Potatoes and Kidney Disease: The Potassium Dilemma

Can people with chronic kidney disease (CKD) eat potatoes? What about bananas or tomatoes?  All of these foods are notorious for being high in potassium.  Kidney patients are often told to stay away from them.  I have good news! Patients with kidney disease CAN enjoy these high potassium foods.  However, how often these foods should be eaten depends.  Keep reading to learn more about potatoes and kidney disease.

What is Potassium?

Potassium is one of the most abundant electrolytes in our bodies.  Our body would not work without it!  Potassium is in every single cell in our body and helps our cells maintain proper fluid balance and nutrient transport1.

Potassium is important for healthy nerve function and muscle contraction including arguably our most important muscle, the heart!1

Where Does Potassium Come From?

Our bodies can’t make potassium, so we rely on our diet for all the potassium we need.  Almost every food has some potassium in it.  Fruits and vegetables generally contain the highest amount of potassium.  Potatoes, tomatoes, oranges, and bananas are probably the most well-known high potassium foods.

We can also get potassium from dietary supplements.  However, I don’t usually recommend relying on supplements to get potassium because a healthy diet can give you all the potassium you need.  Plus, fruits and vegetables provide many benefits other than potassium!

Potassium Health Benefits

Eating enough potassium has been shown to help high blood pressure and heart health.  In fact, one of the most well researched diets for blood pressure, the Dietary Approaches to Stop Hypertension (DASH) diet, is so good at lowering blood pressure because of its high potassium level.2

The DASH diet is very high in fruits and vegetables (up to 10 servings per day), nuts/seeds, dairy and whole grains.  A DASH diet is a very healthy choice for people with kidney disease who have good kidney function (a Glomerular Filtration Rate, GFR of 30ml/min or more).

Check out my DASH handout or read more about the DASH diet.

Potassium and Chronic Kidney Disease

The problem with potassium and chronic kidney disease (CKD) comes from the fact that kidneys usually get rid of extra potassium in our urine.  Urine is the main way our kidneys excrete potassium.  If kidneys are not working as well as they should, they also cannot get rid of potassium as effectively.

If kidneys can’t get rid of potassium, potassium can build up in our bodies and cause harm.  High levels of potassium in the body is called hyperkalemia.  Around 10-20% of people with CKD will also have hyperkalemia and it is more likely as kidney function gets worse3More about hyperkalemia.

Side effects of hyperkalemia include4,5:

  • Weakness or tiredness
  • Numbness or tingling feeling
  • Difficulty breathing
  • Heart attack or abnormal heartbeat
  • Death

Other Factors That Affect Potassium

Medications

Some medications can cause high potassium.  ACE-inhibitors  (lisinopril, enalapril, quinapril, benazepril) and ARBs (irbesartan, losartan, Olmesartan, valsartan) are commonly prescribed in CKD patients and can make hyperkalemia worse.

ACE and ARBs are common in people with CKD because they help keep blood pressure under control and can reduce how much protein is in urine.  They are especially common for people with both CKD and diabetes.  ACE and ARBs have been shown to slow the progression of kidney disease in people with diabetes and are recommended by the National Kidney Foundation6. Even though these medications can worsen potassium levels, it is very important to keep taking them if recommended by your doctor! Talk to your doctor if you are concerned.

Blood Sugar

High blood sugar can worsen hyperkalemia.  If you have diabetes, it is important to do everything you can to keep your blood sugar at a healthy level to protect your kidneys, while also keeping potassium within a healthy range.  A healthy diet for diabetes is crucial to help keep blood sugar under control.

Acidosis

Too much acid in your blood (a condition called acidosis) can also worsen high potassium levels.  Your kidney doctor regularly measures how much acid in is your blood and might prescribe medications to reduce acid, such as a medication called sodium bicarbonate.  Diet can also affect the amount of acid in your body.

How Much Potassium Do You Need?

So, we know that potassium is good for us, but if your kidneys aren’t working as well as they should, you are at risk of hyperkalemia.  What is a person to do!? Can potatoes be part of a renal diet?  The answer depends on your lab values.

