You’ve probably heard that probiotics—the active cultures in some yogurts, for example—are good for your health. But not all probiotics are created equal. Here’s what you need to know to boost immunity, soothe itchy skin, quell an upset stomach, and more.
Lab studies show that many probiotics have invigorating effects on the immune system. In theory, this should increase a persons resistance to disease. But only a few strains, like L. casei DN-114001, L. rhamnosus GG, and L. acidophilus NCFM, seem to reduce the frequency and severity of illnesses like winter colds. In a study with 360 people over age 60, daily use of L. casei DN-114001 cut the duration of respiratory infections by a one and a half days and the severity by 20%. Similarly, in a study with 571 kids in day care, L. rhamnosus GG reduced both stay-at-home sick days and the number of infections serious enough to require antibiotics. And in a winter study of more than 200 preschoolers, the third strain (L. acidophilus NCFM) reduced the incidence of fever by 48%, cough by 42%, and antibiotic use by 68%. Researchers think similar benefits may be enjoyed by all age groups.
Scientists link a modern epidemic of allergic conditions with the relative lack of bacteria in our sanitized lives. And some research shows that certain probiotics raise levels of allergy-calming chemicals in the blood. But probiotics dont appear to be all that helpful—with one exception: eczema, an allergic skin condition. Daily doses of L. rhamnosus HN001 or L. rhamnosus GG mixed into breast milk or formula substantially reduced the risk that children would develop eczema (but not other allergic conditions such as hay fever, asthma, or food allergies).