Does soaking potatoes remove potassium? It can, but soaking alone may have a modest or inconsistent effect. Cooking in water and throwing that water away generally removes more potassium than soaking, though the amount varies by vegetable and preparation. These methods can help you lower potassium in a serving; they do not tell you how much potassium you personally need to avoid.
Does Soaking Potatoes Remove Potassium?
Potassium can move from cut food into surrounding water. Cutting a vegetable into smaller pieces exposes more surface area, which may help leaching, but there is no single cut size, soaking time or recipe proven to produce a specific potassium level in potatoes. Results from other tubers offer context, not a precise estimate for your potato serving.
In a 2022 study, Deborah Barbosa Vahia de Abreu and colleagues tested 20 foods commonly eaten in Brazil. They soaked samples in hot water for 5–10 minutes, using five parts water to one part food. Potassium fell by 10–20% in the tuber category, compared with 30–39% in non-leafy vegetables and 40–49% in leafy greens. The study did not report that tuber figure as a potato-specific result, so it should not be treated as a guaranteed reduction for potatoes or for a different soaking method.
Plain soaking is not always effective. In Uganda, J Asiimwe and colleagues tested matooke, a local staple banana, and found that soaking alone did not appear to lower its potassium. Boiling reduced potassium in the food, while more accumulated in the cooking water. Matooke is not a potato, but the finding illustrates why results from one food cannot automatically be applied to another.
Boiling And Discarding The Water Usually Leach More
A 2021 review by R Aparecida Borges Batista and colleagues compared 65 articles on food preparation methods, covering studies published from 1976 to May 2020. Across food groups, cooking in water and soaking tended to reduce potassium more than dry-heat methods such as steaming or oven cooking. The authors also noted that studies used varied methods and often lacked complete, standardized data. The review supports the general value of water-based preparation, not a reliable percentage for every vegetable.
Research by Montserrat Martínez-Pineda and colleagues measured potassium in green beans and chard prepared in different ways, including fresh, frozen and preserved samples. They found that reductions depended on both the vegetable and the processing method; in many cases, ordinary cooking achieved a meaningful reduction. That is a useful reminder that an elaborate double-cooking routine is not necessarily needed for every vegetable—but the study does not establish one universal result.
In practical terms, boiling vegetables in plenty of water and discarding the water gives potassium somewhere to leach into. If you reuse that liquid in soup, sauce or gravy, some of the potassium that left the vegetables goes back into the meal. Chopping, soaking, changing the water and then boiling may increase water contact, but the research does not establish one best protocol for every food. Follow the preparation approach your renal dietitian recommends, and avoid assuming that a particular method makes a food potassium-free.
Lower Potassium Can Mean Losing Other Nutrients, Too
Water-based cooking can carry other water-soluble nutrients, including vitamin C and some B vitamins, into the cooking liquid. Soaking and boiling may also change texture and flavor. The goal is not necessarily to remove as much potassium as possible: it is to choose a preparation that fits your needs while keeping meals varied and enjoyable.
Your Potassium Limit Depends On More Than A Food Table
Chronic kidney disease does not automatically mean you need the same potassium restriction as someone else with CKD. Blood potassium levels, kidney function, medicines and other aspects of your health matter. A 2023 practice review by Helen L. MacLaughlin and colleagues noted that dietary restriction has limited direct trial evidence as a treatment for high blood potassium. That uncertainty matters: leaching changes the potassium content of a food, but it does not prove that a particular diet or cooking method will control your blood level.
Ask your clinician or renal dietitian whether you need a potassium limit and, if so, what target and preparation methods make sense for you. They can help you weigh food choices and lab results rather than relying on a blanket list. For broader context, read more about understanding and managing chronic kidney disease. If you have concerns about a potassium result or a prescribed diet, discuss them with your care team before making major changes.