Protein supplements — trendier than ever, but take note of their impact to your kidney health

Taking a walk down the health aisle at a grocery store or pharmacy, you will likely see shelves full of protein-packed snacks, meal replacements or supplements. Scroll through social media, and you may see multiple ads for protein-based shakes, bars or powders that say they can help you bulk up, regain muscle mass as you age or even help you lose weight.

So, how much protein do you actually need for a healthy lifestyle? Should you be stocking up and focusing on a protein-rich diet? And does that change if you are living with kidney disease?

Our Q&A with Kathy Wong, a registered dietitian nutritionist and a member of the American Kidney Fund (AKF)'s Dietitian Advisory Group for Kidney Kitchen®, sheds some light. 

Let's start with the basics: can you please describe what protein is and why it is important for our bodies?

Protein is an essential macronutrient made up of amino acids, which are the building blocks of tissues in the body. Protein is critical for growth, tissue repair, enzyme and hormone production, and immune function.

Although protein is essential for maintaining overall health, your exact protein needs may vary if you have chronic kidney disease (CKD). Eating too little protein may lead to malnutrition, while having too much protein can lead to kidney damage. 

Can you tell us about different protein sources? Which foods are considered high in protein? Low in protein?

Protein can come from both animal and plant-based foods, each playing a valuable role in a balanced diet. 

Animal-based foods include: 

• meat (such as pork, beef and lamb)
• poultry (like chicken and turkey)
• fish and seafood (including salmon, tuna and shrimp)
• eggs and dairy products (such as milk, cheese and yogurt) 

These are also valuable sources of nutrients like iron, vitamin B12 and zinc. However, some animal-based proteins, particularly fatty cuts of meat, can be higher in saturated fat and cholesterol, which may negatively impact heart health. It's also beneficial to limit processed meats and processed foods in general, as they often contain added sodium and phosphorus, which is an especially important consideration if you have kidney disease.

Plant-based proteins are found in a variety of foods, including 

• legumes (such as lentils, chickpeas and black beans)
• soy products (like tofu, tempeh and edamame)
• whole grains (such as quinoa, brown rice and oats)
• nuts and seeds (including almonds, peanuts and chia seeds) 

Plant-based proteins are generally low in saturated fat and cholesterol, and the phosphorus in plants is not absorbed as much by the body which is an advantage for kidney health. Low-protein foods contribute minimal protein and are not considered significant sources. These are often emphasized in low-protein diets for non-dialysis CKD patients to help slow disease progression.

Now we know this will vary from person to person, but in general, what is the amount of protein that is recommended for a healthy adult? 

For generally healthy adults 18 years and older, the Recommended Dietary Allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day (g/kg/day). This means that if you weigh 180 pounds (about 81.5 kilograms), then it is recommended you have about 65 grams of protein each day. This represents the minimum intake needed to meet the nutritional requirements of most healthy individuals but does not include factors like physical activity and health issues. Protein needs may be higher for certain populations — such as older adults, athletes or people with specific health conditions — to support the maintenance of muscle mass, strength and overall physical function.

We know that protein intake is important to manage if you have kidney disease, and that also depends on what stage of kidney disease you're in. In general, why is this the case – what is the connection between protein and the kidneys?

Protein is essential for overall health but is especially important if you have kidney disease due to how the body metabolizes (breaks down and uses) protein and then removes waste. Inadequate protein can lead to malnutrition, while excessive intake may make your kidney function decline faster or contribute to uremic symptoms — when too much waste product builds up in your blood — particularly in people who are not yet on dialysis.

For those with CKD, the kidneys cannot efficiently remove these waste products from the blood. As a result, excess protein intake can lead to a buildup of waste, potentially causing symptoms such as nausea, fatigue and confusion. Furthermore, in the earlier stages of CKD, a high-protein diet can place an increased workload on the kidneys, which may contribute to a faster decline in kidney function if not carefully managed.

That's why having balanced protein — not too much, not too little — is so important in CKD management.

Does having kidney disease change the amount of protein you should have in a day?

Yes, CKD does change protein needs, particularly in the CKD stages 3–5 (not on dialysis). In these stages, reducing protein is often recommended to help slow disease progression and limit the buildup of waste products.

Once a person begins dialysis, however, protein needs increase due to losses that occur during the treatment process, along with the need to support muscle maintenance and overall health.

The exact amount of protein needed varies from person to person and should be based on disease stage, nutritional status and ongoing clinical monitoring. For this reason, it's important to work with a registered dietitian nutritionist (RDN) experienced in kidney care, who can help ensure you're getting enough protein to preserve muscle mass while still protecting your kidneys.

In CKD, the type of protein is just as important as the amount. It's generally recommended to focus on high-quality, nutrient-dense protein sources (meaning foods that are rich in protein and also provide valuable nutrients) while limiting those high in saturated fat, sodium and phosphorus additives.

More and more we hear a lot about high-protein diets, whether it's related to an increase in protein supplement intake, especially among young boys and men who may be aiming to bulk up, or women incorporating more protein for healthy aging and weight loss. Are there precautions that should be taken by those who incorporate protein supplements such as shakes and protein bars into their diets to ensure they are staying within a healthy protein range?

Yes, protein supplements can be appropriate when used to meet a specific nutritional need or to address a deficiency. This applies to healthy people (such as athletes, older adults or those recovering from illness or surgery) as well as to individuals with CKD who may have increased protein requirements, particularly those on dialysis.

For healthy adults without kidney disease, the body can typically digest, absorb and use protein you get from regular food consumption to support muscle maintenance, immune function and overall health. However, excess protein beyond the body's needs is metabolized, and the waste products must be removed by the kidneys.

