Lactobacillusacidophilus (L. acidophilus) is the most commonly used probiotic, or "friendly" bacteria. Many healthy bacteria live in the intestines and vagina, where they protect against "bad" bacteria that can cause disease. They do this is a couple of ways: for example, when L. acidophilus breaks down food in the intestine, several substances are formed (such as lactic acid and hydrogen peroxide) that create an unfriendly environment for “bad” bacteria. Probiotics are often suggested as a supplement when you take antibiotics. Antibiotics kill bacteria, but don’t discriminate between “friendly” and “unfriendly” organisms, so the balance between good and bad bacteria in the intestines can be upset. It is thought that taking probiotics helps restore the healthy balance of bacteria.

Other probiotics include several Lactobacillus species (spp.), such as L. bulgaricus, L. casei, and L. reuteri, Lactobacillus GG,Bifidobacterium longum, Bifidobacterium bifidum, Streptococcus thermophilus, and Saccharaomyces boulardii (a kind of yeast).

In addition to probiotics, some health care providers suggest taking “prebiotics.” These are the soluble fiber found in some foods or supplements that help prebiotics thrive in the intestine. Examples include fructooligosaccharides (FOS), the carbohydrates found in fruit.

Probiotics may be used for the following:

Vaginal infections

Several clinical studies suggest that using L. acidophilus vaginal suppositories can help treat bacterial vaginosis. A small number of clinical studies suggests that eating yogurt with L. acidophilus cultures may also help. Some people also use L. acidophilus to treat or prevent vaginal yeast infections, although the evidence about whether it is effective is mixed. Additional clinical research is needed.

Diarrhea prevention

The evidence for using Lactobacillus to prevent diarrhea is mixed. Some clinical research suggests Lactobacillus acidophilus may be effective when used to prevent traveler’s diarrhea (caused by eating contaminated food). Other studies have found that Lactoabcillus GG was effective. A mix of probiotics (Saccharomyces boulardii and a mixture of Lactobacillus acidophilus and Bifidobacterium bifidum) helped people with treat traveler’s diarrhea in one study.

Probiotics, especially Lactobacillus GG, may help prevent or treat infectious diarrhea in children and adults, although the evidence is mixed. Studies seem to show probiotics are most effective in treating rotavirus in children. Diarrhea in children can be serious, and you should call your doctor if it lasts more than a day or your child seems dehydrated.

Other studies have found that probiotics, taken regularly, may help prevent gastrointestinal infections in adults.

Several studies -- though not all -- suggest that probiotics, especially Lactobacillus GG and S. boulardi, may help prevent diarrhea associated with taking antibiotics. Antibiotic-related diarrhea can be serious, so you should tell your doctor about it.

Other uses

Lactobacillus and other probiotics have been suggested for a number of conditions, although evidence in most cases is preliminary or mixed:

• Replacing the "friendly" intestinal bacteria destroyed by antibiotics
• Helping digestion and suppressing disease-causing bacteria
• Treating chronic constipation
• Treating symptoms of irritable bowel syndrome and inflammatory bowel disease (such as Crohn's disease and ulcerative colitis)
• Improving lactose tolerance in people who are lactose intolerant
• Enhancing the immune system. Studies have suggested that consuming yogurt or milk that contains specific strains of Lactobacillus or taking supplements with Lactobacillus or Bifidobacterium may improve the body’s natural immune response.
• Lowering risk of pollen allergies
• Reducing the risk of childhood eczema
• Helping to treat high cholesterol

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
• Yogurt enhanced with probiotics

L. acidophilus supplements should be refrigerated for best quality. Some preparations are in a form that does not break down under normal temperatures and may be convenient for travelers who can’t refrigerate their supplements. Check the package label for storage instructions.

Prebiotics occur naturally in foods, but supplements provide a more concentrated source. Prebiotics are oligosaccharides -- chains of sugar units linked together -- and include inulin and fructooligosaccharides (FOS). Fructoligosaccarhides (FOS) are the most commonly used.

Pediatric

Newborns and Infants (0 - 1 year): Always check with your pediatrician before giving dietary supplements to an infant or child. 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. Make sure you use products specifically formulated for infants.

Add ¼ tsp or ¼ capsule to water for the treatment of mouth infections.

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 lists guidelines for the most common uses:

For prevention or treatment of diarrhea: Take 1 -2 billion colony-forming units or CFUs per day. Some health care providers may recommend up to 10 - 15 billion cells per day.

For vaginal infections: Lactobacillus capsules or tablets may be inserted directly into the vagina. Orally, eat 8 ounces of yogurt (with live active cultures containing one of the Lactobacillus or Bifidobacterium strains listed above) daily or take a daily supplement containing at least 1 - 2 billion live organisms.

For maintaining intestinal health: Take 1 - 15 billion CFUs daily. If for prevention of antibiotic related diarrhea, some health care providers recommend taking it 2 - 3 hours after the antibiotic.

If diarrhea occurs, decrease the dosage or stop taking the product and talk with your health care provider.

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

Lactobacillus acidophilus is generally considered safe for most people. Gas, upset stomach, and diarrhea are potential side effects in some people (not on antibiotic therapy) who take more than 1 - 2 billion L. acidophilus cells daily.

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.

People with weakened immune systems (such as those receiving chemotherapy or drugs that suppress their immune systems) should ask their doctor before taking probiotics.

People with artificial heart valves should not take L. acidophilus because of the rare chance of bacterial infection.

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 health care provider.

Sulfasalazine -- A laboratory study suggests that L. acidophilus speeds up metabolism of sulfasalazine, a medication used to treat ulcerative colitis.

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