Doctors Warn Athletes About Eating Too Much Protein
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Protein has at all times been my protected house within the food regimen wars. Because the pendulum swings forwards and backwards between “carbohydrates are going to kill you” and “fat is going to kill you,” everybody agrees that protein is sweet to your muscle groups, satiating, and non-lethal. Everybody besides nephrologists, that’s.
Again in 1982, a nephrologist—that’s, a kidney physician—named Barry Brenner, co-author of one of many definitive textbooks on nephrology, printed a paper in the New England Journal of Medicine suggesting that consuming an excessive amount of protein over an extended time period would possibly overwork the kidneys and ultimately result in power kidney illness and even kidney failure. This concept has been hotly debated ever since, with opinions loosely settling into two distinct camps: nephrologists assume an excessive amount of protein is an issue, and sports activities diet researchers assume it isn’t.
As somebody who pays lots of consideration to the sports activities diet literature and little or no consideration to the most recent nephrology information, I haven’t anxious a lot about Brenner’s speculation. However a latest overview paper by three nephrologists in Sports Medicine—in my world, in different phrases—caught my consideration.
Alberto de Lorenzo of HM Sanchinarro College Hospital in Madrid, together with two colleagues, argues that power kidney illness could be “the real finish line” for athletes and bodybuilders on a high-protein food regimen. Given all of the articles I’ve written concerning the joys of protein, I figured it was price digging into.
Why Kidney Specialists Fear About Too Much Protein
Many of the protein you eat is damaged down into amino acids that are then used to construct or restore muscle. If there’s any further protein, will probably be burned to supply vitality. One of many byproducts of burning protein is a waste product known as urea. The job of filtering out waste merchandise like urea out of your bloodstream is dealt with by your kidneys, which ship the undesirable waste to be excreted in your urine. The extra protein you eat, the extra urea you’ll produce—and, consequently, the more durable your kidneys must work.
It’s moderately properly established that consuming extra protein will result in a rise in kidney filtration price, presumably to deal with the upper waste load. That is accompanied by dilation of the blood vessels resulting in the kidney and a rise within the stress on the filtering items. Equally, consuming much less protein reduces the filtration price. Because of this, individuals who have already got power kidney illness however aren’t on dialysis are sometimes suggested to maintain their protein consumption comparatively low.
What some nephrologists concern is that, even in individuals with wholesome kidneys, this elevated blood circulation and stress will ultimately injury the fragile filtering constructions within the kidney—which in flip will power the remaining kidney constructions to work even more durable, triggering a kidney dying spiral.
The proof for this sequence of occasions is evident for individuals (and animals) who have already got kidney issues. However it’s principally non-existent for individuals with regular kidney perform. Meaning it turns into a query of weighing completely different sorts of oblique proof.
Why Sports activities Nutritionists Don’t Fear About Protein
The Worldwide Society of Sports activities Vitamin, in its official position stand on protein and train, is unequivocal: “no controlled scientific evidence exists indicating that increased intakes of protein pose any health risks in healthy, exercising individuals.” Furthermore, the place stand cites a collection of research led by Jose Antonio, the cofounder of the ISSN, through which athletes consumed as a lot as 4.4 grams of protein per kilogram of physique mass every day, greater than 5 instances the really useful day by day allowance of 0.8 g/kg/day, with none in poor health results.
De Lorenzo and his colleagues aren’t impressed by these research, or by the bigger physique of research in wholesome non-athletes. The pattern sizes had been small, and their durations ranged from six weeks to a yr, which could not be lengthy sufficient to watch a decline in kidney perform. The assessments used to estimate kidney filtration price are designed to be used with kidney illness sufferers, and are much less correct in individuals with wholesome kidneys, notably if they’ve excessive muscle mass. There have been no true low-protein-diet management teams. The authors have ties with sports activities diet firms that promote protein dietary supplements, and none of them had been nephrologists.
These critiques are all price contemplating, however you must weigh them towards the energy of no matter different proof is accessible—which, on this case, will not be a lot. I dug up a number of of the person research and meta–analyses to have a look at extra intently, and my normal impression was that it was principally a Rorschach check. Relying on which outcomes you take a look at and what threshold you utilize to outline a clinically vital change, you possibly can persuade your self that top protein consumption has a powerful impact on kidney perform or has no impact on kidney perform.
How Much Protein is “Too Much”?
Half a century after Brenner’s authentic warning, I nonetheless don’t see any compelling proof that wholesome individuals want to fret about consuming an excessive amount of protein. I can’t rule it out, although. So it’s price contemplating some numbers. The protein RDA is 0.8 g/kg/day, which for a 150-pound individual works out to about 55 grams of protein per day. That’s a few 5-ounce cans of tuna.
De Lorenzo’s paper defines a “high-protein diet” as greater than 1.5 g/kg/day. The ISSN means that “the majority of exercising individuals” ought to purpose for 1.4 to 2.0 g/kg/day, although it notes some “preliminary evidence” that larger doses even above 3 g/kg/day would possibly assist construct muscle. A major meta-analysis in 2018 concluded that muscle- and strength-building beneficial properties max out at round 1.6 g/kg/day on common.
The average daily protein intake amongst People, as of 2015-2016, was 97 grams for males and 69 grams for ladies. Relying on weight, that’s within the vary of 1.0 to 1.5 g/kg/day. In broad strokes, then, I think that the common individual may most likely nonetheless profit from upping their protein consumption.
Specifically, specializing in getting extra protein all through the day reasonably than cramming in an enormous load at dinner would possibly (although not essentially) assist construct extra muscle. However I’d pause earlier than pushing too far into the extremes, like 3 or 4 g/kg/day—not as a result of there’s sturdy proof that it’s harmful, however as a result of it’s conceivable that there could be downsides and never clear that there are vital upsides.
Because it occurs, that balancing act is clear in another new study that was printed final month taking a look at protein consumption and mortality in older adults who have already got power kidney illness—in different phrases, the group that we all know can be harm by an excessive amount of protein. The outcomes had been the other of what you’d count on: the extra protein topics ate, the much less probably they had been to die in the course of the research. Increased protein consumption is related to all types of interconnected advantages in older individuals: extra muscle, stronger bones, much less frailty, decrease charges of coronary heart illness, and so forth. On this cohort, these advantages outweighed no matter theoretical hurt protein would possibly inflict on the kidneys. For muscle-challenged endurance athletes like me, that’s a message to bear in mind.
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