A Primer on Protein (supplement overview)

Posted in: Sports Nutrition  on Tuesday, August 19, 2008
If you want to look good, feel great, build muscle, and keep your immune system running at its best, you need adequate amounts of protein. Take away the fat, and virtually everything inside our bodies is made up of it. Even hair and nails.

Because protein is the building block for human tissue, it’s needed to keep skin supple, internal organs functioning properly, muscles repairing and rebuilding, and even in the production of healthy blood.

Given its essential nature, you’d think that evaluating protein requirements would be fairly straightforward. But few topics in fitness, bodybuilding, and strength training arouse as much heated debate. Making it even more confusing to the consumer is that everyone claims to be an expert.

How Much
Go to the real experts, however, and you can toss out the current Recommended Daily Allowances, as suggested by the Food and Drug Administration. That recommendation is .8 grams of protein per day, per kilogram of bodyweight (.36 grams per pound).

But that recommendation is inadequate, according to the world’s most referenced protein researcher, unless you’re absolutely sedentary. Testing athletes in a variety of sports, Dr. Peter Lemon, chairman of the Exercise Nutrition Department at the University of Western Ontario, Canada, found that their requirements are about double that, from 1.5 to 1.6 grams of protein (or .68 to .73 grams per pound).

The dangers of taking in excess protein are almost always overstated, say both Lemon and Kleiner. "Excess is simply excreted," says Kleiner. "Unless the person has a pre-existing kidney condition, won’t drink water, is old, or has some unusual disturbance in their ability to digest protein, we simply don’t see problems. It’s a myth."

The Right Protein
Not all proteins are created equal, however. A variety of systems have been used to determine the quality of a protein and its bioavailability (how well it’s used). The merits and disadvantages of each of these systems have been debated endlessly.

Most of these arguments center on what a "perfect" protein is. And much of the research to support the debates have been drawn from animal studies, rather than from human ones. But as we return to people-based studies, a few things are clear:

• Human beings can thrive on a variety of protein sources. You can eat animal-based proteins, vegetarian proteins, or a combination of the two, and be just fine.

• Early research into vegetarian protein suggested that the amino acids – the constituent parts of protein – in human muscle did not correspond well to the proportion of amino acids in vegetarian protein sources. That’s true; the amino acid lysine is in short supply from veggie sources.

• Other concerns centered on getting enough of the essential amino acids, those that the body needs but cannot manufacturer itself. Despite some vegetarian partisan claims to the contrary, the proportions of the essential amino acids within vegetarian sources vary far more widely that in most animal proteins. (Additionally, some vegetarian protein sources contain very high levels of carbohydrates.)

• Over the period of a day, if those essential amino acids are not furnished in adequate amounts, protein synthesis within the body starts to fail. Several human studies have shown that the effects of severe amino acid imbalance may take more than a few months to show up, however.

As for those endlessly esoteric claims about various special factors in certain proteins, polypeptide chains, and the like? "It usually just means someone’s broken down the protein before your body can," observes Kleine r. "Unless something is wrong with your basic digestion, it doesn’t make any difference , other than you’ll spend a few less calories in digestion." And perhaps a few more dollars when you don’t need to.