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Can High-Protein Diets Damage Your Kidneys?

(Source: www.forbes.com)

Here’s a quote that’s been floating around the Internet: “When life gives you lemons, you ask for something higher in protein.”

While it’s not clear who originated the quote (probably not a pasta maker or a bread baker), the quote certainly highlights the recent popularity of high-protein diets such as the Dukan, the Atkins, the South Beach, the Paleo and the Ketogenic diets. The weight loss for high-protein diets hinges in large part on the theory that protein can help you eat less by making you feel full earlier and boosting your metabolism. Although there is evidence that high-protein diets may help with short-term weight loss, the jury is still out on whether high-protein diets can really lead to longer-term and sustainable weight loss. Also, eating too much protein is not without its risks. An article just published in the New England Journal of Medicine reviewed the scientific evidence on what the amount of protein in your diet can do to your kidneys.

For the article, Kamyar Kalantar‑Zadeh, M.D., M.P.H., Ph.D. of the University of California-Irvine School of Medicine and Denis Fouque, M.D., Ph.D. from the Université Claude Bernard Lyon summarized what is known from studies in animals and humans. Think of your kidneys as the filtering system for your blood. Your blood transports waste products from throughout your body to your kidneys. Your kidneys then pull these waste products out of your blood and excrete them from your body as urine.

As Kalantar‑Zadeh and Fouque explained, studies in animals (mainly rats) have found that more protein in their diets and thus in their blood seems to affect the blood flow within their kidneys and as a result increases the rate at which their kidneys filter blood. The concern is that over time this increased rate may damage the kidneys. Too much damage to the kidneys means that waste products build up in the body, which, like letting trash pile up in your house, will eventually be fatal without a new kidney. Indeed, in rats, consuming more than 1.5 g of protein per kilogram of body weight per day may increase the rate at which the kidneys filter blood.

While studies in humans have not fully confirmed this finding, some human studies have suggested that moderating the amount of protein in your diet may play a role in preventing kidney disease. For example, a study published in the Journal of Renal Nutrition found that people who reported eating more red and processed meats were more likely to develop chronic kidney disease.

Moreover, keep in mind that, according to the National Institute of Diabetes and Digestive and Kidney Diseases, 14% of people in the United States have chronic kidney disease, most commonly from high blood pressure or diabetes. This number may rise as the rates of obesity (which can then lead to high blood pressure and diabetes) continue to rise. As the review article indicated, there is some scientific evidence that restricting the intake of protein can help slow the progression of kidney disease. So before you start on any high-protein diet, you may want to check with your doctor to make sure your kidneys are functioning normally.

Since many of these high-protein diets have not been studied long or extensively enough, it isn’t completely clear what the longer-term effects on your kidneys of these diets may be. But the current scientific evidence suggests that there may be risks, even if you are not a rat (in the species sense that is). As with most things in life, moderation in your diet is key. While high may be good for stock returns and ferris wheels, too much of anything in your diet may not be good.

More Info: www.forbes.com

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