While studying pre-veterinary medicine at Pennsylvania State University, Dr Campbell became interested in animal nutrition, and wanted to explore the possibility of increasing protein consumption in farm animals as a means to increase their production, which led him to discover that many of the theories that exist still today regarding animal protein are merely conjecture.
We know that the three macronutrients that humans need to live are carbohydrates, fats and proteins, yet, when it comes to protein, we tend to think only about meat. This is because meat is the only food made up entirely of protein (as well as fat, a small quantity of water, and very little other macronutrients). This explains the common belief that meat is the best source of protein.
Over the last few centuries, cultural prejudice has linked the consumption of plant foods to the lower classes, and a belief that the upper classes were the only ones who could afford meat and dairy products. This also led to the firm belief that the biggest food problem in third world countries was known as the protein gap, or a lack of protein in the diet, caused by a lack of access to meat, which was believed to be responsible for malnutrition in these countries, when the real problem was lack of variety in the diet.
These cultural prejudices were then accompanied by another prejudice based on scientific fact: to replenish protein in the body, human beings need 8 essential amino acids, which are all found in meat; this information confirmed the belief that eating meat was the quickest way for us to get the nutrients we need. This is how the status of meat was established as a higher quality source of protein than vegetables. The thing is, the efficacy and speed of protein absorption does not necessarily equate to better health. This is primarily because vegetables, as a whole, contain all the essential amino acids and nutrients that are not found in meat. The China Study also reveals many other reasons why animal products and health are terms that really should not go hand in hand.