By now, the science is clear: The healthiest beverage you can drink is water. It’s free of sugar, salt and chemicals that can harm and age cells, as long as it’s filtered properly.

If H2O is so good for you, then boosting the hydrogen content should make it even healthier—right? That’s what more and more beverage companies are banking on. So-called “hydrogen water”—water into which hydrogen gas is dissolved—is increasingly popular. A handful of companies are now selling $3 bottles of the stuff, while others are pushing tablets that you can dissolve into your water to boost its hydrogen content. Plenty more are peddling machines that cost more than $1,000 for people who want to gas up their own home versions. That’s all for water that likely won’t taste or look any different from what comes out of the tap.

Some of these companies claim that adding more hydrogen to water increases energy, improves recovery after a workout and reduces inflammation, making regular water look like a downright underachiever.

But the science behind those claims is weak, backed only by a few encouraging studies in rats and mice and even fewer—and smaller—trials in people.

MORE: Why Your Bottled Water Contains Four Different Ingredients

Dr. Nicholas Perricone, who sells what he calls a natural antioxidant “energy recovery drink” called Dr. Perricone Hydrogen Water for about $3 a can, admits that it’s not yet known exactly how added hydrogen in water potentially works on the body. Animal studies and the few human studies that have been conducted, mostly in Japan, suggest that it may work as an antioxidant and to reduce inflammation. Oxidative stress from the sun, normal body processes and exposure to pollutants can damage cells and lead to premature aging and diseases like cancer. Inflammation also contributes to many chronic conditions, from type 2 diabetes to heart problems and brain disorders. Hydrogen appears to reduce both. That means, at least in theory, that hydrogen water could help to reduce everything from diabetes to hardening of the heart vessels to Alzheimer’s and cancer. The studies to prove whether that’s the case, however, haven’t been conducted.

Even without that confirmation, hydrogen water is the next big thing in wellness in Japan. The Ministry of Health recently approved hydrogen-infused saline IVs to help people recovering from infections and other conditions, and bathing in hydrogen water is becoming a popular spa treatment for fighting wrinkles and skin damage.

In the U.S., the hydrogen craze is mostly limited to water, and the claims are all over the map. Perricone focuses his on hydrogen’s effect on energy, which is based on his own small study of 20 people. He measured energy changes in skin cells after people drank 16 ounces of Dr. Perricone Hydrogen Water and found that people who drank it seemed to have increased activity in the enzymes responsible for producing energy in the cells.

That was enough to convince him to study hydrogen water for its ability to improve energy, which he says may affect not only muscle but the brain as well. “I don’t see any downside to drinking hydrogen water,” he says. “It’s nontoxic, it’s not expensive.” He also views it as an alternative to energy drinks.

MORE: Does Pink Himalayan Salt Have Any Health Benefits?

Still, why not? isn’t a compelling enough reason to buy a drink trumpeting health claims. For one, it’s not clear how much hydrogen is needed to have therapeutic benefits and how much water you’d have to drink to reap the potential rewards. “We don’t know anything about dosing or the frequency you need to drink hydrogen water to get health benefits,” says Robin Foroutan, a dietitian and spokesperson for the Academy of Nutrition and Dietetics. The amounts of hydrogen in the various products currently on the shelves vary widely, and there is no regulation to standardize formulas—mainly because there isn’t a solid scientific base to determine how much is needed to affect various conditions. Perricone says that the packaging for the water is also important, since hydrogen tends to dissipate very quickly and can diffuse through plastic and glass. Any products in these containers won’t likely have much added hydrogen in them, he says. (Perricone says he sells his water packed in a special aluminum coated with a proprietary compound to maintain hydrogen’s efficacy.)

“The bottom line is we are not sure, and we don’t know yet how helpful it can be for health,” says Foroutan. “It doesn’t seem like something that is risky to try. But we need more research.”

Get our Health Newsletter. Sign up to receive the latest health and science news, plus answers to wellness questions and expert tips. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Contact us at letters@time.com.