Probiotics are living microorganisms, usually lactic acid bacteria, that when consumed in sufficient numbers can provide health benefits that go beyond basic nutrition. The benefits are due, in large part, to the effects of these so-called "friendly" bacteria on different intestinal functions. Daily consumption of probiotic foods, such as yogurt and cultured dairy drinks, may be beneficial in one of several ways. Some probiotics help strengthen your body's natural defenses by providing a regular source of "friendly" bacteria for the intestinal tract, some might provide a nutrient-rich source of calcium for people who are lactose-intolerant; and some may help correct an imbalance of good to bad bacteria in the intestinal tract. Several different types of probiotic cultures (L. casei, L. acidophilus, L. plantarum, B. bifidum) are used in many dairy products around the world. Potential benefits may vary depending on the type of probiotic bacteria consumed.