Uitspraak van verwijderd op dinsdag 17 januari 2006 om 18:16:
Hoe steekt dit volgens jouw dan in elkaar? Je nieren ondervinden geen last??, of alleen als je genoeg drinkt zoals hier al eerder vermeld werd? Of?? Wel leuk als je ergens op reageert maar leg het dan ook even uit hoe het volgens jouw dan werkt
In mensen met normaal functionerende nieren zijn er nog nooit problemen gevonden bij high protien diets:
Myth #2 "High protein diets are bad for you"
So the average person reads the above information on the protein needs and benefits of a high protein diet but remembers in the back of their mind another myth about high protein intakes. "I thought high protein diets are bad for the kidneys and will give you osteoporosis! " they exclaim with conviction and indignation. So what are the medical facts behind these claims and why do so many people, including some medical professionals and nutritionists, still believe it?
For starters, the negative health claims of the high protein diet on kidney function is based on information gathered from people who have preexisting kidney problems. You see one of the jobs of the kidneys is the excretion of urea (generally a non toxic compound) that is formed from ammonia (a very toxic compound) which comes from the protein in our diets. People with serious kidney problems have trouble excreting the urea placing more stress on the kidneys and so the logic goes that a high protein diet must be hard on the kidneys for healthy athletes also.
Now for the medical and scientific facts. There is not a single scientific study published in a reputable peer - reviewed journal using healthy adults with normal kidney function that has shown any kidney dysfunction what so ever from a high protein diet. Not one of the studies done with healthy athletes that I mentioned above, or other research I have read, has shown any kidney abnormalities at all. Furthermore, animals studies done using high protein diets also fail to show any kidney dysfunction in healthy animals.
Now don't forget, in the real world, where millions of athletes have been following high protein diets for decades, there has never been a case of kidney failure in a healthy athlete that was determined to have been caused solely by a high protein diet. If the high protein diet was indeed putting undo stress on our kidneys, we would have seen many cases of kidney abnormalities, but we don't nor will we. From a personal perspective as a trainer for many top athletes from various sports, I have known bodybuilders eating considerably more than the above research recommends (above 600 grams a day) who showed no kidney dysfunction or kidney problems and I personally read the damn blood tests! Bottom line? 1-1.5 grams or protein per pound of bodyweight will have absolutely no ill effects on the kidney function of a healthy athlete, period. Now of course too much of anything can be harmful and I suppose it's possible a healthy person could eat enough protein over a long enough period of time to effect kidney function, but it is very unlikely and has yet to be shown in the scientific literature in healthy athletes.
So what about the osteoporosis claim? That's a bit more complicated but the conclusion is the same. The pathology of osteoporosis involves a combination of many risk factors and physiological variables such as macro nutrient intakes (carbs, proteins, fats), micro nutrient intakes (vitamins, minerals, etc), hormonal profiles, lack of exercise, gender, family history, and a few others. The theory is that high protein intakes raise the acidity of the blood and the body must use minerals from bone stores to "buffer" the blood and bring the blood acidity down, thus depleting one's bones of minerals. Even if there was a clear link between a high protein diet and osteoporosis in all populations (and there is not) athletes have few of the above risk factors as they tend to get plenty of exercise, calories, minerals, vitamins, and have positive hormonal profiles. Fact of the matter is, studies have shown athletes to have denser bones than sedentary people, there are millions of athletes who follow high protein diets without any signs of premature bone loss, and we don't have ex athletes who are now older with higher rates of osteoporosis.
In fact, one recent study showed women receiving extra protein from a protein supplement had increased bone density over a group not getting the extra protein! The researchers theorized this was due to an increase in IGF-1 levels which are known to be involved in bone growth. Would I recommend a super high protein diet to some sedentary post menopausal woman? Probably not, but we are not talking about her, we are talking about athletes. Bottom line? A high protein diet does not lead to osteoporosis in healthy athletes with very few risk factors for this affliction, especially in the ranges of protein intake that have been discussed throughout this article.
Article References
1 Lemon, PW, "Is increased dietary protein necessary or beneficial for individuals with a physically active life style?" Nutr. Rev. 54:S169-175, 1996.
2 Lemon, PW, "Do athletes need more dietary protein and amino acids?" International J. Sports Nutri. S39-61, 1995.
3 Tarnopolsky, MA, "Evaluation of protein requirements for trained strength athletes." J. Applied. Phys. 73(5): 1986-1995, 1992
4 Phillips, SM, "Gender differences in leucine kinetics and nitrogen balance in endurance athletes." J. Applied Phys. 75(5): 2134-2141, 1993.
5 Tarnopolsky, MA, 1992.
6 Carroll, RM, "Effects of energy compared with carbohydrate restriction on the lipolytic response to epinephrine." Am. J. Clin. Nutri. 62:757-760, 1996.
7 Bounus, G., Gold, P. "The biological activity of undenatured whey proteins: role of glutathione." Clin. Invest. Med. 14:4, 296-309, 1991
8 Bounus, G. "Dietary whey protein inhibits the development of dimethylhydrazine induced malignancy." Clin. Invest. Med. 12: 213-217, 1988
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