Lactobacillus acidophilus (L. acidophilus) is the most commonly used probiotic, or "friendly" bacteria. Such healthy bacteria inhabit the intestines and vagina and protect against the entrance and proliferation of "bad" organisms that can cause disease. This is accomplished through a variety of mechanisms. For example, the breakdown of food by L. acidophilus leads to production of lactic acid, hydrogen peroxide, and other byproducts that make the environment hostile for undesired organisms. L. acidophilus also produces lactase, the enzyme that breaks down milk sugar (lactose) into simple sugars. People who are lactose intolerant do not produce this enzyme. For this reason, L. acidophilus supplements may be beneficial for these individuals.

Other potential probiotics include a variety of Lactobacillus species (spp.), such as the caseiGG, rhamnosus, NCFM, DDS-1, and johnsonii strains, Bifidobacterium longum, Bifidobacterium bifidum, Streptococcus thermophilus, Enterococcus faecium, Saccharaomyces boulardii, Bacillus spp., and Escherichia coli.

Prebiotics refers to the soluble fiber component found in certain foods or supplements that stimulate the growth of probiotics in the gastrointestinal tract.

Probiotics offer a variety of potential therapeutic uses. These include the following:

• Replacing the "friendly" intestinal bacteria destroyed by antibiotics.
• Aiding digestion and suppressing disease-causing bacteria.
• Preventing and treating diarrhea, including infectious diarrhea, particularly from rotavirus (a virus that commonly causes diarrhea in children).
• Treating overgrowth of "bad" organisms in the gastrointestinal tract (a condition that tends to cause diarrhea and may occur from use of antibiotics).
• Alleviating symptoms of irritable bowel syndrome and, possibly, inflammatory bowel disease (such as Crohn's disease and ulcerative colitis).
• Preventing and/or reducing the recurrence of vaginal yeast infections, urinary tract infections, and cystitis (bladder inflammation). The best scientific evidence exists for vaginal infections.
• Improving lactose absorption digestion in people who are lactose intolerant
• Enhancing the immune response. Studies have suggested that consumption of yogurt or milk that contains specific strains of Lactobacillus or supplements with Lactobacillus or Bifidobacterium may improve the natural immune response. Further research is needed to confirm these early findings and to best understand how the improved immune function may or may not help in warding off infections.
• Aiding the treatment of respiratory infections such as sinusitis, bronchitis, and pneumonia. More research is needed in this area.
• Lowering risk of allergies. Examples include asthma, hay fever, food allergies to milk, and skin reactions such as eczema.
• Helping to treat high cholesterol. More research is needed.
• Reducing the risk of recurring bladder tumors once this cancer has been treated. Much more research is needed in this area.
• Other conditions under investigation for use of probiotics include colon cancer, HIV related diarrhea, and Helicobacter pylori, an organism that can lead to development of ulcers.

The primary dietary sources of L. acidophilus include milk enriched with acidophilus, yogurt containing live L. acidophilus cultures, miso, and tempeh.

Prebiotics are found in breast milk, onions, tomatoes, bananas, honey, barley, garlic and wheat.

L. acidophilus preparations consist of dried or liquid cultures of living bacteria. These cultures are usually grown in milk but can sometimes be grown in milk-free cultures. L. acidophilus is available in the following forms:

• Freeze-dried granules
• Freeze-dried powders
• Freeze-dried capsules
• Liquid L. acidophilus preparations (which must be kept refrigerated)

Prebiotics occur naturally in foods, but supplements provide a more concentrated source of this substance. Prebiotics are oligosacchrides, chains of sugar units linked together. Inulin is a long-chain oligosacchride (from 2-60 sugars) and fructooligosaccharides (FOS) are short-chain oligosaccharides (from 2-7 sugars). It is not clear at this time which type of prebiotic is most effective.

Pediatric

Newborns and Infants (0 to 1 year)

• Liquid preparations may be used as a lotion and applied topically to diaper area for yeast infections and diaper rashes.
• If the child is on antibiotic therapy, ¼ tsp or ¼ capsule can be taken orally 2 hours after each dose of antibiotics to replace beneficial bacteria.
• Add ¼ tsp or ¼ capsule to water for the treatment of oral infections.

Children (1 to 12 years)

• Refer to recommended dosage on product label

Adult

Recommended doses of L. acidophilus vary depending on the health condition being treated. Check the specific dosage recommendations on the product label. The following list provides guidelines for the most common uses:

• Prevention or treatment of diarrhea: 1 to 2 billion viable cells per day (some experts may recommend up to ten billion cells per day)
• Vaginal infections: 8 ounces of yogurt (with live active cultures containing one of the Lactobacillus or Bifidobacterium strains listed above) daily or an oral daily supplement containing at least 1 to 2 billion live organisms. Clinical experience also suggests that placing yogurt with live acidophilus cultures directly to the vaginal area, using a disposable spatula and wearing a sanitary pad, helps to relieve itching and inflammation. Similarly, lactobacillus capsules or tablets may be inserted directly into the vagina.
• Cystitis: 1 to 2 capsules or tablets inserted into the vagina nightly for two weeks
• Maintaining normal intestinal flora: 1 to 10 billion viable cells per day

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable healthcare provider.

Mild gastrointestinal upset may occur in some individuals (not on antibiotic therapy) who take more than 1 to 2 billion L. acidophilus cells per day.

There has been one report of anaphylaxis (a serious allergic reaction accompanied by shortness of breath and loss of consciousness) in a person taking inulin, a type of prebiotic.

If you are currently being treated with any of the following medications, you should not use Lactobacillus or other probiotics without first talking to your healthcare provider.

Sulfasalazine
A laboratory study suggests that L. acidophilus speeds up metabolism of sulfasalazine, a medication used to treat ulcerative colitis. The significance of this information is unknown at this time.

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