When searching for information about protein supplements, you will often come across two terms – complete proteins and incomplete proteins – but what do these terms mean? How should you make a choice on the dietary protein supplement you choose or be certain that you are getting sufficient protein in your diet?
Complete proteins, often called whole proteins are those that contain the essential amino acids in the right proportions for human health. Essential or ‘indispensable’ amino acids (as they are also called), are those that cannot be made by the human body. As our bodies cannot store these amino acids in the way that we can store fat for later use, for example, we need to take in an adequate supply every day.
The Essential Amino Acids
To clear up any confusion about whether there are eight or nine Essential Amino Acids, both are correct, but it depends on your age! Histidine is the extra one and is needed by babies and young children – adults can normally make sufficient for themselves.
Wikipedia publishes a table showing the optimum amino acid profile that makes up a complete protein, quoting figures recommended by the Institute of Medicine’s Food and Nutrition Board. The essential ones are Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan and Valine. Their page is an invaluable resource to look at it here.
What Does The PDCAAS Score of a Protein Mean?
Some proteins score higher than others on a scale called the Protein Digestibility Corrected Amino Acid Score or PDCAAS; this rating was adopted by both the FDA (Food and Drug Administration) and the WHO (World Health Authority). It provides a clear way of understanding the quality of any type of protein based on the amino acid requirements of people and the digestibility of their digestibility in each type of protein.
The highest score possible is 1.0, achieved by whey and casein milk proteins, egg whites and soy protein isolate. However, other protein sources are excellent such as micoproteins (Quorn for example) and it is important to stress that most UNREFINED foods contain sufficient of all the essential amino acids for health, so sources such as Amaranth, Quinoa and Buckwheat are described as complete protein foods although they do not get a ‘top marks’ score on the PDCAAS scale.
The Consequences of Amino Acid Deficiencies
Most foodstuffs contain at least a small amount of each of the twenty amino acids. However, many foods are deficient in the essential amino acids that our bodies cannot make for themselves. They may contain all of them, but the quantities of some may be very low – especially in vegetable protein sources.
Lysine is the essential amino acid that is most likely to be lacking. It is very important to take in sufficient Lysine because it helps the body to absorb calcium and build collagen. It is essential in the production of Carnitine that not only helps to lower cholesterol but also to convert fatty acids to energy.
Deficiency of Lysine can cause serious health problems including anemia, tiredness, feeling dizzy and nauseous as well as bloodshot eyes and long-term problems such as reproductive disorders in women.
Of particular concern for vegetarians is the fact that two other two amino acids that are most likely to be lacking in vegetable protein sources (although to a lesser degree) and these are Methionine and Threonine.
Scientific experiments as long ago as the 1930s, conducted by William Cumming Rose found that his human volunteer subjects all experienced symptoms of exhaustion, dizziness and anxiety to some degree when their diets were deficient in one or more of the essential amino acids.
You can read more about this fascinating man who was born in 1887 and died in 1985 and had a long and distinguished career, first at the University of Texas and later at the University of Illinois in this article.
Vegetarians and Vegans Can Still Get All The Essential Amino Acids From Vegetable Sources
People on a vegetarian or vegan diet need to be especially careful to eat a variety of different protein sources throughout the day to ensure that they get sufficient of all the amino acids their bodies require.
The teaching used to be that food combining was essential, that complementary proteins had to be eaten at the same meal so that the body could utilise them properly. However more recently, teaching is that these complementary proteins only need to be eaten during the same day (or during the same twenty-four hour period) to be just as effective.
It seems that traditional diets have developed over time to provide vegetarian dishes providing all the necessary amino acids in the diet. An example of this would be a Mexican dish combining maize and beans or a Japanese dish using both soy and rice.
Taking Protein Powder Supplements
We have discussed the benefits of each type of protein powder supplement in depth in other articles on this site. The best for non-vegetarians are whey and casein from milk and for vegetarians and vegans, Soy protein isolate is the best choice.
Whether or not to consume protein supplements is a personal choice but they may help you to reach your personal goals (these might be either building muscle or losing weight). However, whilst it is certainly easier for those eating meat and fish to take in adequate protein in their diets, protein powder supplementation does make it much easier to be sure of the quality and the quantity of protein consumed each day.