Keto Diet: Friend Or Foe For Kidney Disease Patients?

The ketogenic diet, or keto diet, is a low-carb, high-fat diet that has been used to help people lose weight. It was originally developed in the 1920s as a treatment for epilepsy. The diet involves a person entering a state of ketosis, where the body uses fat instead of carbohydrates for energy. While the keto diet has been shown to be effective for weight loss, there are concerns about its impact on kidney health, especially for those with kidney disease. Some sources suggest that the keto diet may contribute to an increased decline in kidney function for those with kidney disease, while others argue that it can be safe and effective for weight loss in patients with mild kidney failure when conducted under medical supervision.

The keto diet and kidney stones

The keto diet is a low-carb, high-fat diet that can lead to a metabolic state called ketosis, where the body uses fat and ketones as its primary energy source instead of carbohydrates. While the keto diet is often praised for its weight loss benefits, it also carries certain risks, including kidney stones.

Kidney stones are a significant complication of the keto diet, with a prevalence of 3-10% in people on the diet, compared to 1 in several thousand in the general population. The keto diet can cause several changes in the body that contribute to the formation of kidney stones, including:

• Increased acidity in the blood and urine: A high intake of animal foods, which are staples of the keto diet, can lead to increased acidity in the blood and urine. This can lead to the excretion of more calcium in the urine, which can form kidney stones.
• Reduced citrate levels in the urine: Citrate binds to calcium and prevents the formation of kidney stones. The keto diet has been linked to reduced levels of citrate in the urine, which can increase the risk of kidney stone formation.
• Dehydration: The keto diet can interfere with the normal thirst mechanism, leading to dehydration. Dehydration is a significant factor in the formation of kidney stones.

The risk of kidney stone formation is particularly high in children on the keto diet. In a study of 36 studies with 2795 patients on keto diets, the estimated pooled incidence of kidney stones was 5.9%, with a mean follow-up time of 3.7 years. The incidence was similar in children (5.8%) and adults (7.9%).

Uric acid stones are the most common type of kidney stones in people on the keto diet, followed by calcium-based stones. To prevent kidney stones, it is recommended to liberalize fluid intake and use oral potassium citrate to alkalinize the urine. Regular monitoring of urine calcium-to-creatinine ratio and ultrasonography is also recommended to detect kidney stones early.

The keto diet and creatinine levels

Creatinine is a waste product generated when you use your muscles. It is transported to the kidneys, which filter it through your urine. However, if your kidneys aren't working properly, creatinine levels in your blood can build up.

The keto diet is characterised by very low-carbohydrate, modest protein meals that focus heavily on fat intake. The keto diet has been linked to an increased decline in kidney function for those with kidney disease. This is because eating more protein and animal fats generates more acid in the blood, increasing the risk of kidney stones and chronic kidney disease.

However, there is limited evidence to suggest that the keto diet has a negative impact on kidney function in healthy individuals. A 2016 meta-analysis of nine randomised controlled trials found a greater improvement in kidney function in those who ate a low-carbohydrate diet compared to those who consumed a control diet. A more recent meta-analysis of 12 randomised controlled trials found no evidence that low-carbohydrate diets are harmful to kidney health, even in people with type 2 diabetes.

Creatinine levels and kidney disease

High creatinine levels can be a sign of kidney disease. Other signs include changes in urination, puffiness around the eyes, and swelling in the feet or ankles.

Lowering creatinine levels

There are several ways to lower creatinine levels and support kidney health:

• Avoid supplements containing creatine
• Reduce protein intake
• Talk to your healthcare professional about fluid intake
• Lower salt intake
• Avoid overusing NSAIDs
• Quit smoking
• Limit alcohol intake

The keto diet and stage 3 kidney disease

The ketogenic (keto) diet is a high-fat, low-carbohydrate, and moderate-protein diet that puts your body in a state of ketosis, which causes weight loss. While the keto diet can help with weight loss and better control your diabetes in the short term, its long-term effects are unknown. The keto diet is also quite restrictive, which can make it difficult to follow long-term.

Kidney Disease and the Keto Diet

Chronic Kidney Disease (CKD) is a generic diagnosis given to people with some form of kidney damage. CKD is divided into five stages, depending on how well the kidneys are filtering. Obesity, diabetes, and high blood pressure are risk factors for the development of kidney disease, and these can be managed by diet.

The keto diet shares some similarities with a kidney-healthy diet, such as avoiding ultra-processed, high-carb foods, sugary drinks, and limiting portion sizes. However, there are also differences and potential dangers to consider.

