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 [...]
Some writers claim that protein is protein, be it animal or plant, except for the way that animals are treated. How do you respond to this?
We have information that the primary difference between animal and plant proteins is their amino acid profiles and it is those profiles that direct the rates at which the absorbed amino acids are put to use within the body. Animal based proteins, of course, are much more similar to our proteins, thus are used more readily and rapidly than plant proteins. That is, ‘substrate’ amino acids derived from animal based proteins are more readily available for our own protein synthesizing reactions which allows them to operate at full tilt. Plant proteins are somewhat compromised by their limitation of one or more amino acids. When we restore the relatively deficient amino acid in a plant protein, we get a response rate equivalent to animal proteins. My own lab produced experimental data to support this view–and of course, similar observations of years past in other laboratories can also be interpreted in this way.
Some of the profile differences between animal and plant proteins have been previously noted by the ratios of arginine to lysine which are predictive, in turn, of tissue responses.
Animal proteins also have a higher concentration of sulphur containing amino acids that get metabolized to acid-generating metabolites. As a result, a slightly lower physiological pH must be corrected and buffers like calcium are used to attenuate these adverse acid effects–to the disadvantage of the host.
But my main thesis, insofar as my own work is concerned, is that our observations on protein and cancer, although studied in considerable detail, were signals of hypotheses that were more important and more global. [...]