Probiotics have never had it better.

You can't even see those good-for-you microorganisms that have been found in fermented foods like yogurt, kefir, buttermilk and miso for centuries, but they are at the heart of a quickly growing industry that now includes probiotic-fortified foods such as tortillas, chocolate, hummus, granola, cereal and even pizza.

Food companies have figured out that there's a lot of money to be made selling products that, to steal a phrase from actress-turned-yogurt spokeswoman Jamie Lee Curtis, "keep you regular."

But digestive health isn't the only thing these living cultures are good for. Scientists are finding that certain strains of bacteria and yeast might help lower cholesterol and blood pressure and ease ulcers, tooth decay, vaginal infections and possibly even prevent colon cancer.

Your intestines already contain hundreds of strains

of beneficial bacteria and yeast that help keep you from getting sick and help you digest food, but the number of these cultures decreases if your diet contains a lot of sugary and/or refined foods or if you take antibiotics, which kill both good and bad bacteria.

"If you're eating a healthy diet and you have not been sick, then you don't particularly need additional probiotics," says LeAnne Skinner, a registered dietitian who owns Austin Nutrition Consultants, but people are increasingly turning to both natural and fortified sources of probiotics whether they need them or not.

The New Braunfels-based Custom Ingredients is one of many companies finding new ways to incorporate probiotics into products. Owner Jim Curry recently worked with the Austin tortilla company El Lago to create a line of probiotic tortillas, which contain bacteria that have been encapsulated and are spore-formers, which allow them to withstand the heat of cooking.

(Freezing, on the other hand, does not destroy live cultures, but some frozen yogurt makers heat the product before freezing, which would negate any beneficial effect, so check the label or ask an employee at your favorite frozen yogurt shop.)

"It can last under proper conditions for six months out of the fridge, but once it gets inside (the body), it flourishes," Curry says.

Because women make up more than 80 percent of the yogurt market, Curry says companies are looking for ways to sell probiotics to men. The technology already exists for companies to add probiotics to foods including seasoning blends, bread, ready-to-mix dips, chips and baking mixes, it's just a matter of convincing them that there is a market for the end product. "The biggest hurdle is getting companies interested," Curry says. "They get in a rut of making the same stuff over and over again."

Last year, H-E-B created a cornflake cereal with dime-sized drops of yogurt that contain lactobacillus acidophilus, one of the most common yogurt cultures. Attune sells granola and chocolate bars with a blend of three probiotics, and in 2006, a New Orleans entrepreneur opened Naked Pizza, which sells pies made with probiotic-enriched crust. (The store has franchised and will soon be opening other locations across the country, but none is currently planned for Texas.)

Some companies, including Dannon, have started developing, patenting and naming their own strains, including "bifidus regularis," the culture touted in Curtis' Activia commercials.

Many commercial yogurts, even those with extra probiotics, are sweetened with fructose and can contain more grams of sugar than protein. Some yogurt products, especially yogurt-covered bars, pretzels or raisins, are heat-treated or pasteurized, which destroys the living cultures.

As consumer awareness has grown, so has the amount of information companies provide on the labels. You can often find the specific species or strains of cultures found in the product listed on the packaging, as well as the number of colony-forming units per gram or CFU. (There are about 113 grams in one 4-ounce serving.)

The National Yogurt Association has created a voluntary Live and Active Culture seal to designate yogurts that have more than 100 million cultures per gram at the time of manufacturing (10 million for frozen yogurt), but it's hard to know for sure how many cultures are in a product by the time you eat it. Research has shown that you need to eat about a billion cultures before seeing any effect.

"There's a thousand things that can cause them to be not as active as you'd want them to be," Skinner says, including how the product is transported to and from the grocery store, how long it has sat on the shelf and the container it is stored in.