A low protein diet is needed to manage chronic kidney disease, but what if you take too little protein?
Most people are probably aware that we all have two kidneys that filter out waste products from our body in the form of urine.
But many might not be aware that these bean-shaped, fist-sized organs can actually take a great deal of punishment before showing any noticeable symptoms.
In fact, we can live a fairly normal life with just one kidney, as both kidney transplant recipients and donors can attest to.
The downside however, is that we are often unaware that anything is wrong with our kidneys until it is too late.
According to consultant nephrologist Dr Chong Yip Boon, around 30-40% of chronic kidney disease (CKD) patients who come to see him for the first time already have such advanced conditions that most of their kidney function cannot be salvaged.
“Most patients with CKD do not have symptoms, or only mild to moderate symptoms; that is why it is called ‘a silent killer’,” he says.
Many of the symptoms are also fairly generic, like loss of appetite and weight, nausea and vomiting, itchiness, fatigue, swollen legs and frothy urine, making it a tough job to correctly diagnose CKD.
And even these symptoms only tend to manifest in the later stages of the disease, often when patients are just a step away from needing dialysis.
By then, it is a fighting action to maintain the remaining kidney function, rather than curative, which can be undertaken at the earlier stages.
Causes and management
According to Dr Chong, the causes of CKD include diabetes, hypertension, glomerulonephritis (i.e. inflammation of the glomerulus), kidney stones, autoimmune diseases like systemic lupus erythematosus (SLE), genetic conditions like polycystic kidneys, recurrent kidney infections and certain drugs like traditional medicine and painkillers.
He notes: “The most common cause of chronic kidney disease is diabetes. It accounts for about 20-30% of cases in the United States and Europe, but in Malaysia, it is around 50%.”
He adds that this is why type 2 diabetic patients in Malaysia need to be screened for kidney disease, as well as check their eyes, within the first year of their diagnosis.
“Management is usually based on the underlying cause. The most important part of management is controlling the risk factors,” he says.
This, for example, means that in diabetes, the blood sugar must be controlled to within a very narrow margin.
High blood pressure and high cholesterol levels must also be controlled.
Protein in urine is reduced by taking drugs like angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs).
A healthy, low salt, low protein diet needs to be adopted.
“And avoid medications like traditional medicine, especially in capsule form as they can contain heavy metals, and NSAIDs (non-steroidal anti-inflammatory drugs), which can worsen the kidneys,” says Dr Chong.
Cutting down on protein
While some might assume that the dietary advice is generic, recommended as part of practising a healthier lifestyle or as management measures for conditions like diabetes and hypertension, there are actually specific reasons for a change in diet for CKD patients.
Among its other duties, the kidney is responsible for the excretion of urea from the body.
Urea is a byproduct of the metabolic processes that convert excessive amino acids – the basic building blocks of proteins – in our body into other useful biological molecules.
It is also the main form in which nitrogen waste products are removed from the body,
Therefore, the more protein we eat, the more urea is produced, and the harder our kidneys need to work to get rid of it.
With healthy kidneys, this extra workload is no problem at all.
However, if the kidneys are damaged, then any extra work will only speed up its deterioration.
Dr Chong notes that the recommended daily protein intake for healthy adults is 0.8g per kilogramme of body weight. “But Malaysians usually take more than 1g per kilogramme – we have a high protein diet.”
He says that CKD patients need to lower their protein intake to 0.6g per kilogramme a day, or even 0.3-0.4g if aggressive management is required. “You really have to cut down a lot.”
Excessive urea in the body also causes many of the symptoms of CKD, including loss of appetite and weight, nausea and vomiting, itchiness and fatigue.
So, decreasing the urea load by consuming less protein would also help patients control their symptoms.
The kidney also helps control the levels of phosphate in the body through excretion.
In CKD, phosphates cannot be excreted efficiently, resulting in high phosphate blood levels (hyperphosphataemia).
Says Trento, Italy, Provincial Health Services Chief of Nephrology and Dialysis Prof Dr Giuliano Brunori: “In patients with chronic kidney disease, the first cause of death is cardiovascular disease – it accounts for about 50% of deaths.
“One of the reasons is related to hypertension and vascular calcification related to hyperphosphataemia.
“This is the reason we use low-protein diets in chronic kidney disease as the phosphate load is lower than in a normal diet.
“So you can decrease the level of phosphate in the blood and reduce the risk of blood vessel calcification.”
Proteins are rich in phosphorus and provide a large portion of dietary phosphorus.
Alternative protein source
However, a low-protein diet is not without its dangers.
According to Prof Brunori, at least one-third of CKD patients suffer from malnutrition.
He adds: “Malnutrition is related to infection. So, patients with malnutrition present with very high rates of infection, and infections are very dangerous in patients with chronic kidney disease.”
Due to the disease’s symptoms of loss of appetite, nausea and vomiting, many CKD patients also tend to eat even less than they should.
This further exacerbates their nutritional status when they are already restricting their calorie and protein intake.
One way to help solve this problem is through keto acid supplementation.
Keto acid supplementation
Keto acids are the equivalents of essential amino acids, but without the nitrogen.
They come in pill form, allowing patients to easily consume them. And the lack of nitrogen means that patients can get their supply of amino acids without burdening the kidney with extra urea excretion.
In fact, Dr Chong shares that the keto acids will pick up nitrogen in the body to complete their transformation into amino acids, thus, further decreasing the kidneys’ workload.
Studies have shown that the combination of a low protein diet and keto acid supplementation can preserve kidney function sufficiently enough to delay the need for dialysis.
Considering the high cost of dialysis and the decrease in quality of life of patients on dialysis, this is an important factor for both patients and their caregivers, as well as healthcare agencies.
Prof Brunori shares that in a small randomised controlled trial he and his colleagues conducted in 2007, it was observed that end-stage renal disease patients were able to delay dialysis for up to a year when they followed a low protein diet and took keto acid supplements.
“You have to start dialysis when the kidney is working at less than 5%. We started (a low protein diet and keto acid supplements), in our study in Italy, when the kidney was working at 5%, and we were able to postpone dialysis for a year.
“But if you start when the kidney is working at 20-25%, then you can gain more years,” he says.
The trial involved 112 elderly patients whose kidneys were only working at about 5-7% of normal.
Prof Brunori is currently conducting a study to see how long CKD patients with 20-25% kidney function can delay dialysis with a low protein diet and keto acid supplements.
Dr Chong notes that the diet and supplements are even prescribed for some dialysis patients to help maintain their nutritional status.
He also cautions patients not to think that the keto acid pills can work by themselves.
“It is a supplement. There is no point taking it without the low protein diet,” he says.
“Patients need to see the dietitian first and see if they are willing to adopt the low protein diet.”
However, for those who do strictly follow the diet and keto acid supplementation, the benefits can be felt outwardly, as well as inwardly.
One of Dr Chong’s patients, 55-year-old May Cheng, who has been on the low protein diet and keto acids for the past eight years, shares: “My appetite has started to improve, I sleep well and have regained a normal life. At the same time, my serum creatinine have been maintained at satisfactory levels.”
This article is courtesy of Fresenius Kabi.