Protein is important to meeting almost any fitness goal. It promotes the growth of lean muscle mass. It can also aid in weight loss. This leads many clients to increase their protein intake via powders and shakes.

Part of being a personal trainer involves answering questions about protein intake. And one question that pops up from time to time is whether drinking a protein shake will increase one’s kidney stone risk.

Addressing this concern requires first understanding how the kidney works. It’s also helpful to know what can contribute to stone formation. Let’s get into each of these now.

The Kidney and Protein

The kidney is responsible for removing toxins from the body. To do this, it filters these toxins into the urine, where they can be excreted.

Typically, people are born with two kidneys. Although, some are born with just one. Others have one kidney because they’ve donated the other to someone with a kidney problem that prevents theirs from functioning effectively. You can survive with only one kidney. You just have to be mindful to drink a lot of water and watch your intake of protein.

The reason for this is that protein places more stress on the kidney. If kidney function is compromised, this organ may not be able to process all the protein consumed. This can cause a buildup in the blood. Some research connects high protein diets with increased hypertension risk. Other studies indicate that if protein consumption is elevated long-term, it may also increase one’s risk of chronic kidney disease.

How Kidney Stone Formation Occurs

When there is too much waste in the blood and not enough liquid, a kidney stone can form. A kidney stone starts as a small group of crystals. Over time, it can grow bigger. If it becomes too big, it can cause a blockage in the urinary tract. This can result in pain, vomiting, nausea, and fever. Some people with kidney stones also experience blood in the urine.

The National Kidney Foundation explains that there are four different types of kidney stones. They are:

• Calcium oxalate kidney stone. This is the most common and occurs when calcium and oxalate combine. Not drinking enough fluids and low calcium intake can lead to calcium oxalate stones.

• Uric acid kidney stone. Uric acid stones are also common. This stone occurs when purine intake is increased, causing the body to produce more monosodium urate. If a family member is prone to uric acid kidney stones, you may be more prone to them too.

• Struvite kidney stone. This stone is less common and can occur due to an upper urinary tract infection. 

• Cystine kidney stone. This is the rarest type of stone and is caused by a cystinuria disorder. This stone tends to be genetic. A cystine stone also tends to be larger than other stone types. 

Can Protein Powder Cause Kidney Stones?

If a high protein diet can impact kidney function, does this mean that protein shakes will increase your risk of forming stones? Unfortunately, there is a lack of good-quality research on this issue. So, it is unclear whether protein powder specifically impacts stone formation.

That said, some studies have found that exceeding recommended protein intake can adversely affect the kidneys. In addition to impacting kidney function, excess protein may also harm the liver, increase cancer risk, lead to bone disorders, and cause a calcium imbalance. These issues may be an even greater concern for someone with existing kidney issues. 

Know Your Recommended Protein Intake

For this reason, it is important to be aware of how much protein you need based on your body weight. This helps ensure that you get enough of this macronutrient. It also prevents you from getting so much that it stresses the kidneys unnecessarily.

The Mayo Clinic recommends that people following a 2,000-calorie diet consume 50 to 175 grams of protein per day. This is based on 0.8 grams of protein per kilogram of body weight. 

For people who are more physically active, higher protein amounts are generally needed. Active individuals should get between 1.1 and 1.5 grams of protein per kilogram of body weight. Those who lift weights would benefit from 1.2 to 1.7 grams per kilogram of body weight daily.

Animal Protein vs. Plant Protein: Does It Matter for Kidney Health?

One review of research studies indicates that protein type may make a difference when it comes to kidney health. This review found that plant protein sources were associated with lower CRP levels. CRP stands for c-reactive protein and is a sign of inflammation. Conversely, consuming more animal protein was linked to increased CRP levels.

Hemp protein is an example of a plant protein. Whey protein is an animal protein as it comes from cows. Does this mean that whey protein is bad? Not necessarily. However, if you have reduced kidney function, you may be better off with a different type of protein powder. 

