One of the best-known coconut water benefits, an uncommonly high amount of potassium, is also the main reason that drinking too much coconut water can cause harm.
In a case study titled “Death by Coconut,” published in Circulation, Justin Hakimian, MD, and his colleagues at the Department of Cardiology, New York Hospital Queens, describe the case of a 42-year-old previously healthy man who developed dangerously high potassium levels that led to fainting and abnormal heart rhythms after drinking a large amount of coconut water.
The man had been playing tennis outdoors all day in temperatures in excess of 90° F. He reported drinking a total of eight 11-ounce bottles of coconut water throughout the day. He experienced a sudden onset of lightheadedness and briefly lost consciousness. Afterward, he complained of weakness and lightheadedness and was brought to the emergency department by ambulance. He was disoriented and warm and, most importantly, had a very low blood pressure and heart rate.
Dangers of too much potassium
This unfortunate man was experiencing the classic signs of too much potassium in the blood. The body needs a delicate balance of potassium to help the heart and other muscles work properly. Most Americans consume too little potassium, which is mostly found in fruits and vegetables. Nevertheless, consuming a large amount in a relatively short period of time can lead to dangerous, and possibly deadly, changes in heart rhythm.
In fact, high potassium (hyperkalemia) is a common cause of life-threatening heart rhythm changes, including ventricular fibrillation, an emergency condition in which the lower parts of the heart flutter rapidly instead of pumping blood. If extremely high potassium levels in the blood remain untreated, the heart may stop beating, causing death.
The Institute of Medicine has set an adequate intake for potassium at 4,700 mg/day for adults, but they have not set an upper limit. Therefore, it is not clear exactly how much potassium can be taken safely. However, as you just learned, very high doses of potassium can be deadly.
Causes of high potassium
Potassium levels can become dangerously high from excessive intake, decreased excretion, or both. It can be particularly dangerous to consume high amounts of potassium when you have a certain medical condition or take any number of medications that also lead to high potassium levels in the blood. Causes of high potassium levels include the following:
- kidney disease
- medications including ACE inhibitors, beta-blockers, and some antibiotics like penicillin
- uncontrolled diabetes
- Addison’s disease (adrenal failure)
- burns and trauma
- breakdown of red blood cells (hemolysis)
- breakdown of muscle tissue (rhabdomyolysis)
In the case above, the man was also found to have muscle tissue breakdown (rhabdomyolysis). This can occur from muscle exertion, including from strenuous exercise, endurance exercise, and exercise in hot and humid conditions. Rhabdomyolysis commonly causes kidney damage. His doctors estimated that he ingested about 5,500 mg of potassium from his eight servings of coconut water. This amount of potassium, combined with the potassium that was likely released from his muscle fibers after prolonged exercise, was enough to hospitalize him.
Fortunately, after a three-day hospital stay and a temporary pacemaker, the man recovered. His potassium levels returned to normal and his heart began working properly again, as did his muscles and kidneys, which had gone into acute failure.
People can suffer from too little potassium as well.
The high potassium content of coconut water: benefits and risks
This is not the only published report of dangerously high potassium levels caused by drinking too much coconut water. It is a good lesson that too much of a good thing, even if it’s all natural, isn’t always safe. Anyone with a heart condition or kidney disease needs to avoid overdoing it with coconut water and talk to their doctor about how much potassium is safe to consume. Coconut water’s electrolytes and concentration just are not balanced enough to make it a great rehydration solution in extreme cases.
Most people have no reason to fear coconut water. Benefits of this all-natural, uncommonly nutritious beverage are great: coconut water is an excellent way to quench your thirst, boost hydration, and increase your intake of important vitamins, minerals, and phytonutrients. It even helps treat high blood pressure, if needed. Just limit your intake to a few servings a day.
Use good judgment and remember that for non-athletes, plain water is the beverage of choice during and after a daily workout.