Once only available in health food stores or ethnic markets, coconut water has gone mainstream, with new brands and varieties popping up regularly. And for good reason -- it's high in beneficial electrolytes, like potassium and magnesium. Drinking a serving or two of coconut water daily is not likely to be dangerous -- unless, of course, you're allergic -- but you should still be mindful of your calorie, sugar and sodium consumption. Drinking large amounts of coconut water after profuse sweating, however, can cause a dangerous electrolyte imbalance, so it's best to chat with a registered dietitian or doctor to stay safe.
Unflavored coconut water is relatively low in calories at 46 per cup. But bottled or packaged coconut water often contains more than 1 cup of fluid, so you could be taking in a few cups of coconut water a day. That can add up. An extra 92 calories daily -- the equivalent of 2 cups of plain coconut water -- translates to over 33,000 extra calories over a year, or the equivalent of 9.5 pounds of fat. Flavored coconut water is higher in calories -- one commercial variety of latte-flavored coconut water contains 120 calories per serving. If you're drinking lots of coconut water, make sure you fit all those extra calories into your daily calorie "budget," or you'll pack on the pounds.
Coconut water also serves as a source of sodium. That makes it good for replenishing sodium lost during a workout but not so great if you're drinking lots of coconut water throughout the day. A cup of plain coconut water contains 252 milligrams of sodium, roughly 17 percent of your daily adequate intake. Drink two 16-ounce bottles of coconut water, and you'll take in almost 70 percent of your daily intake, which makes it likely you'll exceed your daily sodium limit. Regularly taking in too much sodium ups your risk of high blood pressure and stomach cancer. Check for lower-sodium varieties, and make low-sodium foods -- like unprocessed grains, fruits and veggies -- the foundation of your diet.
Plain coconut water is only subtly sweet, so some companies punch up the flavor by adding juice or sugar. That adds to the calorie content, and if you're drinking flavored coconut water daily, it significantly adds to your sugar intake. A commercially available latte-flavored coconut water, for instance, contains 23 grams of sugar per serving -- more than a serving of chocolate ice cream. Sugar-sweetened beverages aren't as filling as real food, explains the Harvard School of Public Health, and they contribute to obesity. Stick to plain coconut water -- it has just 6 grams of sugar per cup -- to keep your sugar intake low.
Electrolyte Imbalance Dangers
Surprisingly, the potassium that makes coconut water beneficial under normal circumstances can prove fatal when consumed in excess. One man, who had spent the day playing tennis outdoors in 90-degree-Fahrenheit weather, developed excessively high potassium levels -- a condition called hyperkalemia -- after drinking 88 ounces of coconut water, reports an article published in "Circulation: Arrhythmia and Electrophysiology" in 2014. Hyperkalemia causes lightheadedness, weakness and loss of consciousness. If you're using coconut water as a post-workout supplement to help with rehydration, check with a medical professional to ensure you're using it safely.