Dietary Control of Uric Acid in Chronic Kidney Disease – Renal and Urology News

Uric acid in patients with chronic kidney disease (CKD) seems to be a controversial and confusing topic. What comes first: increased uric acid or progression of CKD? Is it beneficial to reduce uric acid in those with CKD? If so, what is the best approach? These are but a few of the questions that have been asked over the years in relation to uric acid and CKD. A review of the recent research provides insight into the role of uric acid in the progression of CKD as well as common symptoms or complications and possible nutrition interventions to improve outcomes.

It is commonly known that about two-thirds of the uric acid in the body is removed through the urine. Initially it was thought that this was why those with CKD often have high uric acid levels. But accumulating evidence of uric acid’s role in oxidative stress, stimulation of the renin-aldosterone-angiotensin system, endothelial damage and dysfunction, and activation of inflammatory factors suggests that increased uric acid levels contribute to the progression of CKD as well as cardiovascular disease, increased blood pressure, and inflammation.¹

High uric acid has also been recently noted as a risk factor for progression and negative outcomes in patients with immunoglobulin A nephropathy, renal injuries associated with oxidative stress, and new-onset CKD in those with a kidney transplant.¹

Dietary Approaches Unclear

Traditional nutrition approaches related to increased uric acid levels are typically focused on reducing high purine foods to reduce symptoms of gout. Recent evidence, however, suggests that some foods low in purines are associated with increased uric acid levels and have lengthened the list of foods and beverages to avoid to include beer, wine, liquor, soft drinks, poultry, potatoes and meat.² Other studies in non-CKD patients have found that multiple types of diets seem to reduce uric acid levels, but they all have a common pattern of being higher in vitamins, minerals, fiber, high-quality protein, and unsaturated fatty acids.³ This contradicts the traditional renal diet of restriction because the traditional diet lacks a foundation of evidence, and recent studies and guidelines advocate for a more liberal and individualized diet.^4,5

There are no more blanket potassium restrictions, and even then, only after considering other possible root causes, such as metabolic acidosis, medications, or constipation. Additionally, consideration of phosphorus sources is also recommended (such as limiting phosphorus additives rather than the more poorly absorbed phosphorus from beans or whole grains).⁶

These new evidence-based recommendations liberate the dietary approach for those with CKD and embrace dietary patterns that support metabolic and cardiovascular health. The diets are nutrient dense, reduce renal acid load, and lower uric acid levels. Renal dietitians can provide insight into these newer and more individualized recommendations to ensure patient success.

Role of Supplements

In addition to medications and diet, supplements may also play a supportive role in reducing uric acid levels. Vitamin E, vitamin C, L-arginine, N-acetylcysteine, curcumin, and quercetin have shown benefit in patients with CKD and often are used in conjunction with traditional medications for lowering uric acid. These supplements have additional benefits that medications do not generally have, such as reducing oxidative stress and inflammation, supporting gut health, and improving tissue oxygenation with increased nitric oxide production.^1,2

Although not everything is known about uric acid and CKD, the correlation seems worth investigating in clinical practice. Regularly measuring uric acid levels to establish a baseline and observing changes in levels, symptoms, and the effect of interventions on outcomes can help better establish when it is beneficial to lower uric acid levels, and how to do it. Until then, nutrition interventions that support the kidney often seem to result in healthy uric acid levels. This provides an easy opportunity to provide practice-based evidence to design better studies that could support evidence-based practice.

Lindsey Zirker, MS, RD, is a renal dietitian who works with Kidney Nutrition Institute in Titusville, Florida. She specializes in autoimmune kidney disease and advanced practice medical nutrition therapy for patients with kidney disease.

References

1. Roumeliotis S, Roumeliotis A, Dounousi E, Eleftheriadis T, Liakopoulos V. Dietary antioxidant supplements and uric acid in chronic kidney disease: A review. Nutrients. 2019;11(8):1911. doi:10.3390/nu11081911
2. Gherghina ME, Peride I, Tiglis M, Neagu TP, Niculae A, Checherita IA. Uric acid and oxidative stress-relationship with cardiovascular, metabolic, and renal Impairment. Int J Mol Sci. 2022;23(6):3188. doi:10.3390/ijms23063188
3. Zhang Y, Chen S, Yuan M, Xu Y, Xu H. Gout and diet: A comprehensive review of mechanisms and management. Nutrients. 2022;14(17):3525. doi:10.3390/nu14173525
4. Biruete A, Jeong JH, Barnes JL, Wilund KR. Modified nutritional recommendations to improve dietary patterns and outcomes in hemodialysis patients. J Ren Nutr. 2017;27;(1):62-70. doi: 10.1053/j.jrn.2016.06.001
5. Campbell KL, Carrero JJ. Diet for the management of patients with chronic kidney disease; it is the not the quantity, but the quality that matters. J Ren Nutr. 2016;26(5):279-281. doi: 10.1053/j.jrn.2016.07.004
6. Ikizler TA, Burrowes JD, Byham-Gray LD, et al. KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update. AJKD.2020;76(3 Suppl 1):S1-S107. doi:10.1053/j.ajkd.2020.05.006