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Excess protein can overload the kidneys, especially if prolonged over time.
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Athletes and active people can benefit from increased protein intake, but be careful not to overdo it.
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Keeping a balance, as always, is the best advice for long-term health.
Protein is an essential component for anyone who plays sports or wants to stay fit. It is no coincidence that sports nutrition experts recommend them because of their role in rebuilding muscle fibers stressed by exercise. In short, not taking them would lead to a deterioration of the muscles (which would have no raw material to rebuild themselves) and of physical performance, as well as being inadvisable because it would unbalance the nutritional intake.
There is, moreover, no reason not to take any, to be honest. If anything, the problem is the opposite, that is, overdoing it: what, in short, is the limit beyond which not to go? We could start by looking for it in the kidneys, which are deputed to the metabolism of proteins, since they remove waste products derived from their catabolism. Kidney specialists, namely nephrologists, however, warn against consuming too much of them, especially in the long run. The warning is about overloading the kidneys and the irreversible damage that could result. Is it right to worry and to what extent?
Can too much protein damage the kidneys?
The first warning about excessive protein consumption and the risk to kidney health came in 1982, when nephrologist Barry Brenner published a study in the New England Journal of Medicine. What he showed was that a diet high in protein can accelerate the decline of kidney function, especially if maintained for long periods.
The thesis focused on the fact that when we consume protein, it is broken down into amino acids, which are then used for muscle repair. Those not used, however, are converted into energy, generating a waste substance called urea, which the kidneys must filter out. The greater the protein consumption, the more urea is produced, and the greater the workload for the kidneys.
Eating a lot of protein actually increases renal filtration work, since the kidneys have to work harder to eliminate waste. In the long run, this could create an overwork that damages their ability to filter properly, leading to chronic disease.
What nephrologists say
Nephrologists are concerned that, even in healthy people, the constant increase in pressure on the kidneys may gradually deteriorate the filtering structures, leading to a progressive deterioration of kidney function. This prospect may be remote for those who take a little more than there is in the food they usually consume (supplementing, in short) but is potentially critical for those athletes-such as bodybuilders-who follow high-protein diets for long periods of time.
The problem seems to involve more those who already have problems related to renal function, while it is less apparent for those with healthy kidneys. In fact, many studies on healthy individuals do not show a direct link between high protein intake and kidney damage. As a cautionary note, however, some nephrologists warn against diets too high in protein for a prolonged time, suggesting that current research findings may not be unequivocal enough in identifying links between excess protein and kidney damage only because of gaps in the research and not because the problem does not exist. When in doubt, in short, it is best not to overdo it (advice that is always good, anyway!).
And what do sports nutritionists say about it?
Sports nutritionists are less concerned. The International Society of Sports Nutrition (ISSN) argues that there is insufficient evidence to say that high protein intake may pose a health risk to healthy, active individuals. For example, recent studies have shown that athletes who consume up to 4.4 grams of protein per kilogram of body weight per day show no signs of kidney damage.
Nevertheless, some critics of this approach point out that many studies in this regard consider observation intervals to be too limited and on small samples, which may not be sufficient to observe any long-term adverse effects. In short, it is not only important to show that there does not seem to be any damage in the short term: it is the long term that is of most concern, but in order to get more precise answers, it is necessary to extend the research to time frames of years if not decades and on thousands of people, kidney healthy or not.
How much protein is too much?
And we know you wanted to get here but the answer is not so simple. The recommended daily intake is about 0.8 grams per kilogram of body weight, which for a 70-kilogram person is equivalent to about 56 grams of protein per day, or a couple of 140-gram cans of tuna each.
Many nutritionists actually suggest that athletes and active individuals may get between 1.4 and 2.0 grams per kilogram. Some studies even suggest that higher amounts may give additional muscle-building benefits, although the evidence is not yet conclusive. Those who consume about 1.0 to 1.5 grams of protein per kilogram of weight per day-that is, the average person, who does not follow any particular dietary regimen to perfect athletic performance-might indeed benefit from increased protein intake, especially if distributed evenly throughout the day. The limit, however, seems to be 3-4 grams per kilogram, beyond which there would be no significant benefit, and, in some cases, indeed there could be potential risks.
Virtue lies in the middle
In short, science seems to have not yet made a final judgment, so all that remains is to rely on reasonable balance. Which one? The one that allows you to rebuild muscle fibers, of course. But how to tell if you’re replenishing enough? The test is training and competition: if you feel fatigued all the time or your muscles seem not to be doing their job, not functioning to their full potential, or even losing mass, it’s likely a protein deficiency.
A moderate protein intake that supports muscle growth and overall health, without overdoing it, is the safest strategy in this case. If you do not have kidney problems in short, you may not have to worry too much about overdoing it, with the understanding that it is always a good idea to consult a doctor or nutritionist to assess what is best for you.
(Via Outside)