"In general, we have no evidence that water can be improved," says Prevention magazine's nutrition adviser David Katz, MD, MPH, an associate professor adjunct in public health at Yale University's School of Medicine. "There is no convincing evidence of benefit from any version of 'enhanced' water."
In general, he says, "we consider a beverage 'water' if it has no calories, no sodium—or trivial amounts in mineral water—and no sweetener—sugar, alternative, or artificial. If a product is sweetened, it's not water—it's a soda."
Here's what you need to know before you glug your next jug of fancy water. (Use our formula to figure out just How Much Water You Really Need.)
More: Hydration Basics
1. Coconut Water
Dubbed "mother nature's sport drink," coconut water's high levels of potassium, sodium, and antioxidants make it seem like the ultimate post-sweat swig.
But just last year, scientists at ConsumerLab.com took several brands of coconut water to the lab and tested them to be sure. Their findings? Only one brand actually contained the amount of sodium and potassium claimed on its nutritional label.
Assuming the label is telling the truth, coconut water is a decent choice for after a light workout, but it's not a good call after intense ones because it doesn't contain enough sodium, according to a recent study presented at the 244th National Meeting & Exposition of the American Chemical Society.
2. Waters Enhanced With VitaminsSure, some of these beverages have vitamins in them, but with up to 200 calories and 33 g of sugar per bottle, you're better off thinking of these drinks as soda.
What's more, says Ara DerMarderosian, PhD, a pharmacognosy professor at the University of the Sciences in Philadelphia, waters that are heavily fortified with vitamins and minerals may actually suppress your immune system if you're already taking in enough vitamins and minerals through your diet.
If you want a little zing in your water, try Ayala's Hint, Metromint or Wateroos. Each bottle is free of sugar, sweeteners, preservatives, and calories.
More: Liquids With Calories
3. Electrolyte Water
Smart Water is distilled—which means it's boiled and then recondensed from the steam to kill microbes and remove minerals—and enhanced with potassium, magnesium and calcium.
According to the company's website, it also"one-ups ma nature by adding in electrolytes for faster hydration."But there's no real evidence of there being a benefit to adding electrolytes to a hydration formula, says Dr. Katz, unless you're intensely exerting yourself in blazing heat and eating isn't an option. "Under other circumstances, water in its native state will do just fine."
4. Sleep-Inducing WaterDream Water infuses its drink with three natural sleep ingredients: GABA (to help relax), melatonin (to help induce sleep) and 5-HTP (to help improve the quality of sleep). The brand claims to be "the first all-natural sleep enhancer with zero calories, no preservatives and natural active ingredients that helps you relax and fall asleep," and it's available in three flavors—Snoozeberry, Lullaby Lemon, and Pineapple PM.
Should you drink the stuff?
"It's intended to help with relaxation and sleep, and does contain ingredients that might support this, which makes it really a 'tonic' or 'functional' drink," says Dr. Katz.
In other words, it's more herbal supplement than it is water. As for whether it actually helps with sleep, well, the jury's still out on that one, but anyone who's chugged liquid before bed knows how that can go.
5. OWaterEach option available from OWater—sweetened, unsweetened and sport—is advertised as gluten-free. Since gluten is a protein found in grains like wheat, we hardly think this is something worth touting on the label. If that doesn't raise a red flag, this might: Their plain version is sweetened with sugar, and they fuse their H2O with electrolytes&emdash;an ingredient Dr. Katz says isn't necessary when working out.
The good news: these 3 Delicious Ways to Hydrate offers fun recipes that use real fruit, like grapes, strawberries and blueberries to help you meet your water needs—naturally.