The best known of all "friendly bacteria", acidophilus is a probiotic which is found naturally in the human digestive system, where it helps to maintain good digestive health.
Acidophilus plays a particularly important role in the digestion of dairy products, breaking them down into lactic acid and hydrogen peroxide. Acidophilus and other probiotics alter the pH balance of the intestines, making them more acidic, and thus hostile to the more harmful types of bacteria which can cause stomach upsets and digestive issues.
As well as helping to maintain a healthy digestive system, acidophilus is also present in the vagina and cervix, and helps to protect against yeast infections. It is known that probiotics taken after a course of antibiotics can help to restore the proper balance of bacteria in the intestines following illness. It's also thought that probiotics may help to treat eczema.
Acidophilus is found in live cultured yoghurt, and in fermented foods such as kimchi, sauerkraut, kefir and miso.
As a supplement, you can take acidophilus in capsule form or as chewable tablets. Some supplements encase the probiotics in triple layered shells in order to ensure that they survive the ingestion process and reach the intestines intact.