I've also touched on the some of the arguments put forth by low protein proponents. In addition, there is a great deal of confusion about actual protein requirements in humans as well as potential adverse effects from excessive protein ingestion. There are many groups who feel that recommended protein intakes are overdone. This situation likely stems from several independent factors that all serve to come down in favor of low protein intakes. We can discuss some of these issues first and then discuss the actual data on protein requirements.
Protein appears to be receiving a bad rap for several reasons.
First, animal products are an excellent source of good balanced protein. Second, given the emphasis in nutrition over the last 15 years has been at lowering fat intakes and saturated fat intakes, sources of these items have been targeted for reduction in diets. Third, individuals with certain forms of renal disease can slow progression with a low protein diet. Fourth, high protein intakes have been associated with a greater degree of calcium excretion and reduced bone formation in young women suggesting that low protein diets may prevent osteoporosis. And fifth, low protein diets appear to extend lifespan.