New Research on Dietary Potassium

Most people on dialysis are told to restrict their dietary potassium intake to prevent hyperkalemia, an elevated potassium level in the blood. Hyperkalemia can lead to arrhythmia and sudden cardiac death. However, there are limited studies that focus on dietary potassium intake and hyperkalemia. A recent article in the Journal of Renal Nutrition studied dietary potassium intake in hemodialysis patients and death risk.¹

Potassium and Why It Is Important

Potassium is an important electrolyte in the body needed for muscle contractions and nerve conduction.¹ It plays a crucial role in proper heart function. Healthy adults are encouraged to consume 4,700 mg of potassium daily. Certain fresh fruits and vegetables are high in potassium, as well as vitamins and dietary fiber. The Dietary Approaches to Stop Hypertension (DASH) diet is high in potassium (4,500 mg/day) and has been associated with improved control of hypertension and diabetes, which improves cardiovascular risk.

Dialysis patients often have hypertension and/or diabetes. However, due to kidney failure, potassium can accumulate in the blood and potentially lead to hyperkalemia. To help prevent hyperkalemia and its risks, current recommendations are for most dialysis patients to limit potassium intake to 2,000 to 3,000 mg daily.

The New Research

In a new study published in the Journal of Renal Nutrition, the authors point out that to their knowledge, there has only been one prior study that looked at dietary potassium intake and death risk in hemodialysis patients. This 2010 study reported higher dietary potassium intake was associated with higher death risk.²  To further investigate this finding, the new research authors completed their own study that focused on dietary potassium intake and death risk.

The study included 415 hemodialysis patients from 16 outpatient dialysis facilities in Southern California. A food frequency questionnaire (FFQ) was used to determine dietary potassium intake. Based on the results of the FFQ, patients were divided into groups. Those with the lowest dietary potassium intake were placed in group 1 (average of 543 mg/day), moderate intake in group 2 (average of 1,234 mg/day), and highest intake in group 3 (average of 2,606 mg/day). Patients were followed from October 2011 to March 2015. Those in group 1, the lowest dietary potassium intake, had 2.5 times higher death risk compared to the other two groups. This study is the first to find that excessively low dietary potassium intake in dialysis patients is associated with higher death risk.

The authors state that those in group 1 had higher death risk independent of their sociodemographic, comorbidities, dialysis treatment, laboratory and nutritional characteristics. However, it is important to note that along with low potassium intake, those in group 1 had much lower calorie and protein intake as well. Group 1 had a median intake of 453 calories per day and median protein intake of 20 grams per day compared to group 2 of 1,004 calories and 45 grams protein per day, and group 3 of 1,731 calories and 82 grams protein per day. This could suggest that consuming less protein and calories per day in addition to a very low potassium intake, may contribute to the increased death risk.  The authors conclude that further studies are needed to fully understand the impact of excessive dietary restrictions on dialysis patients and mortality.

Takeaway

Potassium plays a vital role in the body. However, kidney disease affects how the body maintains potassium levels in the blood and there is concern for developing hyperkalemia. Most dialysis patients are told to restrict their dietary potassium to prevent hyperkalemia. The exception is those have low potassium levels on lab results. This study found that very low potassium intake can be dangerous and is associated with increased death risk. Group 3 included patients with the highest dietary potassium intake ranging from 1.902 to 2,919 gm, with an average of 2,606 mg per day. This is within the current recommendation for dialysis patients of 2,000-3,000 mg/day. The results from this study suggest that patients should be careful not over-restrict their potassium intake, especially when calorie and protein intake is inadequate. Dialysis patients should work with their physician or registered dietitian to determine the appropriate amount of potassium they should consume daily and for guidance on which foods are high and low in potassium.

References:

1. Dietary Potassium Intake and Mortality in a Prospective Hemodialysis Cohort. Yoko Narasaki, et al., Journal of Renal Nutrition, October 27, 2020. DOI: https://doi.org/10.1053/j.jrn.2020.05.008

• Dietary Potassium Intake and Mortality in long-term hemodialysis patients. Nazanin Noori, et al., American Journal of Kidney Diseases, Volume 56, p338-347, 2010. https://pubmed.ncbi.nlm.nih.gov/20580474/

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This article is for informational purposes only and is not a substitute for medical advice or treatment. Consult your physician and dietitian regarding your specific diagnosis, treatment, diet and health questions.