Protein Intake

The keto diet typically includes between 1.2 and 1.7 grams of protein per kg of body weight per day, with no distinction between animal and plant-based proteins. While this amount may be safe for those with normal kidney function, people with kidney disease benefit from a lower protein intake of between 0.6 and 0.8 grams per kg of body weight. Excess dietary protein can put extra stress on the kidneys, causing the tiny filters in the kidneys to become scarred and leading to a decline in kidney function over time.

Carbohydrates, Sodium, and Plant-Based Proteins

In a kidney-healthy diet, carbohydrates are often used to provide calories without adding extra protein. In contrast, the keto diet strictly limits carbohydrates. Additionally, a lower sodium diet is often beneficial for people with CKD, while the keto diet often recommends extra sodium, especially when starting out. Recent research also suggests that plant-based proteins may be better for people with kidney disease than animal protein, but the keto diet does not make this distinction.

Kidney Stones

The keto diet has been linked to an increased risk of kidney stones, especially in children with epilepsy, as the diet was initially designed to manage seizures in this population. High animal protein and sodium intake, which are common in the keto diet, are risk factors for certain types of kidney stones.

While the keto diet may be effective for weight loss, there are potential risks and unknown long-term effects, especially for people with stage 3-5 CKD. The keto diet's high protein intake and potential impact on metabolic acidosis can strain already troubled kidneys. Therefore, it is important to consult with a healthcare professional before starting any new diet, especially if you have kidney disease.

The keto diet and stage 4 kidney disease

The keto diet is a high-fat, adequate-protein, and low-carbohydrate nutrition plan that forces the body to burn fats and use ketone bodies as an alternative metabolic fuel. The diet is characterised by very low-carbohydrate, modest protein meals that focus heavily on fat intake. The aim is to induce "ketosis", which generates ketone bodies that serve as an energy source.

The keto diet has been used to help with weight loss, diabetes management, and liver disease. However, it may also contribute to an increased decline in kidney function for those with kidney disease. This is because eating more protein and animal fats generates more acid in the blood, which can lead to kidney stones and chronic kidney disease.

For those with stage 4 kidney disease, also known as severe chronic kidney disease, the keto diet may pose additional risks. Stage 4 kidney disease is characterised by a severe decrease in kidney function, with a glomerular filtration rate (eGFR) of 15-29 mL/min/1.73m2. At this stage, the kidneys are no longer able to adequately filter waste and fluid from the blood, and the body may retain excess fluid, leading to swelling in the legs, ankles, and face.

The high protein intake associated with the keto diet may further increase the risk of kidney damage in individuals with stage 4 kidney disease. High protein intake has been shown to cause an increase in kidney volume and weight, leading to expansion of the mesangial matrix and tubulointerstitial fibrosis. This can lead to a further decrease in kidney function and may accelerate the progression of kidney disease.

Additionally, the keto diet may worsen metabolic acidosis, a common complication of chronic kidney disease, which can affect bone and muscle health. Those with stage 4 kidney disease may also need to pay close attention to their intake of potassium and phosphorus, as their kidneys may not be able to handle the load, leading to complications.

While the keto diet may be effective for weight loss in some individuals, it may not be suitable for those with stage 4 kidney disease due to the potential risks to kidney function and overall health. It is important for individuals with stage 4 kidney disease to consult with their healthcare provider before starting any new diet, including the keto diet, to ensure that it is safe and appropriate for their individual needs.

Alternative Dietary Options

For those with stage 4 kidney disease, it is important to adopt a healthy lifestyle with balanced and portioned meals. This includes adequate amounts of protein, carbohydrates, fat, fibre, and other micronutrients. Restricting salt intake and ensuring proper hydration can also help to alleviate stress on the kidneys.

It is recommended that individuals with stage 4 kidney disease consult with a nephrologist or a registered dietitian to determine the best dietary approach for their specific needs. There are alternative diets that may be more suitable and help with weight loss while also supporting kidney health.

Nutritional deficiencies

The keto diet is also associated with a decrease in fat-soluble vitamins A and E, as well as magnesium and calcium. This is because the diet focuses on high-fat foods and severely restricts the intake of fruits, vegetables, legumes, and dairy—food groups that are rich in these nutrients.

The keto diet's restriction of fruits, vegetables, legumes, and dairy also increases the risk of nutritional deficiencies in B vitamins (often found in fortified whole grains and produce), calcium (found in dairy and dark greens), vitamin D, and electrolytes like potassium.

To prevent these deficiencies, it is important to work with a dietitian to assess the appropriate supplement plan.

Frequently asked questions