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Protein and Kidneys

How much protein is too much?

Graphic showing link between protein and kidneys

Despite all the finer points of eating plenty of protein, including making it easier to build and hold onto muscle mass and making meals more satiating, the safety of habitually consuming high amounts of this macro has been questioned. Mainly, those questions concern the link between protein and kidneys.

The metabolites of protein digestion—including ammonia—are among the compounds that your kidneys are responsible for removing from the body. That’s why it’s been proposed that consuming too much protein can overwork this organ leading to increased strain and, eventually, a downturn in functioning.

Thankfully, a recent study in The American Journal of Clinical Nutrition can help most protein lovers rest easy. The research assessed the association between daily protein intake and all-cause mortality among 27,604 American adults with varying degrees of kidney functioning, from highly impaired to fully operational. While those with impaired kidney functioning were found to have a greater risk of mortality with higher daily total protein intake (1.4 grams of protein per kilogram body weight or more each day), especially when protein came from meat, this was not the case for the majority of people with normal kidney functioning.

In fact, the researchers discovered in individuals with fully functional kidneys a low daily protein intake (less than 0.6 grams/kg/body weight) was associated with an increased risk for all-cause mortality. The take-home message here is that while protein restriction appears to be appropriate for the treatment of existing kidney disease, people with healthy kidneys should not fret that going bigger on this macro will have a detrimental impact on this organ.

See also: Protein Is Not Necessarily Your Kidneys’ Nemesis

Matthew Kadey, MS, RD

Matthew Kadey, MS, RD, is a James Beard Award–winning food journalist, dietitian and author of the cookbook Rocket Fuel: Power-Packed Food for Sport + Adventure (VeloPress 2016). He has written for dozens of magazines, including Runner’s World, Men’s Health, Shape, Men’s Fitness and Muscle and Fitness.

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November-December 2020 IDEA Fitness Journal

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