Regularly eating probiotics, so-called “good bacteria” found in foods like yogurt and sauerkraut, may help your immune system work better and improve digestion. Kefir (a yogurt-like beverage) is also a good bet. Look for products labeled with a “Live & Active Cultures” seal from the National Yogurt Association, which signifies that the yogurt contains a set minimum amount of two particular types of beneficial bacteria. (While it’s not a guarantee of probiotic power—the bacterial counts don’t differentiate between added probiotic organisms and the bacteria that’s used to ferment the yogurt—the seal is a helpful start.) With the new “probiotic” cereals and granola bars on the market now, it’s not always clear how much good bacteria the manufacturers actually add to the products or whether the strains included are effective. If you really want to know about the science backing a product’s “probiotic power,” contact the manufacturer.