You’ve just finished a butt-blasting boot-camp workout. Drenched with sweat, you ponder your rehydration options.

Should you opt for a sports drink, plain water — or a beverage that’s been around for thousands of years but has only gained market traction in the U.S. in the last few years, coconut water?

Nearly every convenience store in the U.S. sells at least one brand of coconut water, with soft-drink giants Coca-Cola and Pepsi each investing in a different label of coconut water, which is essentially the liquid extracted from a hacked, young coconut (and different from coconut milk, which is the pressed white "meat" inside the shell).

But is coconut water healthy? And is there any difference between shimmying up a tree, plucking a coconut and hacking it open with a machete and drinking its sweet juice versus doing so from a packaged box?

Coconut nutrition facts
One cup of natural coconut water (unpackaged) contains 45 calories, a very small amount of fat, no cholesterol, and most importantly, for rehydration purposes:

  • 9 grams of carbohydrate
  • 6 grams of sugar
  • 15 percent of the daily value (DV) for magnesium
  • 17 percent DV potassium (more than a banana in a single serving)
  • 10 percent DV sodium
  • 6 percent DV calcium (also an electrolyte like magnesium, potassium and sodium)
Natural coconut water also contains other important minerals and vitamins, such as 10 percent DV of vitamin C. A big health bonus for natural coconut water: it contains 3 grams of dietary fiber (over 10 percent DV).

Packaged coconut water: The next best thing?
Have time to stop at the grocery store after work before you hit the gym to pick up some coconuts and hack them open with a machete after your workout? Didn’t think so.

Most Americans who drink coconut water will do so out of a box or bottle. Is this as healthy as all-natural coconut water? According to one popular brand’s website, the most glaring difference between natural and branded coconut water is the lack of fiber in the packaged bottles.

There’s also more sugar — twice as many grams — in packaged coconut water; not necessarily a bad thing if you’re working out and sweating profusely most days of the week, but for your average American, the relatively high sugar content (water, of course, has none) may outweigh any of the other rehydration benefits that packaged coconut water offers.

Rehydration effectiveness
Medical studies on the efficacy of coconut water are hard to find, but there are a couple, albeit very small ones.

A study in the Southeast Asian Journal of Tropical Medicine and Public Health compared and assessed the rehydration effectiveness of plain water, sports drinks, fresh young coconut water and sodium-enriched fresh young coconut water (SCW). The results: ingesting SCW was as good as ingesting a commercial sports drink for whole body rehydration after exercise-induced dehydration.

Can coconut water reduce stress?
According to one study in the West Indian Medical Journal, the data suggests yes. Twenty-eight subjects with hypertension were given bottled water, or coconut water, or another tropical drink called mauby, or a mixture of coconut water and mauby. The group drinking only coconut water had the biggest drop in blood pressure.

Although no medical professional would praise the medicinal merits of coconut water with such little clinical cache, traditional communities have been using coconut water (and of course, the whole coconut) for dozens of conditions from dandruff to diabetes.

Is rehydrating with coconut water necessary?
With most sport-drink bottles containing dozens of grams of sugar, it would seem that coconut water would be a better option for a carb-conscious, high-intensity athlete.

And for your average American, save yourself the $2-3 a pop on packaged coconut water; plain water and a diet rich in fruits and vegetables should keep you adequately hydrated and healthy.

But  what do the medical folks say?

"Coconut water has high levels of potassium, so it helps balance electrolytes in the body," says Dr. Jennifer Landa, BodyLogicMD's chief medical officer. "Most of us have a higher intake of sodium than potassium, so coconut water aids in hydration. This is especially important after heavy exertion and moderate endurance training. One caveat is the sweeteners that are often times added to coconut water to make it more palatable. Try to find coconut water that is unsweetened. It tastes delicious just as it is anyway!"

"Coconut water, as long as it has no added sugar, is an excellent way to rehydrate," says Dr. Jacob Teitelbaum, medical director of the national Fibromyalgia and Fatigue Centers. "It is low in sugar, and very high in potassium, with an 8-ounce serving having about 500 milligrams. Low potassium is a major cause of low blood pressure, tight muscles and abnormal heart rhythms — and you can't get adequate amounts in a multivitamin." 

What do you think about coconut water? Let us know in the comments below.

Judd Handler is a health writer based in Encinitas, Calif.