There are three macronutrients in food: carbohydrates, fat and protein, ‘macro’ in the sense that they comprise almost all of the weight and calories of food. Vitamins and minerals are the micronutrients.

Protein, ever since its discovery in 1839, has been considered by many people to be an exceptionally important nutrient, often assuming that the more we consume the better. Its name comes from the Greek word, proteios, meaning ‘of prime importance’—an auspicious and almost mystical beginning for the future of this nutrient! Add to this importance the long standing impression by most people that protein is exclusive to animal source foods.

We now know, however, that this importance is exaggerated, to mythical proportions. For a starter, protein is not exclusive to animal-based foods. In the late 1800s protein was also found to be present in plant foods. Yet the myth of its being tightly or even exclusively linked to animal-based foods still lingers. Simply ask a non-meat eating vegan how many times they are asked, “But where do I get my protein?”

This bias implying that meat is the sole source of protein was encouraged over these many decades by ‘science’. Research findings, for example, were showing that animal-based proteins are utilized by the body more efficiently. This efficiency of utilization referred to increased body growth rate among other effects, with greater efficiency being described as greater ‘biological value’ or higher quality. But it was only animal-based proteins that have high quality.

Because most people obviously like high quality, animal-based protein became the protein of choice. In effect, this history evolved through the prism of linguistics to give a profound self-perpetuating paradigm.

The problem with this proposition is that high quality does not necessarily mean better health. Increasing body growth may be useful for farm animal production and growing children faster, but it also means growing cancer cells faster, improving conditions for heart disease and speeding up aging—each of which has been documented. Growing young girls more rapidly means earlier sexual maturation, higher circulating levels of estrogen and, eventually, elevated breast cancer risk.

My laboratory in a long series of studies conducted over more than two decades showed that the growth of experimental cancer is markedly stimulated by the consumption of animal-based casein, the main protein of cow’s milk. This occurs in part because this animal source protein stimulates the production of the same growth hormone that spurs childhood growth. Plant based proteins tend not to promote these events, not at least when fed at levels typically found in the whole foods, plant based (WFPB) diet. These findings beg the next important question of what is the proper amount and kind of protein for individuals to consume for optimum health.

To answer this question, let’s first consider the officially created recommended daily allowance (RDA). It was first determined and published in 1943 by the prestigious National Academy of Sciences for the purpose of supporting good nutrition for the American military during wartime.

This assessment begins with a determination of the amount of protein to be consumed to compensate for the amount of protein (as nitrogen) excreted. This estimate, called the minimum daily requirement, was about 0.5 gms/kg of body weight, equivalent to about 6% of total diet calories. Because this estimate was determined on a small, random sample of individuals (from the larger population), it was adjusted upward by about two standard deviations to insure adequate intake for everyone in the larger population. This became 0.8 gm/kg body weight—the well known recommended daily allowance (RDA). For a 70 kg (144 lb) adult male, this is 56 gms; for a 60 kg (132 lb) female, 48 gms. Assuming a daily consumption of 2000 calories (cal) and an energy content of 4 cal/gm protein, this corresponds to 11.2 % dietary protein for a 2000 cal diet, or 9.0% dietary protein for a 2500 cal diet. To round it off for convenience, a diet of 10% protein (the RDA) easily represents enough protein for good health. This estimate, first made official in 1943, has since been officially reviewed 14 times by an expert panel of scientists, thus fixing it as a well-established figure.