Potassium Bioavailability: Re-examining the Evidence

The 2024 KDIGO guidelines recommend advising patients who have a history of hyperkalemia to limit the intake of foods rich in bioavailable potassium. These guidelines highlight processed foods as highly bioavailable, but do not provide any further details. Therefore, the purpose of this review was to summarize the literature on what is known about potassium bioavailability in foods.

With this iterative, snowball, scoping review, the authors sought to summarize all literature that provided sufficient data to make interpretations regarding potassium bioavailability. The inclusion criteria were articles that reported information about potassium intake and urinary potassium excretion, potassium balance studies, animal studies, and in vitro bio-accessibility models. Exclusion criteria were non-English language articles or articles which exclusively tested potassium bioavailability of medications or supplements.

This iterative search process yielded a total title screen of 2180 articles. 114 abstracts were screened, 45 full text articles reviewed, and 26 articles met inclusion criteria. Most studies estimated potassium bioavailability using 24-hour urinary potassium excretion. However, inclusion of potassium balance studies suggested this is an insensitive and unreliable biomarker of potassium bioavailability. Balance studies suggested that potassium bioavailability ranged from 88-94% regardless of the source of dietary potassium.

Current human models using 24-hour urinary recovery to estimate potassium bioavailability are insufficient to provide meaningful results and should not be used as a surrogate marker of potassium bioavailability. Frequently cited potassium bioavailability estimates of 50-60% for fruits and vegetables, 70-90% for animal-based foods, and 100% for additives are not fully supported when the breadth and quality of the available evidence is considered. Further studies using more fulsome methods to assess potassium bioavailability are needed.