Potassium and kidney diets: benefits and cautions
The renal diet….it’s confusing…and the rules don’t apply to everyone the same way. Today I want to look at potassium and who needs a restricted low potassium diet, who can benefit from eating more potassium-rich foods, and what the goals are for low, normal and high potassium.
The 2010 Dietary Guidelines for Americans includes a chapter on foods and nutrients to increase. Potassium is on this list because the average American diet does not include the recommended servings of fruit, vegetables, whole grains, milk and milk products. Research actually shows that a low sodium, high potassium diet helps reduce blood pressure and risk of stroke by 21%. Reduced risk of kidney stones and decreased bone loss are also listed as benefits of a high potassium diet.
What about kidney patients? The guidelines recommend that if you have kidney disease and/or if you take certain medications such as an ACE inhibitor or potassium-sparing diuretic, you should consult your health care provider for specific guidance about potassium. The next time you see your doctor or dietitian, have a conversation about potassium, your individual needs and if you require a limit on potassium-rich foods.
In general, if you have early kidney disease stages 1-3, you have normal potassium levels while consuming a regular, non-restricted potassium diet, and you are not taking medications that make you retain potassium, you most likely do not require a potassium restricted diet. As a matter of fact, a high potassium diet may help with blood pressure control.
Elevated potassium can show up in stage 3 chronic kidney disease, and is treated by a change in medications that cause potassium increase or by limiting high potassium foods. It’s important to track your potassium lab results and question your doctor and dietitian if you detect high or low values (normal potassium is 3.5-5.0 mEq/L). You also need to know the effects of medication change or low potassium diet, so ask for a potassium check after changes have been made. When kidney function declines to later stages 4 and 5 less potassium is removed due to kidney damage. When levels exceed 5.0 a low potassium diet will help reduce blood levels. In stage 5 CKD, end stage kidney disease, very little potassium is removed, particularly if there is very little urine output. Even a low potassium diet may not be enough to control potassium so dialysis is needed. High potassium is dangerous because it slows the heart. Very high levels can cause the heart to stop.
So how much potassium do you need? The Dietary guidelines recommend 4,700 mg a day as the Adequate Intake (AI) for adults. The Kidney Disease Outcomes Quality or KDOQI guidelines state that in stages 1-4, potassium should be correlated with lab values. For stage 5 , potassium is restricted, depending on the type of dialysis. For example, peritoneal dialysis (PD) patients do daily dialysis and often need a higher potassium diet. Hemodialysis patients who have 3 treatments a week need to restrict potassium to prevent high levels between dialysis treatments. A low potassium diet is generally 2000 mg a day, although some people can consume up to 3000 mg daily and maintain normal levels.
For a list of foods high in potassium, see my past post High Potassium Foods to Limit on the Kidney Diet to download the list or read the article Potassium and Chronic Kidney Disease, which lists high and low potassium foods.