Negative Effects Of Protein
So why all the fuss about the ingestion of too much protein? So far, we've seen protein's positive effects and that it can be beneficial for hypertrophy of the muscle complex. A common argument raised is that excessive protein, as described above, can cause a variety of body ailments--such as kidney and heart disease, constipation, and osteoporosis. These are often cited as the main reason one would want to steer clear of a diet rich in protein (4).
The average person reading about this might want to jump on the anti-protein bandwagon, but what they don't realize is that these studies often mislead. For starters, the negative health claims of kidney disease resulting from a high protein diet have used information gathered from studies done on patients with existing kidney problems. Kidneys are responsible for excretion of the urea formed from ammonia (a very toxic compound) which comes from the protein in our diet.
People with kidney problems already have trouble excreting urea, and this leads to more stress on the kidneys. The logic goes that strength trainers, bodybuilders, weightlifters and athletes who eat a high protein diet are doomed to suffer from future kidney problems.
Furthermore, there don't seem to be any peer-reviewed studies done on healthy athletes, strength trainers, weightlifters or bodybuilders showing that kidney problems are a result of a high protein diet.
As for the claims of osteoporosis in these groups, it's hard to believe that they cancel the benefits of exercise. Exercisers have strong, healthy bones that are denser in nature, and studies have shown that exercise promotes this condition. Negative results may be seen in those who are sedentary and consume a high protein.
For the most part, however, one cannot simply isolate one factor and claim that this is a reason for a health problem such as this; the pathology of osteoporosis involves far more than one variable. Things such as heredity, genetics, micro and macro nutrient intake, exercise etc., when taken together, are far more responsible than simply applying the blame to one area.
Constipation is also used as an argument because many nutritionists and dieticians claim that diets high in protein are low in fiber. Without enough bulk the digestive system can slow down to a snail's pace. Simply choosing the right foods such as fibrous vegetables, starchy breads, pastas and drinking plenty of water will remedy this problem. Heart disease may result from a high intake of animal, but, as mentioned earlier, knowing how to use variety in one's diet will help eliminate worry about this kind of problem. Low and no-fat dairy products, fish and lean cuts of meat and chicken are good choices which considerably lower the risk of heart disease.
High protein intake, as we've seen, is not the evil it's made out to be. A protein deficiency will reveal itself because strength and muscle mass will decline. What are the signs of taking too much? Inflammation of the kidneys (lower back pain) and feelings of malaise are symptoms to watch for. Most of the time the body does a good job of sorting and using protein, so most people will not run into this problem.
But even if protein intake is increased it means eating multiple meals throughout the day since the experts have said we can only digest 25-30 grams of protein per sitting. The small intestines can digest as much as 500-700 grams of protein (5) keeping in mind proteins functions do include other things other than soft tissue repair. New research has shown now that the body may in fact be able to handle much more protein in a sitting (6). This obviously shows us that individuals of varying bodyweights can take in much more than the 25-30 gram figure the experts have held us to for so long.
Conclusion
Hopefully you've been convinced that a high protein intake is not "evil." Protein intake ranging from 1.4 grams of protein per kilogram of bodyweight to one gram per pound or more can be beneficial for an individual involved in an intense training program. Protein has been typecast as something that will make you big and strong, but muscle growth is not controlled by the level of protein one takes; rather it is the growth demand caused by intense training or stress that will ultimately determine how much protein one should take in.
Dr Michael Colgan says, "No one ever grew an ounce of muscle from simply gulping protein. Muscles grow from pushing poundage-period." Some trainers have testified that they've done just fine by taking in small amounts of protein, but the question to them is, how much greater would the results have been if they had increased the protein requirement to meet the demands of the exercise?
We don't have to consume an extraordinarily amount of protein, but the proof of the pudding is that taking more than the RDA when exercising is not only safe, but beneficial.
References
(4) A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women. DE Sellmeyer, KL Stone, A Sebastian, SR Cummings. American Journal of Clinical Nutrition, 2001, Vol 73, Iss 1, pp 118-122.
(5) Guyton M.D., Arthur C. Human Physiology and Mechanisms of Disease; 1992.
Arnal MA, Mosoni L, Boirie Y, Houlier ML, Morin L, Verdier E, Ritz P, Antoine JM, Prugnaud (6) J, Beaufrere B, Mirand PP. Protein pulse feeding improves protein retention in elderly women. American Journal of Clinical Nutrition. 1999 Jun;69(6):1202-8.
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