Bodybuilders, athletes and those interested in health and fitness have a plethora of protein supplements to choose from today. From a biological point of view, the most superior proteins in terms of promoting increased muscle protein synthesis (MPS) are milk proteins. Milk contains two major proteins, whey and casein, which respectively constitute 20 and 80% of milk protein. There are other subfractions to these major proteins in milk that emerging research suggests also produce other health benefits. For example, one smaller peptide fraction of milk has been compared to prescription drugs called ACE inhibitors in their ability to lower elevated blood pressure. And unlike the drugs, the natural peptides in milk don't cause any side effects. Milk protein, however, was not always recognized as being the best natural protein. When I began bodybuilding over 50 years ago, the predominant protein supplements were derived from egg sources, specifically the albumin or white portion of the eggs. A few rare brands did contain whole egg, but because the yolk of the egg is also the source of its fat, such whole egg supplements were by necessity higher in fat, although the processing of the protein did remove a large amount of the natural fat content. Egg protein supplements were popular because eggs were rated the most ideal source of protein and the food with the highest biological value of all proteins. The "biological value" was a measure of how much protein could be absorbed and retained in the body. What determined the biological value of a protein was its balance of essential amino acids or amino acids that must be supplied in the diet and cannot be synthesized in the body. Whole eggs had a biological value (BV) of 93.7, while milk followed closely with a BV of 84.5. Fish rated a BV of 76, while the number for beef was 74.3. Based on this, egg protein supplements were the dominant supplemental protein in the 60s and 70s.
But what wasn't realized at the time was that most of the popular brands of egg protein supplements were derived from the white of the eggs and didn't contain the yolk portion. This was problematic from a nutritional point of view because the BV rating of 93.7 was based on the whole egg. Many bodybuilders have been told that egg whites are pure protein not containing any fat, so they mistakenly believe that all the protein in eggs is contained in the whites. They simply discard the yolks in the false belief that it's just the source of fat in eggs. In reality, the yolk contains half the amino acids in eggs and explains why only whole eggs rate a high biological value. Even worse, the yolk of eggs is the source of not just half the amino acid content of eggs, but also the majority of nutrients found in eggs. While it's true that egg whites contain 67 . . .