Is a “Healthy” Diet Healthy for Dialysis Patients?

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Author:
James Matera, DO, FACOI
Medical Director of Population Health, CentraState Medical Center, Freehold, NJ

Citation:
Matera J. Is a “healthy” diet healthy for dialysis patients? [Published on February 20, 2019]. Consultant360.

It is well known that cardiovascular disease is the main cause of morbidity and mortality in hemodialysis patients, regardless of age, with the rate approaching 40%.¹ Coupled with a number of metabolic factors like phosphorous, parathyroid hormone, and fibroblast growth factor-23, which also influence cardiovascular risk in this patient population, it seems like the deck is stacked against dialysis patients.²

While diets comprised of 4 to 5 daily servings of fruits and vegetables are known to help improve cardiovascular and non-cardiovascular risks,³ patients on hemodialysis are often on restricted diets that limit their intake of fresh fruits and vegetables, primarily due to risks associated with potassium balance and hyperkalemia.

However, we still have to take non-cardiac risk factors, such as infection, cancers, and other comorbidities, into account in this patient population. Because diets rich in fruits and vegetables can have a positive impact on the aforementioned non-cardiac risks, we must ask: could these diets still play a role in lessening mortality risk among patients with end-stage renal disease (ESRD)?

In a recent article out of Sydney, Australia, the effects of diets high in fruits and vegetables were examined in hemodialysis populations across 11 countries.⁴ The study looked at 9757 adults on hemodialysis who had dietary data available for analysis, and followed them for almost 3 years. In that cohort:

• 26% of the patients died.
• The median intake of fruits and vegetables was less than 10 servings per week, which is substantially lower than the recommended 4 to 5 servings per day.
• Increasing the weekly intake to 17 servings had a positive effect on cardiovascular mortality, reducing the risk of all-cause mortality and death due to non-cardiac causes by 20%.
• Cardiovascular deaths did not change during this time.

This study did not show an appreciable change in potassium across the groups consuming 0 to 5, 5 to 10, and more than 10 servings of fruits and vegetables per week. Moreover, one limitation of the study was that it did not indicate which patients may have been taking potassium-lowering resins. In this patient population, potassium-binding resins like sodium polystyrene are used to help keep hyperkalemia under control. However, this is not best practice due to the adverse effects of these agents.⁵ Newer and safer agents have been introduced, but they have yet to be studied in the dialysis population. Also, phosphorous restriction is needed in dialysis patients to avoid the cardiovascular cascade leading to secondary hyperparathyroidism and its inherent cardiovascular risks.

In summary, more studies are needed to look at the potential benefits of allowing patients with ESRD to eat healthier diets rich in fruits and vegetables.⁵ Future research needs to focus on:

• Potential potassium-based issues like hyperkalemia
• Non-cardiac and cardiac mortality
• Potential impacts on other comorbidities like infection and cancer risks
• Phosphorous intake also needs to be taken into account in these studies

References:

1. USRDS 2017 Annual data report: atlas of chronic kidney disease and end-stage renal disease in the United States. National Institute of Diabetes and Digestive and Kidney Disease at the National Institutes of Health. https://www.usrds.org/2017/download/2017_Volume_1_CKD_in_the_US.pdf. Accessed on February 12, 2019.
2. Ärnlöv J, Carlsson AC, Sundström J, Ingelsson E, Larsson A, Lind L, Larsson TE. Serum FGF23 and risk of cardiovascular events in relation to mineral metabolism and cardiovascular pathology. Clin J Am Soc Nephrol. 2013;8(5):781-786. doi:10.2215/CJN.09570912.
3. Wang X, Ouyang Y, Liu J, Zhu M, Zhao G, Bao W, Hu FB. Fruit and vegetable consumption and mortality from all causes, cardiovascular disease and cancer: systematic review and dose-response meta-analysis of prospective cohort studies. BMJ. 2014;349:g4490. https://doi.org/10.1136/bmj.g4490.
4. Saglimbene VM, Wong G, Ruospo M, Palmer. SC, Garcia-Larsen. V, Natale P, et al. Fruit and vegetable intake and mortality in adults undergoing maintenance hemodialysis. Clin J Am Soc Nephrol. 2019;14(2):250-260. https://doi.org/10.2215/CJN.08580718.
5. Watson M, Abbott KC, Yuan CM. Damned if you do, damned if you don't: potassium binding resins in hyperkalemia. Clin J Am Soc Nephrol. 2010;5(10):1723-1726; doi:10.2215/CJN.03700410.