Believe it or not, sugary soda consumption in the United States has been falling for more than two decades.

Public messaging on the risks of overindulging in sugary drinks — such as weight gain, increased risk for heart disease and Type 2 diabetes — seems to have had an effect, steering people away from popular drinks such as full-sugar Coke and Sprite, experts said.

But several soft drinks designed for health-conscious consumers have entered the market. A recent ad for Poppi, a soda that describes itself as “prebiotic” and with “clean ingredients,” styles it as “revelatory” for the future of soft drinks. “This will be the last moment you ever think of soda as being a dirty word — as being bad for you,” the ad says, with an accompanying caption declaring that “in the future, everyone drinks soda.”

But is there really such a thing as a healthy soft drink?

“This is a philosophical question. Is a slightly-better-for-you product a good choice?” said Marion Nestle, who wrote a book on the soda industry and is an emeritus professor of nutrition, food studies and public health at New York University. “If you’re trying to cut down on sugar, that’s a way to do it. I guess these are better alternatives, but whether they’re good alternatives is another question.”

The global carbonated soft drinks market reached an estimated $343.4 billion this year and is expected to grow, and North America represents the largest value share, according to food industry research firm Mordor Intelligence.

Several brands, many of which advertise themselves as a low-calorie alternative with little or no added sugar, have become popular. They include Olipop — which is on track to hit $500 million in sales this year, according to Bloomberg — Zevia, Whole Earth, Culture Pop, Live Soda, Sidekick and Green Cola.

But when it comes to health, most soft drinks — even those with fewer calories — are not the best choice, experts said.

“In my field, there’s a phrase: ‘health halo,’ which is where you try to make something that’s not all that healthy look healthy. And I would say that’s the case with these products,” said Marlene Schwartz, director of the University of Connecticut’s Rudd Center for Food Policy and Health.

Companies are able to use unregulated descriptors such as “clean,” “green” and “gut healthy,” and many use appealing labels such as “naturally sweetened,” “made with live probiotics,” “non-GMO” and “all-natural flavoring.” Several of these claims are not based on vigorous research, and it’s usually unclear whether these products have enough of any particular “healthy” ingredient to truly yield a positive effect, Nestle and Schwartz said.

Last month, a consumer filed a class-action lawsuit against Poppi, alleging that the brand contained too little of any prebiotic ingredient to have its advertised effects. Poppi did not respond to a request for comment but said in a statement to the Associated Press around the time of the lawsuit that it stands by its products and called the lawsuit “baseless.”

Olipop, one of the new soda brands, says its line of products “supports digestive health” and lists what it calls “OliSmart” ingredients such as calendula flower, nopal cactus, kudzu root and marshmallow root. The company says in its marketing that its products contain prebiotics, botanicals and plant fiber, and that some of its flavors promote immune system health.

Nestle said she “doesn’t see anything in the ingredients list” of Olipop beverages that is going to benefit “the microbiome, digestive function or metabolic health.” It’s also not clear how much of each ingredient is in any given can.

Olipop CEO Ben Goodwin said in an email that Olipop’s formulas are research-backed and that the amount of fiber in its products — up to 9 grams per can depending on the flavor — meets the Food and Drug Administration’s requirements for an “excellent source of fiber.” He said the brand invests significant resources in research and development, including human clinical trials studying the product’s impact on metabolic health and other health measures.

In addition to obesity, Type 2 diabetes and heart disease, tooth decay, gout, arthritis, nonalcoholic fatty liver disease and kidney diseases have been linked to frequent consumption of sugar-sweetened beverages, according to the Centers for Disease Control and Prevention.

Federal dietary guidelines recommend that U.S. adults consume no more than 10 percent of their daily calories from sugar, and the American Heart Association suggests no more than 25 grams per day for women and 36 grams for men.

A 12-ounce can of Olipop has 2 to 5 grams of sugar, compared with about 39 grams in a 12-ounce can of Coke. Some newer soda brands marketed as healthy have zero grams of sugar, largely because of the use of artificial sweeteners or sugar substitutes such as stevia.

And it’s still “hard to know” whether even a Coca‑Cola Zero Sugar or Pepsi Zero Sugar is a significantly healthier choice than a full-sugar can, Nestle said.

For those looking for a sweet, bubbly drink, both Schwartz and Nestle said that making one at home might be the best bet.