Acidophilis, known scientifically as lactobacillus acidophilus, is one of the most commonly used probiotic bacteria. In common usage however, the word acidophilus is used to refer to any of a group of probiotics, which includes lactobacillus acidophilus and several other beneficial bacteria as well.
Probiotics are basically good bacteria - some of them occur naturally in the body, while others exist in certain foods. In the last few decades, many food manufacturers have been adding probiotic supplements to their products due to the benefits that they are supposed to provide. These include prevention of many diseases and infections of the digestive tract, controlling cholesterol and blood pressure, and stopping harmful bacteria from growing in the body. Probiotics are often recommended after a course of strong antibiotics, because the antibiotics kill of the good bacteria that naturally grow in the body, making place for harmful bacteria and fungi. Probiotics such as acidophilus are thought to take the place of the body's natural bacteria, thus blocking harmful microbes from moving in.
Acidophilus and other probiotics are available as supplements and in many food products today, so if you are interested in trying them, you should simply look for products marked as "probiotic". Although there is as yet not enough proof for all the supposed benefits of probiotics, there is evidence that they have at least some benefit, and they are completely safe.
answered by M W