Protein - Values

MEASURING QUALITIES OF PROTEIN

Lets face it, we are surrounded by protein rich foods everyday. From dairy proteins, to meat, to vegetable sourced proteins such as nuts and seeds and pulses and grains. Are they all equal in quality to each other for building muscle tissue. Well, the answer is of course, no. One of the key questions with regard to the quality of proteins is whether the quality of vegetable proteins are as high as that from meats and dairy foods.

Using the old method of Protein Equivalency Ratios (PER) vegetable proteins do not score very high. But, it is now known that the PER standard bears little relation to human needs for amino acids or to the bioavailability of proteins. A new method of measuring protein quality is therefore now used, known as the Protein Digestibility Corrected Amino Acid Score (PDCAAS).

With the PDCAAS, the quality of food protein is assessed by its content of essential amino acids, the ratios of these amino acids to each other and their bioavailabilty. For example, best quality soy protein is given a PDCAAS of 1.0 which means it is a high quality protein complete in all the essential amino acids.

So what does all of this mean? Well basically, human muscle tissue is not the same as tuna fish muscle, or baboon muscle tissue. This is what makes each animal different in it's dietary requirements for proteins. It was discovered years ago that amino acids are different in quantity to each other and in respect to each other. The structure of amino acids and order of them varies so much from protein to protein. This means that tuna fish protein is an excellent choice for tuna fish to eat to build tuna fish muscle. And so logically speaking, human muscle tissue is ideal for building human muscle tissue with. The amino acids are in the perfect ratio and quantity. Of course we cannot eat masses of human muscle tissue for our needs and so we must assess the quality and availability of existing proteins and their uses for us.

This makes any of those animal and rat studies on proteins virtually irrelevant when it comes to measuring the quality of proteins for humans.

Whey and Casein And Their Biological Value's
All proteins are made up from different ratios of amino acids, the make-up of which determine the proteins Biological Value. This is the measurement of protein quality expressing the rate of efficiency with which protein is used for growth.

Of the whole foods, Egg contains the highest quality food protein known. It is so nearly perfect, in fact, that egg protein is often the standard by which all other proteins are judged. Based on the essential amino acids it provides, egg protein is second only to mother's milk for human nutrition.

On a scale with 100 representing top efficiency, these are the biological values of proteins in several foods:
Protein Ratings

FOOD PROTEIN RATING
Eggs (whole) 100
Eggs (whites) 88
Chicken / Turkey 79
Fish 70
Lean Beef 69
Cow's Milk 60
Unpolished Rice 59
Brown Rice 57
White Rice 56
Peanuts 55
Peas 55

As far as sources of protein created in the lab are concerned, here is a short list of some protein sources you can find in supplements common today. See how they compare to the natural sources listed above:

PROTEIN SUPPLEMENT PROTEIN RATING
Whey Protein Isolate 159
Whey Protein Concentrate 104
Casein 77
Soy 74

As you see, the BV of whey is very very high, but this is wasted if it cannot be absorbed and used by the body in the short period it is in your system. Now take a look at the BV value of casein which is lower than that of Whey. What is unique about casein protein however is the slow digestion rate. Studies that compare whey and casein administered in the workout period inevitably find that whey protein exerts a far stronger anabolic response in this case. However, when casein is administered at other periods the strength gains are twice of those seen with whey. This is because while whey stimulates protein synthesis much more than casein in the short term, casein causes a sustained release of amino acids, preventing muscle breakdown for a more extended period of time . This makes whey the protein of choice for the workout period, with casein preferably added at other times, especially before periods of fasting (such as sleep).

A Word On Soya
Men should avoid soya protein at all costs. This is because there are elements of soya protein, soy isoflavones, that are estrogenic. This lowers your testosterone levels to a point where it can even influence sperm production and efficiency. This can also lead to accumulations of bodyfat and estrogenic side effects in sensitive individuals.

Women should actually seek to increase the levels of soya protein in their diet as it has a very beneficial effect on hormones, recovery rate and bodyfat.

The main sources of protein are meats, fish, milk, eggs, beans, and grains. Egg whites, tuna, turkey, trout, and chicken are among the best.