Classification of the Two Main Amino Acid Types
Essential Amino Acids
These must be supplied though a person’s diet as they cannot be manufactured by the body. Check the nutritional profile of the foods and supplements you consume to ensure they contain a full complement of essential amino acids.
The nine essential amino acids are:
Histidine
Isoleucine
Leucine
Lycine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Non-Essential Amino Acids
These are made by the body from essential amino acids, or through the breakdown of proteins. If the foods you consume contain amino acids mostly of the non-essential type, you may need to supplement your diet so as to include more of the essential kind. The 12 non-essential amino acids are:
Alanine
Cysteine
Cystine
Glutamine
Glutathione
Glycine
Histidine
Serine
Taurine
Threonine
Asparagine
Apartic acid
Proline
Evaluating Your Proteins
Which Types Are best?
At face value, the total protein composition of a food is not the best indicator of whether it will promote quality gains in muscle size or even the maintenance of good health.
First of all, lean protein sources are preferable to those containing significant amounts of fat, such as those found in fast foods and fatty meats. A lean protein source will be better assimilated and more efficiently used by our tissue than one containing a great deal of fat.
Secondly, to be considered high quality, proteins must comprise a high percentage of essential amino acids, and the total usable protein content of a given type must also be high. A reliable indicator of whether a protein source could be considered a good, or bad, option or has a large distribution of usable essential amino acids is its combined Biological Value (BV), Protein Efficiency Ratio (PER), and Net Protein Utilization (NPU) reading.
Biological Value (BV)
When assessing a protein’s quality, the first major indicator to consider is its biological value, or, bio-availability. This will tell us how efficiently our bodies can use this protein – it’s the percentage of a given protein source that the body is able to absorb and utilize. Protein sources are generally ranked according to their BV (or how bio-available they are once consumed).
ONCE THE GOLD STANDARD, EGGS, WITH A RATING OF 100, HAVE SINCE BEEN OVERTAKEN BY WHEY PROTEIN, WITH ITS RANKING OF 104, AND WHEY ISOLATE, WHICH RANKS AT A HEFTY 120.
Lower on the list are: chicken/turkey (79), casein (77) beef (69), cow’s milk (60), brown rice (57) and soy beans (47 – soy protein has a BV of 74).
Nitrogen is a key element within protein that is responsible for tissue growth. Nitrogen accumulates in greater quantities whenever we consume higher quality protein sources and we achieve what they call a “Positive Nitrogen Balance”. This is a critical point that is often overlooked,
…POSITIVE NITROGEN BALANCE IS LIKELY THE SINGLE MOST IMPORTANT FACTOR IN GETTING YOU (AND KEEPING YOU) IN AN ANABOLIC STATE…
the positive nitrogen balance is likely the single most important factor in getting you (and keeping you) in an anabolic state – building muscle around the clock. If you dip into a negative nitrogen balance, you move into the catabolic state. This is where your body initiates a deconstruction of muscle to feed more physiologically important processes than your muscles! This is why it is a common practice to consume high-quality protein several times a day.
Protein Efficiency Ratio (PER)
Yet another way to measure a protein’s quality is by determining its protein efficiency ratio, or the rate at which an individual protein can sustain growth (determined in the lab by taking the weight, in grams, gained by a protein-fed test subject and dividing it by the amount, again in grams, of the specific protein this subject took).
Given that the quantity of one protein may promote greater weight gain compared to the exact quantity of another, it’s worth knowing which is which to ensure greater gains of our own. As one might expect, whey proteins score highest with a PER of 3.9. Eggs clock in at 3.1, fish, beef and chicken at 2.7, cow’s milk and casein at 2.5, soy at 2, and rice at 1.5.
Net Protein Utilization (NPU)
To ensure the proteins we consume are absorbed into our bloodstream at an efficient rate we must first assess their digestibility and utilization. The percentage of protein retained by the body after the digestion of a protein-containing foods is that food’s net protein utilization.
However, one caveat applies – while certain foods such as beef and chicken may have the exact same PER and be similar in their BV and NPU, beef, with its higher percentage of fat, may not be absorbed as fast (chicken also contains around half the calories of an equal serving of beef).
A list of common foods and supplements and their respective NPU percentages:
Whey protein: 92%
Eggs: 88%
Fish: 78%
Beef and chicken: 68%
Soybeans: 48%
Brown rice: 40%
White bread: 20%
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