians should combine foods like beans and rice to get that same completeness. Sounds plausible, right? Humans did evolve as omnivores.
Here’s where it gets interesting. The idea that plant based foods were deficient in certain amino acids was based on studies of the growth of young rats done in the early 1900′s. A subsequent study done in 1952, looked at human requirements for essential amino acids and found them to be very different from rats. Additionally it showed that the requirements for all the essential amino acids in humans could be met by many unprocessed plant foods, without combining, in excess of the recommended levels. The bottom line is that plant protein is “complete.” Vegetables and grains contain all essential amino acids and non-essential amino acids in varying proportions, and will supply in excess of what is necessary for your daily needs.