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Chronic kidney disease

The disease

Chronic kidney disease (CKD) encompasses a number of conditions that damage the kidneys and reduce their ability to keep the body healthy. The kidney’s primary function is to filter the blood, removing excess fluid and unwanted chemicals into the urine. As kidney disease worsens these wastes can build up in the blood stream and contribute to multiple complications such as high blood pressure, anaemia and weak bones. In addition, kidney disease significantly increases the risk of heart disease, with a two to three-fold greater risk of cardiac death than people without CKD.

Approximately 1 in 3 Australians are at risk of CKD and 1 in 10 people in both Australia and New Zealand have indicators of CKD in their blood and urine tests. Because 90% of kidney function can be lost before symptoms manifest, only 10% of people with CKD are aware they have this condition. This means that over 1.5 million Australians and 400,000 New Zealanders are unaware they likely have CKD.

Prevention, early detection and treatment are especially important for kidney disease because chronic kidney damage is most often permanent, requiring the use of dialysis or transplantation once they have entirely failed.

The cause

The two most common causes of CKD are diabetes and high blood pressure, which are responsible for up to two-thirds of cases. These conditions in turn are often caused by the highly processed, energy dense Western diet.

In those with CKD due to other conditions (such as auto-immune diseases, polycystic kidneys or malformations from birth), a standard Western diet still contributes significantly to chronic kidney damage and therefore plays a major role in the progressive worsening of kidney function.

The nutrition prescription

Whole food plant-based diets have been shown to be highly effective in both prevention and treatment of type 2 diabetes, high blood pressure and heart disease. This means it directly addresses the root cause of the majority of CKD cases and the primary cause of death in patients with kidney disease.[1]

In addition, the standard western diet is high in protein and acid load, both of which place extra stress on the kidneys.[2] Studies have found that consumption of a diet low in animal protein helps to keep kidney disease from worsening with time, thus delaying or preventing the need for dialysis or transplantation.[3][4] In fact, one study found that replacing just one daily serve of red meat with soy and legumes could reduce the risk of reaching end-stage kidney disease by 50%.[5]

Whole plant foods also contain phytates that bind to phosphate, thereby significantly reducing its gut absorption compared to highly processed or animal foods.[1] This is important because in kidney disease phosphate can build up in the blood and cause harm to bones and blood vessels, leading to an increased risk of death.


Medical supervision of diet change is essential

If you have kidney disease and want to transition to a plant-based diet, it is essential to discuss this with your physician first and proceed under medical supervision. Potassium monitoring may be advised, and medication needs can change quickly with the adoption of a whole food plant-based diet.


Video overview from NutritionFacts.org

Further resources

National Kidney Foundation

National Kidney Foundation (US): resources and guidance on the benefits of a plant-based diet for kidney health and its role for patients with kidney disease, plus links and tips for patients starting to explore plant-based diets.

Vegetables

Interview with renal nutrition expert Deborah Clegg, PhD: Written Q&A-style interview by US registered dietitian, Sharon Palmer, exploring how kidney disease can be managed with a plant-based diet.

FAQs

The kidneys help to keep the right amount of potassium in the body and people with kidney disease are at risk of high potassium levels in the blood. High potassium levels are serious as they can cause irregularities in heartbeat and even sudden death.

People with kidney disease are often recommended to avoid foods with particularly high potassium content, including some fruits and vegetables. Fortunately, plant foods contain natural alkali which helps to maintain normal potassium levels. [6] In addition, regular consumption of a high fibre diet prevents constipation and assists the body to remove excess potassium through the gut. [6]

If you have kidney disease and want to transition to a plant-based diet, it is important to discuss this with your physician first and consider monitoring your potassium levels initially. If you do experience high potassium levels there may be some simple adjustments that can be made to certain medications or foods to help with the transition.

Kidney stones form when normally soluble material in the urine is in such excess that they form crystals, slowly enlarging with time. Other factors, such as how acidic the urine is, increase the chances of stones forming. The most common kidney stones are made of calcium oxalate, calcium phosphate or uric acid.

A whole food, plant-based diet helps to reduce the risk of kidney stones in multiple ways, such as: [7]

  • More alkali urine and therefore a lower risk of both calcium and uric acid based crystals forming.
  • Lower amounts of uric acid levels in the urine, due to low animal protein intake.
  • Lower amounts of calcium in the urine due to low salt intake.

In fact, in a randomised trial of people with recurrent kidney stones, a diet low in animal protein and salt, compared to low-calcium diet, reduced the risk of further stones forming by more than 50%.[8]

[1] Chauveau P, Koppe L, Combe C, Lasseur C, Trolonge S, Aparicio M. Vegetarian diets and chronic kidney disease. Nephrol Dial Transplant. 2019;34(2):199-207. doi:10.1093/ndt/gfy164
[2] Fouque D, Aparicio M. Eleven reasons to control the protein intake of patients with chronic kidney disease. Nat Clin Pract Nephrol. 2007;3(7):383-392. doi:10.1038/ncpneph0524
[3] Nezu U, Kamiyama H, Kondo Y, Sakuma M, Morimoto T, Ueda S. Effect of low-protein diet on kidney function in diabetic nephropathy: meta-analysis of randomised controlled trials. BMJ Open. 2013;3(5):e002934. Published 2013 May 28. doi:10.1136/bmjopen-2013-002934
[4] Hahn D, Hodson EM, Fouque D. Low protein diets for non-diabetic adults with chronic kidney disease. Cochrane Database Syst Rev. 2018;10(10):CD001892. Published 2018 Oct 4. doi:10.1002/14651858.CD001892.pub4
[5] Lew QJ, Jafar TH, Koh HW, et al. Red Meat Intake and Risk of ESRD. J Am Soc Nephrol. 2017;28(1):304-312. doi:10.1681/ASN.2016030248
[6] St-Jules DE, Goldfarb DS, Sevick MA. Nutrient Non-equivalence: Does Restricting High-Potassium Plant Foods Help to Prevent Hyperkalemia in Hemodialysis Patients? [published correction appears in J Ren Nutr. 2016 Nov;26(6):416]. J Ren Nutr. 2016;26(5):282-287
[7] Heilberg IP, Goldfarb DS. Optimum nutrition for kidney stone disease. Adv Chronic Kidney Dis. 2013;20(2):165-174. doi:10.1053/j.ackd.2012.12.001
[8] Borghi L, Schianchi T, Meschi T, et al. Comparison of two diets for the prevention of recurrent stones in idiopathic hypercalciuria. N Engl J Med. 2002;346(2):77-84. doi:10.1056/NEJMoa010369

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