By pitching its yogurt as a single-serving fix for intestinal irregularity, Dannon created a top-selling global probiotics brand in Activia. And because of this false health promise—it actually takes three servings to yield results—the company had to fork over $21 million in December 2010 to settle Federal Trade Commission charges of using improper health claims on the product. This is just one example of the threats facing the digestive health products market’s well-being.

Last year, U.S. shoppers bought $1.2 billion worth of gut health supplements—9 percent more than in 2009, according to Nutrition Business Journal. These growth statistics make the category look like the picture of health—at least on a spreadsheet. Not even a 2009 ConsumerLab report revealing that several probiotics didn’t contain the colony-forming units guaranteed on their labels hindered sales of this marquee player among digestive health supplements.

“There’s growing consumer interest in and responsiveness to the notion that common health concerns, such as gas, bloating, fatigue, headaches, indigestion, constipation and diarrhea, are manageable with fiber, enzymes and probiotics,” says John Kenny, product educator for Super Supplements, a Seattle-based retail chain.

Still, experts say that weak scientific support for certain products, along with consumer confusion about the multiple benefits and origins of key digestive health ingredients, could eventually take their toll on sales growth—unless manufacturers and retailers get gutsy in how they support and market the gut health category.

To help you keep your store’s digestive products sales flowing, here’s an in-depth look at the key challenges, compelling innovations and novel products within the top three gut health supplements categories: probiotics, enzymes, and fiber and laxatives.