People with Normal Blood Potassium

Most people with kidney disease will fit into this category.  If your potassium level is normal (3.5-5.5mEq/L7), you do not need to cut back how much potassium you eat.  Potatoes and kidney disease do work together!  In fact, eating a diet rich in potassium could help control your blood pressure and reduce your risk for heart disease2.

The National Institutes of Health recommends adults eat 4,700mg of potassium per day1.  The average potassium intake in the United States is only about 2,000mg per day8, less than half of the recommended amount!  Most of us need to eat quite a bit more potassium than we are now.  Focusing on eating at least 5 servings of fruits and vegetables per day will help you reach that high potassium goal.

People with High Blood Potassium

If you consistently have too much potassium in your blood, more than 5.5mEq/L7 (aka hyperkalemia), you should reduce how much potassium you eat.  There is not a recommended amount of potassium people with hyperkalemia should eat.  Instead, it is best to just cut back how much potassium you eat.

I often recommend limiting high potassium foods to a set number of servings per week, depending on how high potassium levels are and how much my patient was eating before.  Some patients can tolerate one high potassium food per day, others can only handle one serving per week.  Your dietitian can help you figure out how much is right for you.

Your doctor typically checks how much potassium is in your blood when they check labs.  Check out what your potassium level is to figure out if you should be eating a lot of potassium or cutting back.  If you don’t have your lab results, call your doctor and ask!

Can I Still Eat Fruits & Vegetables?!

YES!  Common advice for people with high potassium is to avoid ALL fruits and vegetables.  THIS IS NOT NECESSARY!

Although fruits and vegetables are known for being high in potassium, there are many healthy choices for people with high potassium on a renal diet.  Completely avoiding fruits and vegetables could be harmful and put you at risk of malnutrition, micronutrient deficiencies and excess intake of other foods such as protein or carbohydrate.  Fruits and vegetables are a critical part of a healthy diet for everyone, especially people with kidney disease!

How to Follow a Low Potassium Diet

When you Google “what foods are high in potassium”, it can be overwhelming!  It can feel like ALL foods are high in potassium and there is nothing left to eat!  Good news: there are plenty of delicious, healthy foods you can eat even if you need to limit potassium.

How to Build a Healthy Low Potassium Meal:

1) Make half of your plate fruits and vegetables.  Yes! You can still (and should!) eat LOTS of fruits and vegetables.  It is just important to choose mostly low potassium ones.  If you have diabetes, focus on making half your plate non-starchy vegetables.

2) Add some protein.  If you choose meat, poultry or fish for your protein, keep your portion to 3-6oz (or about half the size of the palm of your hand).  Plant proteins like beans, lentils, peas, or nuts can work here too!  Although these foods are sometimes classified as “high” potassium, they do not have much more potassium in them when compared to meat.  I encourage plant proteins on a low potassium diet as a replacement for meat in a meal.  But, having plant proteins in addition to meat could be too much potassium.

3) Add a healthy carbohydrate. Good choices are whole grain pasta, brown rice, whole grain bread, or wild rice.  Whole grains do have more potassium than white grains, but the benefits of fiber and other micronutrients outweigh the higher potassium.  If you have diabetes, be careful with portion size.

Potassium Foods List

This list only lists fruits and vegetables.  Know that most other foods have potassium as well, but if you follow the three tips for building a low potassium meal above, you should only need to focus on choosing low potassium fruits and vegetables.

Vegetable Potassium Food List

Low PotassiumHigh Potassium
AsparagusAcorn Squash
Bell PeppersArtichokes
Bok Choy Avocado
BroccoliBeets
CabbageButternut Squash
CarrotsBrussels Sprouts
CauliflowerGreens (turnip, collard, mustard)
Celery Kohlrabi
CornParsnips
CucumbersPotatoes (baked, mashed, boiled, French fries) Pumpkin
EggplantRutabaga
EndiveSpinach
Green BeansSweet Potato
Green PeasTomato (raw, juice, sauce)
Kale Zucchini
Lettuce
Mushrooms
Okra
Onions
Spaghetti Squash
Sugar Snap Peas
Turnips
Yellow Beans
Yellow Squash
Water Chestnuts

