Terms such as "L. casei immunitas" and "probiotics" that, not that long ago, would have mystified most U.S. consumers are rapidly becoming a part of many shoppers' vocabularies, thanks to growing recognition of the importance of digestive health.

But according to a new report from London-based Datamonitor, the success of "gut-friendly" yogurt products such as Activia and Yakult represents just the beginning of a digestive health movement in this country, where the number of people who suffer from digestive complaints such as heartburn and irritable bowel syndrome is expected to rise to almost 73 million — almost a quarter of the population — by 2013.

According to the report, most U.S. consumers already trust the efficacy of products that contain both probiotics or their lesser-known cousin prebiotics, with only a minority of U.S. consumers (14.4 percent) reporting they don't believe the digestive health claims made by such foods.

Manufacturers are responding by incorporating probiotics into more foods that people eat every day, including desserts such as ice cream — and even ketchup, the report said. What's more, it continued, prebiotics also  are finding their way into various products, including breakfast cereals.

"It's this ease of consumption that is making digestive health regimens so appealing," the report said, calling "daily dosing" the key to success.

However, it continued, "The digestive health industry faces a tough challenge justifying prices at a time when consumers are looking to save pennies." Still, it noted, "The future of foods and beverages that claim to improve digestive health is looking good."

Datamonitor Consumer Markets Analyst Mark Whalley concluded, "People find these products appealing and, more importantly, they like how they taste. Digestive health has strong links with immunity health, which means that consumers feel better after eating their probiotic yogurts. This is what keeps them coming back for more."

For more information about the report, go to www.datamonitor.com.