Probiotics do more than help digestion. These helpful bacteria also may ward off a cold, treat high cholesterol, ease anxiety and alleviate allergies.

Probiotics must be taken for about five straight days to build up to a useful level—and then should continue to be consumed regularly. They alter gastrointestinal balance in ways that can fight diarrhea and constipation…prevent the release of toxins by harmful bacteria…and improve the strength of the gastrointestinal barrier that allows nutrients through and repels pathogens.

Probiotics have few side effects—although people with digestive disorders should talk with a doctor before taking them.