Clinicians and their patients with kidney disease are now getting new guidance on potassium and phosphorus additives, two nutrients of growing concern in chronic kidney disease (CKD) management. In September, The American Society of Nephrology (ASN) published its latest Kidney Health Guidance (KHG), addressing the impact of these additives on hyperkalemia and CKD-mineral and bone disorders. The guidance provides clinicians with practical strategies to help patients identify and manage foods containing potassium and phosphorus additives.

“This guidance is the first effort of its kind that targets an important problem that people with CKD face,” said Annabel Biruete, PHD, RD, assistant professor, Department of Nutrition Science at Purdue University in West Lafayette, Indiana, and member of the ASN KHG Workgroup on Food Additives. “Potassium and phosphorus food additives are ubiquitous in the food supply, and recent evidence suggests that they are highly absorbed, posing a problem for people with CKD who are at high risk of hyperkalemia and/or those with CKD-mineral and bone disorder.”

Biruete emphasized that increasing awareness alone is not sufficient; patients need to be better equipped to manage their nutrition. Potassium and phosphorus additives are ubiquitous yet often hidden in the food supply, and their impact may become more acute as kidney disease progresses. The guidance comes amid a surge in processed food consumption and recommendations from the World Health Organization and the US FDA to replace sodium with potassium-enriched salt substitutes.

Reducing Confusion About Phosphorus Additives

The KHG Workgroup concluded that phosphorus additives offer no health benefits for patients with CKD and should be avoided altogether. They warn that excessive phosphorus intake, even without overt hyperphosphatemia, may still pose health risks. By contrast, potassium additives may be potentially beneficial and should be restricted on an individualized basis depending on a patient’s hyperkalemia risk.

The KHG Workgroup cited the significant disconnect between the widespread use of additives and the limited information available through nutrient databases, food labels, and regulatory frameworks, an obstacle that makes it difficult for both patients and clinicians to make informed food choices.

“We recognized that the risk profiles between potassium and phosphorus are different in terms of acute vs chronic,” Biruete told Medscape Medical News. “The strategies that the guidance developed are intended to help clinicians provide education and counseling based on the risk profile, patient assessment, patient motivation, and clinical expertise.”

The guidance also emphasizes the importance of access to healthy food options and social support frameworks to any long-term dietary strategy in patients with kidney disease. Clinicians are encouraged to consider patients’ medical conditions, motivation, health literacy, and access to relevant resources.

Biruete noted several areas for improvement. “The information provided in the food label does not include the quantity of phosphorus, and only phosphorus additives are included in the ingredient list,” she said. “While potassium is included in the food label, some studies suggest that it may be underestimated, and we do not know how much is coming from additives.”

Empowering Patients With Kidney Disease

The guidance also identifies future research opportunities, including randomized controlled trials comparing education strategies across varying health literacy levels, as well as studies evaluating the bioavailability of potassium and phosphorus additives in the CKD population and the effect of these additives on outcomes related to potassium and phosphorus homeostasis and balance.

“These guidelines are quite important to patients with kidney disease and providers who work with renal disease,” said Anna Herby, DHSc, nutrition education specialist at Physicians Committee for Responsible Medicine, Washington, DC. “Many kidney patients hear the blanket recommendations to limit phosphorus and potassium without understanding the nuances of what that means.”

Herby noted that patients may assume these limits apply only to natural foods such as beans or dairy products, whereas additives are often the bigger concern.

“By educating patients on the difference between these nutrients when coming from plant foods vs when they come from additives or animal products, patients can feel empowered to eat more plant foods, leading to improved health outcomes,” Herby told Medscape Medical News.

Biruete reported receiving research funding from KidneyCure, the US Department of Agriculture, the Ralph W. and Grace M. Showalter Research Trust, and Purdue AgSEED; receiving honoraria from Ardelyx and Fresenius Medical Care; serving, without compensation, on the editorial board of the Journal of Renal Nutrition and, previously, as part of the National Dairy Council NextGen Scientist Cohort. 

Herby reported having no financial disclosures concerning her comments. 

John Schieszer, MA, is an award-winning national journalist and podcast broadcaster of The Medical Minute. He can be reached at medicalminutes@gmail.com.