If You Have Kidney Disease (or Kidney Damage)

If a client has kidney disease or their kidney is otherwise compromised, their healthcare provider can help decide if a protein powder is safe. The provider can also offer other recommendations to better support kidney health.

For instance, they may suggest that the person follow a kidney-friendly diet. This involves limiting sodium intake and avoiding high protein diet plans. Together, this reduces stress on the kidneys.

Ways to Prevent Kidney Stone Formation

Finding ways to stop a kidney stone before it can start can save clients a lot of pain and discomfort. Harvard Medical School shares that kidney stone prevention involves:

• Staying hydrated. This helps the kidney by giving it more fluid to dissolve the waste that can lead to a stone. Making some of these beverages citrus-based may further help keep stones from forming.

• Increasing calcium intake. Calcium reduces stone formation by binding to oxalate. This reduces oxalate concentration in the urine, lowering the risk that the oxalate will bind to calcium and lead to a stone.

• Eating low sodium. The more sodium you consume, the higher the calcium in your urine. So, one way to prevent a calcium stone is to watch your sodium intake. Taking this action is also good for your heart.

• Avoiding foods high in oxalate. If you are prone to oxalate stones, reduce or eliminate foods that contain a lot of oxalates. This includes chocolate, tea, nuts, beets, and spinach.

If a Kidney Stone Develops

If you or a client suspect that a kidney stone has developed, seeking medical attention can help resolve the stone before it gets bigger. The healthcare provider can do blood and urine tests to confirm whether a stone exists. A CT scan may also be conducted.

Treatment of kidney stones depends on stone size. If the stone is small, increasing water intake, taking over-the-counter pain relievers, and using medication to help pass the stone may be recommended. Larger stones may require medical intervention. This can include using sound waves to break up the stone, having surgery to remove it, or removing the stone with the help of a scope.

What You Can Do as a Personal Trainer

Advising clients about how to resolve kidney stones is outside of a personal trainer’s scope of practice. What you can do, however, is help your clients understand the importance of not exceeding their recommended protein intake. 

If you want to take this one step further, you can become a certified nutritionist and develop a meal plan that contains the right amount of protein based on the client’s needs. ISSA offers a Nutritionist certification that teaches you how to create customized diet plans that provide adequate (not excessive) amounts of both the macro and micronutrients the client’s body needs for optimal function. 

References

Ko, G. J., Rhee, C. M., Kalantar-Zadeh, K., & Joshi, S. (2020). The Effects of High-Protein Diets on Kidney Health and Longevity. Journal of the American Society of Nephrology: JASN, 31(8), 1667–1679. https://doi.org/10.1681/ASN.2020010028

Ko, G. J., Rhee, C. M., Kalantar-Zadeh, K., & Joshi, S. (2020). The Effects of High-Protein Diets on Kidney Health and Longevity. Journal of the American Society of Nephrology: JASN, 31(8), 1667–1679. https://doi.org/10.1681/ASN.2020010028

Kidney Stones. National Kidney Foundation. (2022). Retrieved 3 June 2022, from https://www.kidney.org/atoz/content/kidneystones.

Delimaris I. (2013). Adverse Effects Associated with Protein Intake above the Recommended Dietary Allowance for Adults. ISRN nutrition, 2013, 126929. https://doi.org/10.5402/2013/126929

Are you getting too much protein?. Mayo Clinic Health System. (2022). Retrieved 3 June 2022, from https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/are-you-getting-too-much-protein.

Aycart, D., Acevedo, S., Eguiguren-Jimenez, L., & Andrade, J. (2021). Influence of Plant and Animal Proteins on Inflammation Markers among Adults with Chronic Kidney Disease: A Systematic Review and Meta-Analysis. Nutrients, 13(5), 1660. https://doi.org/10.3390/nu13051660

5 steps for preventing kidney stones - Harvard Health. Harvard Health. (2020). Retrieved 3 June 2022, from https://www.health.harvard.edu/blog/5-steps-for-preventing-kidney-stones-201310046721.