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Kidney Disease and Generalized Nutrition

Nina Ghamrawi, MS, RD, CDE
3
November 16, 2021

Currently, only 10% of patients with kidney disease see a Dietitian before reaching ‘end-stage’ kidney failure and requiring dialysis. Around 90% of adults don’t know they have declining function - including half of those patients that have already had a significant loss in kidney function. Depending on underlying factors that may worsen your CKD risks, making dietary changes that align with the root causes will play an important role in slowing or stopping kidney disease from getting worse. Here we will talk about generalized nutrition pointers to help protect the kidneys.

Several different diet types have potential to help protect the kidneys from decline. Among these are the DASH diet, Mediterranean-style diets, and vegetarian/vegan, or plant-based diets. There’s no conclusive evidence that one diet is better than another, but all these diet patterns seem to emphasize the same things: importance of fruits, vegetables, whole grains, natural foods with low processing, and low sodium content.

(See other research articles here regarding CKD and diet: general diet and CKD, mediterranean diets and CKD, plant based diets and CKD)

Many patients with advanced stages of kidney disease need to limit potassium, phosphorous, sodium, protein, and also may need to restrict fluids. However take extreme caution with this diet, and only restrict foods as prescribed by your physician, and under the guidance of a Dietitian.

Protein

Traditionally, a main pillar of the diet for kidney disease has been a restriction in protein, supported by numerous trials. Protein digestion in the body results in more filtering work for the kidneys, making them overwork temporarily to digest a higher protein meal, and potentially affecting long-term kidney function.

Some research (MDRD trial) failed to show a strong link between protein restriction and kidney function, however, when analyzing the data from that research from a different angle, it appears that protein restrictions still remain a cornerstone of diets for kidney disease.

The current recommendations from the National Kidney Foundation recommend that patients with stage 3 to stage 5 kidney disease restrict dietary protein to around 0.6g/kg of your body weight per day (Around 46g per day for someone that weighs 170 lbs). People on dialysis or with diabetes may benefit from even less protein.

Although most research studies and recommendations have been focused on the amount of protein consumed per day, it is also important to note the newer research that is encouraging a change in protein quality, as well. Many Dietitians encourage patients with CKD to consume more plant proteins instead of animal proteins for a few main reasons:

  1. Diets higher in plant protein have been shown to cause less stress during kidney filtering than plant-based protein
  2. Plant-based proteins tend to help lower blood pressure better than a diet rich in animal-based proteins
  3. Diets containing more plant-based foods are linked to lower risk of death in CKD patients

Sodium

It is widely known that restricting sodium is critical for kidney function. This is mainly due to the strong link between sodium and high blood pressure. High blood pressure is both a cause of, and caused by kidney disease. Because high blood pressure may slow blood flow through the kidneys when there’s a backup of high blood pressure elsewhere, but when the kidneys are having trouble filtering, this may lead to a backup of blood before the kidneys, causing high blood pressure. The guidelines from the National Kidney Foundation recommend keeping sodium intake to under 2300 mg per day. Depending on your individual health needs, blood pressure, and blood tests, you may need more restriction.

Potassium and Phosphorous

The need to restrict potassium and phosphorous depends on your blood test results. While protein and sodium are important even in early stages of CKD, phosphorous and potassium intake often become more of an issue in later stages. If the kidneys lose their ability to clear these minerals, these can build up in the blood, leading to muscle weakness, hypertension, bone disorders, and problems with processing of other minerals. Always consult with a dietitian and your doctor before restricting foods, since over-restricting may mean that you lose out on plenty of beneficial plant foods that also boost alkalinity.

Diets that are more alkaline are also slightly less acidic - diets that are more acidic have been linked to more rapid progression of CKD. Increased intake of fruits and vegetables is highly encouraged to boost alkalinity, while eating a high amount of animal proteins creates large amounts of acid in the body- so eating a plant-heavy diet, in essence, is a key strategy for helping slow the progression of CKD.

Takeaways

Overall, you should always aim to have a diet that is minimally processed, with whole foods whenever possible, and sprinkled with plant-based proteins where possible to help reduce the risks of worsening kidney function. Kidney disease is classified into 5 stages depending on your kidney function, stage 5 being lowest kidney function. Our nutrition needs will change depending on not only our level of kidney function, but also our bloodwork results. It is important to see your doctor and dietitian and get blood tests regularly to assess your needs and any changes needed in your diet as these may change often. For a complete list of what you should eat more of and what you should limit, you should talk with our dietitian during a detailed Medical Nutrition Therapy (MNT) session.