Guide To Lactobacillus Acidophilus

Bacteria of the species Lactobacillus Acidophilus are normally found in the mouth, the gastrointestinal tract and the vagina. This species is among the most important of the beneficial bacterial species and is one of the most common probiotic species available in commercial supplements. Studies suggest it may provide benefits to people suffering from a variety of health problems including vaginal infections, antibiotic-associated diarrhea, lactose intolerance, allergies, various digestive disorders and many other conditions.

Lactobacillus Acidophilus

While people generally think of bacteria as harmful, some species of bacteria, including Lactobacillus acidophilus, actually help keep people healthy. They do this by preventing the overgrowth of those bacterial species that cause health problems or by producing substances that help with digestion, immune function or other critical processes. Although these helpful bacteria are naturally present in the body, certain conditions and medications cause them to die in large numbers. This die off can produce further health problems, so researchers and doctors have begun to look into foods and supplements that restore or encourage a healthy population of beneficial bacteria in the body and to study the benefits of maintaining or increasing normal levels of healthy bacteria.

Potential Uses of L. acidophilus

Use of L. acidophilus may be helpful for treating and preventing a variety of diseases and disorders, but more research is needed to establish definitive links and dosing regimens. Some specific uses of this probiotic that are supported by existing research include those discussed below.

  • Preventing Antibiotic-Associated Diarrhea – Antibiotics kill bacteria or stop these microorganisms from reproducing. Unfortunately, most antibiotics destroy both harmful and helpful bacteria. The loss of the helpful bacteria that normally colonize the gut may result in diarrhea, gas and other unpleasant antibiotic side effects. For this reason, many researchers recommend using probiotics, like L. acidophilus, along with antibiotics to minimize side effects. This recommendation is supported by a number of published studies.
  • Treating and Preventing Vaginal Infections – Good evidence supports the use of L. acidophilus to treat or prevent a variety of vaginal infections. Probiotics containing members of the species are also often recommended to prevent the development of yeast infections in women taking antibiotics. This is because the use of antibiotics results in the loss of beneficial bacteria in the vagina, and supplements help to replenish the body’s population of healthy bacteria.
  • Helping to Relieve Symptoms of Irritable Bowel Syndrome (IBS) and Other Gastrointestinal Disorders – Probiotic supplements containing L. acidophilus can help reduce or prevent inflammation in the intestinal tract and help treat IBS and other inflammatory diseases of the intestines. These supplements, however, only work in mild to moderate cases and do not appear to provide significant benefit to those who are seriously ill.
  • Treating Lactose Intolerance – Members of the species L. acidophilus may be able to help intolerant patients digest milk and other dairy products because these bacteria can directly digest lactose, which is a sugar found in dairy products, or produce compounds that help to break this sugar down into its parts. More research, however, is needed to demonstrate the efficacy of L. acidophilus supplements for this purpose.
  • Helping to Alleviate or Prevent Various Allergic Diseases – Some evidence suggests that use of L. acidophilus in the young can help prevent allergic diseases later in life by influencing the development of the immune system. In addition, animal studies indicate that L. acidophilus reduces allergic responses, and other studies suggest that milk containing these bacteria may help relieve the symptoms of hay fever.

Other Potential Uses

Some evidence suggests that L. acidophilus may also help treat or prevent the following conditions when used alone or in combination with other medications:

  • Anemia
  • Insulin sensitivity in people with type 2 diabetes
  • Keratoconjunctivitis sicca
  • Eczema in children
  • Flu
  • Liver disease
  • Necrotizing enterocolitis
  • Pneumonia
  • Pouchitis
  • Preterm delivery
  • Sepsis in newborns

Dietary Sources of Lactobacillus  Acidophilus

  • Milk enriched with L. acidophilus
  • Yogurt with live L. acidophilus cultures
  • Miso
  • Tempeh

It is also available alone or paired with other beneficial bacteria or prebiotics, which are sources of soluble fiber that feed beneficial bacteria in the intestines, in a variety of supplements and medications. These include granules, powders, capsules, liquid preparations, tablets, eye drops, injectable vaccines and vaginal suppositories.


You should always follow your doctor’s advice and refer to specific label instructions when taking probiotics. In general, experts recommend that healthy adults take 1 to 20 billion colony forming units per day to treat and prevent diarrhea or to maintain intestinal health. In addition, when you are taking an L. acidophilus supplement with an antibiotic, most doctors recommend taking the supplement and the antibiotic at least two to three hours apart since antibiotics can kill L. acidophilus.


L. acidophilus products contain live bacterial cultures. This means that to remain effective, the bacteria in these products need to remain alive. To keep the bacteria alive, be sure to store all products according to package directions. Be aware that many products require refrigeration to maintain potency.

Side Effects

Use of L. acidophilus is very safe for most patients, and when they occur, side effects are generally mild. The most common side effect of oral L. acidophilus supplements is gas, and this side effect tends to disappear with continued usage. Other common side effects include diarrhea, abdominal discomfort and upset stomach.


While supplements containing L. acidophilus are generally safe, patients with certain conditions, including the following, should avoid taking them or take them only on the advice and under the close supervision of a physician:

  • Compromised or suppressed immune system: Research suggests that half of the serious infections caused by strains of Lactobacillus occur in people with weakened immune systems.
  • Short bowel syndrome: This condition can allow L. acidophilus to enter the bloodstream and cause infection.
  • High fever that lasts for more than two days: Rarely, probiotics can contribute to existing infections or cause secondary infections in those with strained immune systems.
  • Damaged or artificial heart valve: This increases the chance of bacterial infection.
  • Milk allergy: Some L. acidophilus supplements contain trace amounts of dairy products. This means these supplements could trigger an allergic reaction in those with milk allergies.


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