Dieet en aankomen

quote:

Op maandag 4 juli 2005 18:48 schreef Mr.J het volgende:
Ja welke precies.

Ik heb namelijk zelf absoluut geen kennis van de biochemie van het menselijk lichaam en het daarbijhorende endocriene systeem waar ook je HPTA onder valt.

quote:

Op maandag 4 juli 2005 18:48 schreef Mr.J het volgende:
Ja welke precies.

Ik heb namelijk zelf absoluut geen kennis van de biochemie van het menselijk lichaam en het daarbijhorende endocriene systeem waar ook je HPTA onder valt.

quote:

Op maandag 4 juli 2005 09:30 schreef Catch22- het volgende:
Vis is gezond, helpt niet veel denk ik

quote:

Op woensdag 6 juli 2005 11:58 schreef Mr.J het volgende:

Anyway, de beste meneer in kwestie mag ipv rond te neuzen op het voedingscentrum wat echte info zoeken. Voor zover ik weet zit je onder de 6 a 7 gram eiwitten per kg lichaamsgewicht nog veilig.

quote:

Op woensdag 6 juli 2005 12:02 schreef Isabeau het volgende:

[..]

Gelukkig dat er fokkers zijn die het beter weten dan het malafide Voedingscentrum

quote:

Protein and amino acid requirements of adults: current controversies.

Millward DJ.

Centre for Nutrition & Food Safety, School of Biomedical and Life Sciences, University of Surrey, Guildford, Surrey, United Kingdom.

Protein intakes vary widely but costs and benefits of such variation is a long standing unresolved issue. The wide range of reported values for the minimum protein intake for N equilibrium in adults, i.e. 0.39 to 1.09 g/kg is best explained by an Adaptive Metabolic Demands model in which metabolic demands include amino acid oxidation at a rate varying with habitual protein intake and which changes slowly with dietary change. Thus within the reported data the true minimum requirement intake, the lowest values in the range at intakes approaching the Obligatory Nitrogen Loss, allows only fully adapted subjects to achieve N equilibrium. The higher values reflect incomplete adaptation. (13)C-1 leucine tracer balance studies of this model show (a) a fall with age in apparent protein requirements, (b) better than predicted efficiency of wheat protein utilization, and (c) controversially, lower lysine requirements than other workers, consistent with new evidence of de novo synthesis of lysine from urea salvaged by large bowel microflora. The main implication of the requirements model for athletes on high protein diets is increased exercise induced amino acid oxidation and risk of loss of body N when such high intakes are not maintained.

Publication Types:
Review
Review, Tutorial

PMID: 11897889 [PubMed - indexed for MEDLINE]

quote:

Nutritional Myths that Just Won't Die: Protein!

By Will Brink

"Nutritional Myths that Just Won't Die: Protein!"

When it comes to the topic of sports nutrition there are many myths and fallacies that float around like some specter in the shadows. They pop up when you least expect them and throw a monkey wrench into the best laid plans of the hard training athlete trying to make some headway. Of all the myths that surface from time to time, the protein myth seems to be the most deep rooted and pervasive. It just won't go away. The problem is, exactly who, or which group, is perpetuating the "myth" cant be easily identified. You see, the conservative nutritional/medical community thinks it is the bodybuilders who perpetuate the myth that athletes need more protein and we of the bodybuilding community think it is them (the mainstream nutritional community) that is perpetuating the myth that athletes don't need additional protein! Who is right?

The conservative medical/nutritional community is an odd group. They make up the rules as they go along and maintain what I refer to as the "nutritional double standard." If for example you speak about taking in additional vitamin C to possibly prevent cancer, heart disease, colds, and other afflictions, they will come back with "there is still not enough data to support the use of vitamin C as a preventative measure for these diseases," when in fact there are literary hundreds of studies showing the many benefits of this vitamin for the prevention and treatment of said diseases.

And of course, if you tell them you are on a high protein diet because you are an athlete they will tell you, "oh you don't want to do that, you don't need it and it will lead to kidney disease" without a single decent study to back up their claim! You see they too are susceptible to the skulking myth specter that spreads lies and confusion. In this article I want to address once and for all (hopefully) the protein myth as it applies to what the average person is told when they tell their doctor or some anemic "all you need are the RDAs" spouting nutritionist that he or she is following a high protein diet.

[..]

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.

[..]