Friday, February 02, 2007

Protein in our diet

Protein Series PART I
Understanding the Importance & Differences in Proteins.

by Jose Antonio, Ph.D. & Melinda Mergen

Protein is needed by every kind of every cell in your body to replicate, repair and often times grow. Learn the basics on the different kinds, how it works, the effects it has on the human body, and why it is so important to understand the true facts about protein.

What is protein anyway?
Just as glucose is the building block of glycogen; amino acids are the building blocks of proteins. Proteins are arguably the most important component of every cell in the human body. They're involved in the formation of contractile tissue and muscle and, they make up a large part of the structural component of cells. They are a part of enzymes, antibodies, blood; the list goes on. You name it, protein is a part of it. The main function of protein is to provide the necessary amino acids for maintaining an anabolic growth or a weight-stable state. Recent data shows that additional protein also promotes recovery and performance during exercise.(1,2)

How much protein should you consume?
Suffice it to say that the RDA of 0.8 grams per kilogram of body weight per day is grossly inadequate for anyone whose activity levels exceed that of a La-Z-Boy recliner. Even though muscle protein degradation or breakdown increases during exercise, there is a significant increase in muscle protein synthesis for at least 24 hours after either resistance or endurance exercise. If you are not getting adequate protein during this time, then it would make sense that you will probably not gain lean body mass. We suggest 1 gram of protein daily per pound of body weight should be consumed daily, spread throughout the day's meals.

How Much protein can I consume at 1 sitting?
Great question! Unfortunately, the scientific answer is not known. But I'll give you Midwestern, common sense answer. Would your 75-year-old grandma and the 250 lb, 25-year-old mixed martial arts fighter have the same limitations when it comes to digesting and absorbing protein. Obviously, the fighter needs more protein to assist with recovery and repair of muscles.

In all fairness though, there are studies in which 30 grams of protein are fed to subjects; and this amount produces a tremendous rise in blood amino acid levels. I'd imagine that 30 grams of protein per meal is a good starting point. If you eat 30 grams at each meal and you eat 6 times daily, that's about 180 grams of protein. For most 'average-weight' individuals, that should suffice. But imagine if you're a 300lb football player or a bodybuilder? You would either have to eat more protein per sitting or just eat more meals.

Now most of us are probably wondering how to fit all of that in? There is an answer to this problem. Consume meal replacement powders as a protein supplement when you can not get a high quality serving of 4 to 8oz (or between 20g to 40g) of protein from the foods you eat at a meal.

Protein and bone healthAccording to one study, protein intake does not contribute to the wide variability in calcium absorption efficiency.(3) Or put another way, eating protein probably has no effect on bone mineral content. Another investigation stated verbatim that, "several recent epidemiological studies demonstrate reduced bone density and increased rates of bone loss in individuals habitually consuming low protein diets."(3-5) So one might argue that low protein intake is the culprit. Either way, it would be wise to consume both adequate protein and calcium to maintain lean body mass and reduce body fat.

Adding Protein to Sports Drinks
In a study that compared a traditional sports drink (water, carbohydrates, and electrolytes) versus a sports drink that contained protein, they found that cyclists rode 29% to 40% longer when they consumed the sports drink with protein than the one without. Also, peak, post-exercise plasma (CPK or creatine phosphokinase) levels, an indirect measure of muscle damage, were 83% lower after consuming the sports drink plus protein. So don't believe the baloney about protein dehydrating you; if it did, these cyclists would not have performed better! Even a small amount of 3 to 6g during exercise may do wonders for you.(1)

Which Types of Protein are Good?
Are amino acids a sufficient replacement for protein? Stay tuned for future newsletters when we discuss the pros and cons as well as different sources of soy, whey, casein, and other protein sources!

Additional Reading and Information
Effects of a Carbohydrate-protein Beverage on Cycling Endurance and Muscle Damage.
Protein, Calcium Metabolism, and Skeletal Homeostatis
Please click here for References and additional Reading Material.


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