Protein Quality Evaluation And The Serious Bodybuilder


by Stephen Terrass

It's no secret to the most bodybuilders that the one of the greatest nutritional requirements is increased protein intake. Countless products have been made available to supply this need. There is milk protein, soy protein, egg protein, milk and egg protein and so on. To a bodybuilder who is new to the use of supplements, the choice can be rather confusing. As a result, many will make the choice on price, the quantity of protein per serving or maybe taste. Others will look at ingredients in the product other than the protein. While all these issues are worth considering when looking at protein supplements, they are not as important as looking at the protein itself.

The confusion about which protein is preferable is not restricted to the new protein user. Many of those who have been working with these supplements for years want clarification as to the differences between them. It's not hard to find information on protein products. It's just hard to find information which is not laced with propaganda.

When a bodybuilder trains with weights they are damaging the muscles in the process. The repair and eventual growth of the muscles requires that the muscle which is damaged or catabolised during the workout be compensated for. Because protein is a primary constituent in muscle tissue, dietary protein is the key to this compensation.

Many experts have opinions on how much protein a bodybuilder should consume in a day. Depending on who you listen to, you may find that just over two grams of protein per kilogram of body weight is a typical recommendation. In truth, many factors should be considered when figuring how much protein is likely to be required to repair damage and then maximise muscle size. This includes; the nature and severity of the training; the person's body size; their biochemical uniqueness; and a factor which is seldom considered when deciding on the level of intake - the biological quality of the protein being consumed.

nitrogen retention

The term nitrogen retention may be familiar to a lot of bodybuilders. It is referred to frequently when discussing lean muscle maintenance and growth. This emphasis on nitrogen is warranted as it is clearly one of the most vital issues in protein usage.

In order to be used efficiently by the body for lean muscle production, amino acids must be available in certain quantities and in certain ratios. Of the greatest importance are the eight essential amino acids (l-leucine, l-isoleucine, l-valine, l-tryptophan, l-threonine, l-methionine, l-phenylalanine and l-histidine) which form a complete protein. These amino acids are called 'essential' because they are necessary for health but cannot be made by the body, thus requiring dietary intake. Certain other amino acids are known as 'non-essential' which is misleading, because they are still needed for health. The difference is that they can be made from essential amino acids in the diet.

The consumed dietary amino acids enter a 'pool' from where they are able to be taken to manufacture tissue protein. If the pool does not contain correct quantities and ratios of all the amino acids needed to meet the many demands for protein, then nitrogen (a component of amino acids) will be excreted. The nitrogen is coming from the existing amino acids which could not be used for protein production due to a lack of certain other amino acids. Therefore the more nitrogen is excreted, the less the protein has been utilised.

For the bodybuilder, the implications of inefficient protein utilisation are particularly worrying. For one thing, this obviously means that muscle repair and building will be less efficient. In addition, usable protein is needed for maintenance of non-skeletal tissues (e.g. the heart, liver, blood vessels, etc.), hormone and blood production, and countless other purposes. As you can probably imagine, the stress on these other areas may be greater for those involved in rigourous weight-training.

Protein Evaluation

Dietary protein, in and of itself, is of absolutely no value to the human body. Its only value is as a source of various single amino acids, which are often called the 'building blocks' of protein. To a great extent, how much benefit a protein supplement will depend on the source of the protein.

PER (protein efficiency ratio)

Until fairly recently, to assess the quality of a protein source much of the emphasis was put on a scale known as PER (protein efficiency ratio). This rating is based on the analyzing the growth of animals consuming a fixed amount of dietary protein from a single source. While PER assessment may well be of value in estimating the possible value of a protein source, one of its major deficiencies is the fact that it does not reflect human growth data.

FAO/WHO assessment

At the end of the last decade, the United Nations Food & Agriculture Organisation (FAO) and the World Health Organisation (WHO) set out to evaluate assessment methods for protein. Upon realising that the existing methods of judging protein were far from perfect, they set out to determine the individual amino acid requirements for various ages. Ultimately they established a standard for essential amino acid requirements in adults, which could be matched to various protein sources for both amino acid quantity and ratios.

BV (biological value)

As mentioned, the less nitrogen lost, the more efficiently protein intake is being used by the body. The assessment known as biological value (BV) is based on measuring the rate of excretion of nitrogen produced by a particular type of protein being consumed. On a practical level, BV appears to be the most scientifically accurate yardstick of the potential for protein to be used for lean muscle maintenance and building. On the basis of this measurement, the following is a list of BV ratings for various sources of protein.

whey protein 104
egg white (albumen) protein 88
beef protein 80
soy protein 74
casein 71

It is clear from this chart of the more common supplemental protein sources that by far the highest rate of nitrogen retention is achieved with 100% whey protein. From a dietary standpoint eating whole eggs, as opposed to pure egg whites, will provide a BV of 100; but unfortunately you also get the high fat percentage along with it. Although far below whey, cow's milk rates well at 91, but the problems many bodybuilders have digesting large quantities makes it less practical. Cow's milk is also the most common food allergy, and unless low-fat or skimmed, cow's milk contains larger amounts of saturated fat than is desirable. Rice (59) is superior to wheat (54), but both would be inadequate as an individual source of protein.

Whey is a protein constituent of milk which often gets overlooked in favour of casein, another form of milk protein. From the standpoint of bodybuilding, this is unfortunate, especially when you consider the huge difference in biological value of the two. In addition, other than lactose (milk sugar), casein is typically the cause of adverse reactions to milk products.

Aside from the advantage in terms of potential utilisation, whey also contains proteins such as lactalbumin and immunoglobulins, which are known to be vital for proper immune system function. Of special importance to bodybuilders is the very high concentration of branched chain amino acids (BCAAs) found in whey. The BCAAs (l-leucine, l-isoleucine and l-valine) make up about a third of the protein content of human muscle tissue. Considering that human muscle contains over twenty amino acids, these three BCAAs must be supplemented in disproportionately high amounts compared to the others.

whey protein concentrate

The naturally occurring superiority of whey powder can be further enhanced by technological advances in manufacturing. There are three methods in particular which would considerably enhance the bioavailability of whey protein.

Ion-exchange and micro-filtration are state-of-the-art processes which can be used to create a concentrate of whey protein. These are methods which selectively filter the primary active proteins found in whey. When these processes are employed, the naturally-occurring fat and lactose are extracted out of the finished product. In spite of the fact that whey is derived from milk, these manufacturing techniques exclude all other dairy components as well. Because both micro-filtration and ion-exchange involve the use of low temperature, this preserves the integrity of the proteins, which otherwise can be damaged by excessive heat. The use of hydrolysation is also of great benefit to whey protein bioavailabilty. Hydrolysation involves the use of enzymes which pre-digest the protein into smaller peptides (amino acid chains), thus increasing the ease of digestion, absorption and utilisation.

Taking advantage of the science and technology of protein offers the bodybuilder a huge advantage in terms of the speed and efficiency of lean muscle repair and building. This includes finding the best possible quantity, and quality of the protein being used. At this time, as BV is the superior method of vetting protein, properly manufactured whey protein concentrates represent the highest standard in protein supplementation, and the ultimate choice for the serious bodybuilder.

(taken from MUSCLE NEWS - London 1995)