An Italian paper released as a preprint* on June 18 documented a very high rate of hypokalemia, or low blood levels of potassium, among hospitalized COVID-19 patients.
Among 290 hospitalized but non-critical COVID-19 patients, 41% had hypokalemia.
In roughly a third of them, urinary potassium was measured. In that subset, 96% of the patients had elevated urine potassium. This shows that the blood levels of potassium were low because the potassium was being lost in the urine.
In 77% of these patients, the hypokalemia could be attributed to medications they were on, diuretics and corticosteroids. However, medications could not explain the hypokalemia in the remaining 23%.
The cause of the increased urinary potassium loss is unclear. There are a few possibilities:
In the 23% who weren't taking potassium-wasting medications, 90% had acid-base disturbances. Acid-base disturbances can cause potassium loss, and potassium loss can cause acid-base disturbances, so which is causing which is unclear.
Kidneys are a major expresser of ACE2, the entryway of the virus into cells, and the virus has been found in urine, suggesting the kidneys may get infected. If so, the virus may increase potassium loss by damaging the kidneys.
The virus may also cause loss of ACE2, which would increase angiotensin II, which would in turn increase aldosterone, a hormone that causes urinary potassium loss.
The low potassium was not associated with the severity of COVID-19 outcomes, but low potassium levels can cause heart palpitations and arrhythmias, and when they are extreme, the arrhythmias can be fatal. Many COVID-19 patients wind up on hydroxychloroquine, which can cause arrhythmias, and low potassium levels could increase the risk of those arrhythmias.
Although low dietary potassium intake is rarely the main driver of hypokalemia, low potassium intake does in fact make us more vulnerable to hypokalemia from virtually any other cause. Most people do not consume enough potassium, and emphasizing adequate potassium will most likely help reduce the risk of developing hypokalemia.
This should not be seen as a guarantee of avoiding hypokalemia. It is simply a protection to reduce the risk.
What is adequate?
From 2005-2019, the official recommendations were 4.7 grams of potassium per day. They have since been reduced to 2.3 grams per day for adult women and 3.4 grams per day for adult men. On the other hand, by some estimates our hunter-gatherer ancestors consumed up to 11 grams per day. I personally consider the newer official recommendations to be minimums, and 4.7-11 grams per day to be the optimal range.
I have produced a number of useful resources on obtaining adequate potassium.
The first I'll share is an excerpt from Testing Nutritional Status: The Ultimate Cheat Sheet that broadly outlines three general strategies to get enough potassium:
Three options for constructing a potassium-rich diet are provided below: 1) a diet very rich in fruits and vegetables, 2) a low-fat diet that is low in grains and free of refined carbohydrates, and 3) a low-carbohydrate, high-fat diet that emphasizes vegetables with high ratios of potassium to net carbs.
For all the foods below, it is important to consume them raw or to consume the cooking water and juices. Otherwise, significant amounts of potassium will be lost.
Diets Rich in Fruits and Vegetables
Fruits generally provide 100-500 mg of potassium per 100 gram serving, and vegetables generally provide 200-1000 mg per 100 gram serving. When adjusted per calorie, vegetables are extremely rich in potassium. For example, 300 Calories of spinach provides over 7 grams of potassium. Following the official recommendations to consume five to nine servings of fruits and vegetables per day and selecting them for their potassium content can easily provide the recommended amount of potassium, regardless of the rest of the diet.
Diets Low in Fat, Moderate in Grains, and Free of Refined Carbohydrates
Alternatively, reducing the fat content of the diet, moderating grains, and eliminating refined carbohydrates can allow the broad selection of alternative foods to fulfill the potassium requirement. 300 Calories of butter contains only 10 milligrams of potassium. 300 Calories of enriched white flour contains 91 milligrams of potassium. While much better than butter, this is only a quarter as potassium-rich as whole wheat flour, which at the same caloric load provides 358 milligrams of potassium. Nevertheless, 300 Calories worth of beans or potatoes provides close to 1.5 grams of potassium each, which is about quadruple that provided by whole wheat. 300 Calories of fat-free milk provides 1.4 grams of potassium, whereas the same caloric load of whole milk provides only 715 milligrams, about half as much. 300 Calories of sirloin steak with all the fat trimmed off provides 700 mg of potassium. By contrast, beef tallow does not contain any potassium. In a single large egg, there are 67 mg of potassium, 80% of which is in the white. For each 300 Calories, egg whites provide over 1 gram of potassium, while whole eggs provide only 281 milligrams and egg yolks provide a dismal 103 milligrams.
