Coconut water has so much potassium that people with kidney disease can run into “life-threatening hyperkalemia” Dr. Micheal Greger
Coconut water has so much potassium that people with kidney disease can run into “life-threatening hyperkalemia”
So far, I’ve reviewed the evidence on coconut oil and coconut milk that suggests neither is good for you. But what about coconut water? When I first learned about athletes using coconut water as a natural Gatorade, I did a medical literature search for athletes and coconut, and only came up with this: a study of “canine athletes.” Turns out feeding drug- or bomb-sniffing dogs coconut oil can sometimes wipe out their ability to smell at all. But, what about coconut water and human athletes?
Studies on coconut water as an electrolyte-replacement beverage date back decades, when coconut water was compared to other beverages and found to be “more suitable.” But, the other beverages they compared it to were like Pepsi, Coke, Sprite, and 7Up. You don’t really know—until you put it to the test. It was found to help in cases of mild dehydration, due to childhood diarrhea, despite having an unbalanced “electrolyte composition”—by which they meant the sodium/potassium ratio was off.
Coconut water has so much potassium that people with kidney disease can run into “life-threatening hyperkalemia” (too much potassium in the blood) if they drink like two quarts of coconut water and don’t have normal kidney function—which would otherwise just flush the excess away. People may not realize coconut water has so much potassium. So, even if your doctor warned you about staying away from high-potassium foods, you may not realize and may run into problems. Even one quart a day may be too much for someone whose kidneys have been compromised by diabetes, for example. Cream of tartar is the same kind of thing. People don’t realize it’s like 20% pure potassium. So, when they listen to websites claiming it’s some “‘natural’ remedy,” even young people with healthy kidneys can run into problems if they take spoonfuls of the stuff—with cream of tartar overdose deaths dating back to the 1800s.
But, what about “rehydration after exercise with fresh young coconut water”? Yes, it can help replace fluid loss from diarrhea; what about fluid loss from heavy exercise? We didn’t know, until this study. 90 minutes at about 90 degrees Fahrenheit until they lost up to 3% of their body weight. Then, researchers had them drink coconut water, versus a sports beverage, versus just plain water—and, no significant difference in rehydration for any of them. Subsequent study findings were more mixed. Some showed a sports drink beat out water for hydration, but coconut water didn’t. Or, they both beat out water, but not each other. The reason athletes care about rehydration is that they care about performance. But, there had never been any studies on not just “measures of hydration,” but on “physical performance”—until this study.
They tested the water, vs. coconut water, vs. coconut water from concentrate, versus a standard sports drink. Then, they stuck people on a treadmill and timed how long they could go before they collapsed. And, they discovered “no significant difference” between any of them. Plain water did just as well as coconut water—in fact, even better, since those drinking the coconut water felt “more bloated,” with upset tummies. Now, this was all done at room temperature, about 70 degrees. What about instead at over 90 degrees Fahrenheit? Then, the coconut water did seem to beat out water. But, “time to exhaustion” isn‘t the same as performance. That’s something that’s routinely used in laboratory studies. But, doing something like “a time trial test” would actually measure speed and performance. But, there’s never been a head-to-head water versus coconut water-time trial—until now.
Drinking coconut water, bikers make it 10k in 971 seconds, and on plain water, about five seconds faster—in other words, no significant difference. The first study on the use of coconut water during exercise, and it looks like it’s “no more beneficial than plain water.”
How’s the coconut water industry going to spin this? They were the ones that funded the study that found no difference between plain water, coconut water, and sports drinks. So, did the authors conclude VitaCoco is no better than water? No, they said coconut water…is just as good as sports beverages! That’s finding athletes and coaches will “likely [find] of most importance”—failing to note that not only did plain water do just as well, it did better because there was twice as much stomach upset in the coconut-water groups.