Protein intake in People with CKD

How does Chronic Kidney Disease Affect Protein Intake for Physical Performance?

In healthy individuals, protein is an essential macronutrient that is vital in supporting cellular function as well as promoting increase in muscle mass, strength, and recovery. In fact, for active and athletic individuals, it is recommended to consume high quality protein of 1.2-2.0 g/kg of bodyweight per day. However, in individuals with kidney failure – specifically chronic kidney disease, how does their condition impact protein intake for physical performance? To have a better understanding, let’s first discuss the physiological impacts of chronic kidney disease (CKD).

What is Chronic Kidney Disease (CKD)

CKD is a long-term condition characterized as a progressive loss of kidney function, in Canada there are approximately 4 million people with CKD.

There are 5 stages of CKD where the last stage – stage 5 is when the individual has less than 15% of kidney function left and require dialysis to replace impaired kidney function. But if you are fortunate to have access to a kidney transplant, that is also an option.

Symptoms of CKD include fatigue, poor appetite, trouble sleeping, swollen feet and ankles (from fluid retention due little urine output).

CKD Stage

Chart adapted from: National Kidney Foundation

*This is the stage where individuals will prepare for dialysis or kidney transplant

 With impaired kidney function, the kidneys cannot efficiently remove excess metabolic waste, electrolytes, and water from the bloodstream – the kidneys produce very little to no urine output. As a result, there is accumulation of toxins and water in the blood and tissues.

 With this in mind, if an athletic individual was recently diagnosed with stage 3 CKD (with a 30 to 59% kidney function) is it still possible to maintain the same dietary intake, specifically a high protein intake of 1.2-2.0g/kg? In short, the answer is NO. This is because, physiologically there are concerns around high protein intake in people with impaired kidney function. The idea is that consuming high amounts of protein increases protein catabolism where the by-products of protein breakdown, urea and nitrogenous waste compounds, accumulate in the blood. Since the impaired kidneys excrete very little to no urine, the protein waste products remaining in the blood are toxic for the body, progressively impairing kidney function and other organs such as the brain and heart. Therefore, as a means to preserve kidney function, it is recommended to follow a protein restricted diet in the early stages of CKD to help delay kidney function decline.

 Can Low Protein Intake Cause Muscle Wasting in People with CKD?

Table 2: Current recommendations for protein intake in people with CKD; protein intake declines as CKD advances as a strategy to reduce accumulation of urea and nitrogen waste products in the blood which further damages the kidney. In contrast, stage 5 of CKD is associated with increase in protein need, due to dialysis treatment causing excess loss of protein. For more information, see: KDOQI

 There are concerns around long term low-protein intake in people with CKD, as protein restriction can potentially lead to muscle wasting (atrophy) and malnutrition. However, if energy intake is adequate and there is sufficient intake of essential amino acids, then potential complications associated with low-protein intake can be prevented. Ensuring adequate energy intake combined with low protein can help to reduce protein catabolism. I suppose you are thinking: wouldn’t a low protein intake impair protein synthesis and muscle development?

 A study investigating the effects of resistance training and low protein diet (0.6g/kg) in people with CKD - showed an increase in size of type I and type II muscle fibres and increase in muscle strength compared to the group that did not undergo resistance training. It is important to note that sufficient energy supply needs to be available to fuel the activity (i.e. carbohydrates and fats) to prevent catabolism of protein for potential energy use. As long as energy intake matches energy expenditure, a low-protein diet can still produce positive outcomes in people with CKD while minimizing the risk of exacerbating the rate of kidney damage.

 In people who approach stage 5 of CKD, their protein needs increase significantly due to protein loss from dialysis treatments. What is also interesting is that many studies show that for CKD patients on dialysis, their resting energy expenditure increases – this is something to be mindful of where both protein needs and energy needs increase once someone approaches stage 5 of CKD.

Final Thoughts:

Overall, when considering nutritional needs in active CKD individuals, there are many complex and interacting factors to consider including the stage of CKD, lab values, level of physical activity and medications. The most important point is that for people with CKD, protecting and preserving kidney function takes precedence over exercise performance and muscle strength development. The goal is to provide a practical approach in maintaining an active lifestyle and quality of life as the individual continues to live with an irreversible condition.

 Disclaimer: It is important that you speak with your nephrologist or family physician to share that you are training or exercising so that they can closely monitor your health status and assess if you are medically safe to engage in specific types of training/exercise regimen. On the same note, you would attain tremendous benefit from a dietitian or a nutrition practitioner – someone who is familiar with chronic kidney disease that can provide guidance on how to help you fuel your activity.