Americans spend billions of dollars on supplements each year in an attempt to improve their health; however, some experts think that high-protein drinks and kidneys aren't a good combination. There's some evidence that consuming too much protein can increase your risk of developing kidney stones.
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However, for most healthy people, the risk is low. On the other hand, if you have kidney disease, you need to monitor your protein intake. It may be best to avoid protein drinks altogether. Always follow the advice of your doctor or a qualified nutritionist who's familiar with your medical history.
How Your Kidneys Work
To grasp why protein would have an effect on your kidneys, it's helpful to understand how your kidneys actually work. Your kidneys, which are located just below your rib cage on each side of your spine, are one of your body's major filtration organs. Their main job is to filter wastes and any extra fluid out of your blood and then out of your body, through your urine. Your kidneys also filter metabolic byproducts, like acid, to maintain the proper balance of water, salt and electrolytes.
All of your blood passes through tiny filtration vessels called nephrons, which filter your blood, removing the waste products and returning any necessary nutrients to it. When your kidneys are healthy, they remove waste and extra fluid out of the blood, but allow protein to stay. On the other hand, if your kidneys aren't working properly, some of the protein in your blood can make its way into the nephrons and, eventually, into your urine.
High-Protein Drinks and Kidneys
Because the kidneys filter everything that comes into your body and your blood, some experts have speculated that consuming too much protein can put excess strain on the kidneys that increases your risk of developing kidney disease.
The theory is that when you eat too much protein or drink too many high-protein drinks, it increases the amount of urea (a waste product that's leftover over after the protein is broken down) in your blood. As a result, the kidneys have to work harder and, eventually, this increased workload can damage the filtration system of the kidneys, leading to decreased kidney function.
But the science doesn't support the theory. Researchers reviewed more than 2,000 studies on protein and kidney function and published their findings in a report in the Journal of Nutrition in November 2018. After looking over previous evidence, they concluded that consuming a high-protein diet (which they defined as 1.2 to 2.4 grams of protein per kilogram of body weight), had a small effect on the filtration rate of the kidneys, but that effect was trivial in people with healthy kidneys.
Researchers went on to say that this small increase in kidney filtration is a normal adaptive response to eating more protein and that it doesn't increase the risk of developing chronic kidney disease. However, it's important to note that this applies only to those with healthy kidneys. If you already have existing kidney disease and you drink too many protein drinks or consume too much protein powder, side effects are more likely.
Protein and Kidney Disease
If you have chronic kidney disease, kidney function is already decreased. Because of this, you have to be extra careful with how much work you make your kidneys do. Healthy kidneys can handle the extra load of excess protein, but damaged kidneys can't. According to the National Institute of Diabetes and Digestive and Kidney Diseases, eating more protein than you need makes your kidneys work harder, and this can speed up the progression of kidney disease.
On the other hand, a March 2018 report in Chronic Diseases and Translational Medicine notes that a low-protein diet may slow the progression of kidney damage in those with moderate to advanced kidney disease or failure. Another report published in PLOS One in November 2018 had the same findings. Researchers also concluded that eating less protein can help improve heart health in those with chronic kidney disease.
A Word About Kidney Stones
Although the research shows that using high-protein drinks doesn't have a significant, long-term effect on healthy kidneys, a July 2013 report in ISRN Nutrition explains that too much protein may increase your risk of developing kidney stones. When you eat a lot of protein or consume too many high-protein drinks, it increases the amount of acid in your blood. In an attempt to buffer this extra acid, your body pulls calcium out of your bones.
All of this extra acid and calcium passes through your kidneys and increases your risk of developing two different types of kidney stones: calcium kidney stones and uric acid kidney stones. The report notes that, if you have a history of kidney stones, your risk may be even higher.
Kidney stones are uncomfortable, and even quite painful, but for the most part, they resolve on their own without any type of invasive treatment. If you drink protein drinks, you can decrease your risk of developing kidney stones by drinking a lot of water. This reduces the concentration of acid and calcium in your urine and increases your urinary output, which can help prevent the formation of stones.
Read more: How Much Protein Powder Should I Drink?
Other Protein Powder Side Effects
Kidney issues may not be a huge concern with protein drinks, but if you overdo it on the protein supplements or whey protein, side effects that have nothing to do with your kidneys are possible. According to Harvard Health Publishing, eating too much protein may set you up for:
- High cholesterol
- Increased risk of heart disease
- Weight gain
- Constipation and/or diarrhea
However, Harvard Health also notes that these effects may not be caused by the protein directly, but may be connected to eating the wrong types of protein, like a lot of processed meats, that are also higher in unhealthy fats and artificial ingredients.
General Protein Recommendations
There's no definitive answer to how much protein you should eat, since needs may vary based on your age, sex and activity level, but the general recommendation is to stay around 0.8 grams per kilogram of body weight. That means if you weigh 150 pounds, you'd need about 55 grams of protein per day.
Harvard Health Publishing notes that, while your needs may be differ from this general recommendation, it's a good idea not to exceed 2.0 grams per kilogram of body weight, no matter who you are. For a 150-pound person, this would mean staying under 136 grams of protein daily.
However, if you have kidney disease, your goal numbers probably look a little different. Of course, you always want to follow your doctor's recommendations, but the March 2018 report in Chronic Diseases and Translational Medicine notes that a typical low-protein diet for kidney disease provides around 0.6 to 0.7 grams of protein per kilogram of body weight, while a very low-protein diet clocks in at 0.3 to 0.4 grams per kilogram.
- American Kidney Fund: "Protein in Urine"
- National Institute of Diabetes and Digestive and Kidney Diseases: "Eating Right for Chronic Kidney Disease"
- Journal of Nutrition: "Changes in Kidney Function Do Not Differ Between Healthy Adults Consuming Higher- Compared With Lower- or Normal-Protein Diets: A Systematic Review and Meta-Analysis"
- PLOS One: "Effect of Diet Protein Restriction on Progression of Chronic Kidney Disease: A Systematic Review and Meta-Analysis"
- Chronic Diseases and Translational Medicine: "Very Low-Protein Diet to Postpone Renal Failure: Pathophysiology and Clinical Applications in Chronic Kidney Disease"
- Harvard Health Publishing: "When It Comes to Protein, How Much Is Too Much?"
- ISRN Nutrition: "Adverse Effects Associated With Protein Intake Above the Recommended Dietary Allowance for Adults"
- National Institute of Diabetes and Digestive and Kidney Diseases: "Your Kidneys and How They Work"
- Preventive Medicine Reports: "Household Expenditures on Dietary Supplements Sold for Weight Loss, Muscle Building, and Sexual Function: Disproportionate Burden by Gender and Income"
- Mayo Clinic: "Kidney Stones"