Fruit Potassium Foods List

Low PotassiumHigh Potassium
Apple (fresh, juice, applesauce)Bananas
ApricotsCantaloupe
BlackberriesDried Fruits
BlueberriesFigs
CherriesKiwi
Cranberries (fresh, canned, juice)Mango
Fruit cocktailNectarine
Grapes (fresh, juice)Oranges (fresh, juice)
Honeydew MelonPapaya
LemonsPomegranate (fresh, juice)
LimesPrunes (fresh, juice)
Peaches
Pears
Pineapple (fresh, canned, juice)
Plums
Raspberries
Rhubarb
Strawberries
Tangerines
Watermelon

Potassium Foods List PDF

Dairy and Potassium

Dairy is moderately high in potassium.  Eating too much can contribute excess potassium.  Milk, yogurt and cheese are all moderately high.  Be careful to avoid large amounts of these foods.  For most of my patients, I recommend no more than 1 serving of dairy per day (1 cup milk, ¾ cup yogurt or 1oz cheese).  Rice milk can be a great low potassium substitute for cow’s milk.

Hidden Potassium

Extra potassium has found its way into our food supply as part of food additives in processed foods.  One study found that meat and poultry products labeled as “low-sodium” actually contained 44% more potassium than regular versions as a result of potassium additives9. The potassium is added in an effort to make the food more “heart-healthy”.  However, this extra potassium could be harmful for kidney patients.

As of January 2020, food manufacturers are required to start adding potassium to food labels, so this will help us figure out how much potassium is in our food.  However, I still recommend reading the ingredients on Nutrition Facts labels to be safe.  Look for the word “potassium” in ANY part of a word in the ingredients.

Potatoes and Kidney Disease: The Verdict

People with kidney disease CAN enjoy potatoes!  YAY!  This myth came to be because potatoes are high in potassium.  However, most people with kidney disease DO NOT need to limit potassium!  In fact, many people with kidney disease actually need to eat MORE potassium.

Some people with kidney disease, especially those with advanced stages of disease, do struggle with high blood potassium levels.  If this is you, you can STILL enjoy potatoes occasionally.  You just need to count them as one of your high potassium food choices.

A tip for those of you that REALLY love potatoes.  Boil your potatoes to reduce potassium by about half.  This will make potatoes much safer to eat for people with high potassium levels.

As always, check with your dietitian – who knows you much better than I do – to help figure out exactly how much potassium and how often you can enjoy high potassium foods.

Happy Eating!

Melanie

References

  1. Office of Dietary Supplements – Potassium. https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/. Accessed April 18, 2020.
  2. Sacks FM, Svetkey LP, Vollmer WM, et al. Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet. N Engl J Med. 2001;344(1):3-10. doi:10.1056/NEJM200101043440101
  3. Gilligan S, Raphael KL. Hyperkalemia and Hypokalemia in CKD: Prevalence, Risk Factors, and Clinical Outcomes. Adv Chronic Kidney Dis. 2017;24(5):315-318. doi:10.1053/j.ackd.2017.06.004
  4. Korgaonkar S, Tilea A, Gillespie BW, et al. Serum potassium and outcomes in CKD: insights from the RRI-CKD cohort study. Clin J Am Soc Nephrol CJASN. 2010;5(5):762-769. doi:10.2215/CJN.05850809
  5. High Potassium: Causes, Symptoms, and Diagnosis. Healthline. https://www.healthline.com/health/high-potassium-hyperkalemia. Accessed April 18, 2020.
  6. NKF KDOQI Guidelines. https://kidneyfoundation.cachefly.net/professionals/KDOQI/guidelines_bp/guide_11.htm. Accessed April 18, 2020.
  7. Rastegar A. Serum Potassium. In: Walker HK, Hall WD, Hurst JW, eds. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd ed. Boston: Butterworths; 1990. http://www.ncbi.nlm.nih.gov/books/NBK307/. Accessed April 18, 2020.
  8. Whelton Paul K. Sodium and Potassium Intake in US Adults. Circulation. 2018;137(3):247-249. doi:10.1161/CIRCULATIONAHA.117.031371
  9. Parpia AS, Goldstein MB, Arcand J, Cho F, L’Abbé MR, Darling PB. Sodium-Reduced Meat and Poultry Products Contain a Significant Amount of Potassium from Food Additives. J Acad Nutr Diet. 2018;118(5):878-885. doi:10.1016/j.jand.2017.10.025

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