1.     Probiotics are microbes that can do good things inside your body. Certain bacteria and fungi can help our bodies fight disease and work more efficiently. In fact, we already have a lot of these helpful microbes—known as probiotics—inside our digestive tracts. But many people add more by consuming probiotic supplements designed to combat specific ailments.

2.     For such small creatures, probiotics have grown very big. While a few proponents have been arguing their benefits for decades, probiotics were virtually nonexistent in the mass market 20 years ago. That began to change with the introduction of products such as Dannon Activia, a probiotic-enhanced yogurt. Aided to some extent by Dannon’s aggressive marketing efforts, public awareness of probiotics has risen from 9 percent in 2001 to 31 percent last year. Now consumption is skyrocketing, and in 2007 alone, 750 new probiotics products were launched in the United States.

3.     These things just might work. In the past, academic researchers, including myself, were highly skeptical of the health claims made about probiotics products. The research was so poorly designed and executed that it made proponents look like snake oil salesmen. However, in recent years, the body of evidence has grown more and more compelling, and many well-constructed studies now have shown health benefits from specific bacterial strains at specific doses.

4.     The key is getting the right microbe—in the right amount. Different microbial strains do different things, and if you don’t have exactly the right one for your needs, you may be wasting money. For example, the bacterium Lactobacillus rhamnosus can mitigate diarrhea after a course of antibiotics, but only if a patient consumes 10 billion to 20 billion cells of the LGG strain per day over a period of 10 to 14 days.

5.     Buyer beware: Labels on probiotics products aren’t uniformly helpful. Many product labels are incomplete, omitting key information about strains and doses. Some labels even make misleading health claims. Before starting a regimen of probiotics, it’s a good idea to do some extra research. Look online or contact the manufacturer to gather all the data.

James Steele, a CALS professor of food science, studies the bacteria that influence Cheddar cheese flavor. A few years ago, he expanded his research program to include the mechanisms by which probiotics influence human health.