Low-Carbohydrate, High-Fat Diets
It is possible to eat a low-carbohydrate, high-fat diet with adequate potassium, but it requires much more attention to food selection. 75 grams of protein obtained from meat will provide about 750-1000 milligrams of potassium. 150 grams of protein from meat will provide about 1.5-2 grams of potassium. The following is a list of mg potassium per gram net carb (total carbohydrate minus fiber) in some of the best choices for vegetables: watercress, 431; spinach, 399; purslane, 329; mustard greens, 221; bamboo shoots, 178; arugula, 176; red leaf lettuce, 170; celery, 144; white mushrooms, 138; green leaf lettuce, 129; zucchini, 119; Chinese cabbage, 119; asparagus, 106; common cabbage, 79; iceberg lettuce, 71; tomatoes, 66. If one were to eat 100 grams of each of these vegetables per day, this would yield 4.9 grams of potassium and less than 32 grams of net carbs. The lean portion of the protein would bring the total to anywhere from 5.6 to 6.9 grams of potassium and the remainder of the diet could be fat.
Since the simplest ways to get enough potassium tend to involve a lot of plant foods, and often involve too many carbohydrates for those on very low-carbohydrate diets, I produced two resources for the low-carbohydrate and carnivore communities (please note that I am neither low-carb nor carnivore myself):
Getting Potassium on Low-Carb Diets: The Database
This database allows you to rank over 4,500 foods by their potassium-to-net-carb ratio, that is, how much potassium they have relative to their non-fiber carbohydrates.
Getting Potassium on Carnivore Diets: The Database
This database allows you to rank over 2,500 carnivore foods by their potassium on a basis of per 100 grams of food, per 100 Calories, per 100 grams of protein, or per gram of sulfur amino acids. This addresses two concerns that are particularly important for carnivores: many of these foods are high in calories, so it can be hard to get enough potassium without overeating; many of these foods are high in sulfur amino acids, which have an acidifying effect that cancels out some of the alkalinizing effects of the compounds associated with potassium within a food.
I've produced some short videos on getting enough potassium from foods and supplements.
Finally, my free Vitamins and Minerals 101 course contains three lessons totaling 42 pages on salt and potassium. You can sign up to receive the course by email or Facebook messenger here. The lessons come out once each day, and the salt and potassium lessons are lessons 25, 26, and 27.
You can get the salt and potassium lessons immediately if you sign up for Vitamins and Minerals 101 Premium. You get lifetime access for free if you pre-order the Vitamins and Minerals 101 book, which I will be finishing and releasing as soon as it is clear the COVID-19 crisis has subsided. You also get free access if you are a member of the CMJ Masterpass, a membership program aimed at helping you save money if you have significant health and wellness expenditures. Being a member also gets you 30% off pre-orders of the paperback and 50% off pre-orders of the digital versions of the book.
The Bottom Line
There is no reason to believe that potassium protects against COVID-19 infection or severity. However, it appears that severe cases of COVID-19 can cause hypokalemia, and this could cause heart palpitations and arrhythmias, could in rare cases be fatal, and could worsen the risk of heart trouble from hydroxychloroquine. While the exact mechanisms of the hypokalemia are not clear, it is caused by urinary potassium loss in most cases, and getting enough potassium in the diet will offer some protection against it.
Stay safe and healthy,
Chris
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Disclaimer
I am not a medical doctor and this is not medical advice. I have a PhD in Nutritional Sciences and my expertise is in conducting and interpreting research related to my field. Please consult your physician before doing anything for prevention or treatment of COVID-19, and please seek the help of a physician immediately if you believe you may have COVID-19.
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*Footnotes
* The term “preprint” is often used in these updates. Preprints are studies destined for peer-reviewed journals that have yet to be peer-reviewed. Because COVID-19 is such a rapidly evolving disease and peer-review takes so long, most of the information circulating about the disease comes from preprints.