Consuming more protein than necessary doesn't generally offer additional health or performance benefits. Instead, it may lead to: 

• increased fluid needs due to higher urea (a waste product) production
• potential dehydration if fluid intake doesn't increase accordingly
• unnecessary expense — especially when using supplements without a clear benefit

One important consideration is that chronic kidney disease is often undiagnosed, particularly in its early stages. For individuals with reduced kidney function, high protein intake can: 

• increase the workload on the kidneys, causing a strain on the kidneys
• speed up the CKD progression
• worsen uremic symptoms (like nausea, fatigue and mental confusion) in later stages of CKD

Patients with CKD prior to needing dialysis often benefit from a moderate or reduced protein intake to help preserve kidney function and limit the buildup of waste. Supplementing the diet with additional protein without knowing your true needs can therefore be harmful, especially for those with undiagnosed or early-stage CKD.

What are signs that you are having too much protein? Too little?

It's important to note that not everyone will experience obvious symptoms from consuming too much or too little protein. In generally healthy adults, the body can typically tolerate a moderate increase in protein intake, especially when overall nutrient balance and hydration are maintained. However, long-term excessive protein intake — particularly when not medically indicated — can lead to potential side effects, including: 

• Dehydration – Higher protein intake increases urea production, which may raise fluid needs.
• Digestive issues – Constipation or diarrhea can occur, particularly if the diet is low in fiber.
• Bad breath – Often linked to ketosis (when your body burns fat for energy instead of using sugar) from low-carbohydrate, high-protein diets.
• Unintended weight gain – Protein provides calories; excess intake can be stored as fat.
• Kidney strain – For those with CKD or undiagnosed kidney impairment, high protein intake can contribute to nitrogenous waste buildup and worsen uremic symptoms such as nausea, fatigue and mental confusion.

On the other hand, too little protein intake, especially over time, can lead to protein deficiency or protein-energy wasting (PEW), a concern in older adults, those with chronic illnesses and people with CKD, particularly in advanced stages. Some possible signs include:

• Muscle loss or weakness
• Fatigue or low energy
• Slow wound healing
• Brittle hair and nails
• Frequent illness (due to weakened immune function)
• Edema (swelling) - low protein levels can affect fluid balance, especially in severe deficiency
• Unintended weight loss - especially loss of lean body mass (muscle mass)

How can someone make sure they are getting the right amount of protein?

The best way to ensure you're getting the right amount of protein is by understanding your individual protein needs. Your needs should be individualized to help support overall health, prevent malnutrition and — especially in CKD — avoid overloading the kidneys with excess protein waste. This is why working with a registered dietitian nutritionist (RDN) is the most effective way to assess your needs. An RDN can calculate your protein requirements and guide you through what food (and supplements if needed) are best for you while taking into account your medical history and dietary preferences.

What are ways to keep track of the amount of protein you are eating?

You can track protein by:

• Using an app like MyFitnessPal, Calorie Counter and Loose It!
• Keeping a food journal
• Learning portion size visuals
• Reading nutrition labels
• Getting personalized guidance from an RDN

Each method has its strengths. The key is to choose a method that works for you. Combining a few of these may help you stay consistent and meet your individual goals.

What advice would you offer to those who are using protein supplements regularly?

If your protein supplement was recommended or prescribed by your doctor or dietitian, that's great! Be sure to continue communicating with them regularly so they can adjust recommendations based on your changing health needs.

If you use supplements, always tell your doctor or dietitian what kind, how much, and how often you take it. Some supplements may contain added phosphorus, potassium or sodium which can be harmful to your kidneys. 

What is the most important takeaway for people living with kidney disease about using protein supplements?

Protein supplements can be useful for some people, but unnecessary or potentially harmful for others. Whether you're healthy, active or managing a condition like CKD, it's important to work with a doctor or a dietitian to determine your individual protein needs. A registered dietitian can help you navigate your protein goals safely.

To learn more about protein and kidney disease, visit AKF's Kidney Kitchen protein website. You can also find kidney-friendly recipes to fit your protein needs and protein food guides to help you understand how much protein is in different foods. 

Kathy Wong, RDN has been a registered dietitian since 2014. For the past seven years, she has been a renal dietitian with DaVita Kidney Care, providing nutrition support to in-center dialysis patients. She currently serves as a member for the American Kidney Fund (AKF) Dietitian Advisory Group. She is also an actively participating member of the Academy of Nutrition and Dietetics Renal Practice Group.

References:

1. Academy of Nutrition and Dietetics (AND)
   • Academy of Nutrition and Dietetics. Nutrition Care Manual – Protein. https://www.nutritioncaremanual.org(Access may require subscription)
   • Academy of Nutrition and Dietetics. Position Paper: Health Implications of Dietary Protein. J Acad Nutr Diet. 2016;116(11):1781–1791. https://doi.org/10.1016/j.jand.2016.06.375
2. Kidney Disease Outcomes Quality Initiative (KDOQI)
   • KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update. Kidney Medicine. 2020;2(5):427–458. https://doi.org/10.1016/j.xkme.2020.04.006
3. USDA FoodData Central (for standardized nutrient values)
   • U.S. Department of Agriculture, Agricultural Research Service. FoodData Central. https://fdc.nal.usda.gov
     (Used for nutrient content like protein per standard portion size of common foods.)
4. National Kidney Foundation (NKF)
   • National Kidney Foundation. Eating Right for Chronic Kidney Disease. https://www.kidney.org/nutrition