Evidence

These uses have been tested in humans or animals.  Safety and effectiveness have not always been proven.  Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Key to grades

A
Strong scientific evidence for this use
B
Good scientific evidence for this use
C
Unclear scientific evidence for this use
D
Fair scientific evidence against this use (it may not work)
F
Strong scientific evidence against this use (it likely does not work)

Grading rationale

Evidence gradeCondition to which grade level applies
B

Vaginal disorders

There is good evidence supporting the use of L. acidophilus or yogurt enriched with L. acidophilus for the treatment of vaginal infections. More evidence is needed to support the use of L. acidophilus in treating vaginal yeast infections such as candidiasis, as well as restoring microorganisms in the vagina after treatment for infections. Several studies have used L. acidophilus in combination with other probiotics or supplements, such as vitamin B.
C

Allergic skin reactions

Taking Lactobacillus by mouth along with itraconazole has been shown to help treat scaly, itchy rashes. There is also some evidence that Lactobacilli may help prevent this condition. However, other studies did not produce the same results. Some found that L. acidophilus supplementation may increase the risk of sensitivity to food allergens, while others suggest that L. acidophilus may actually decrease sensitivity. More research is needed in this area.
C

Anemia

Limited research shows that L. acidophilus combined with iron amino acid chelates may improve measures of anemia, including red blood cell counts and levels of hemoglobin. However, it may lack benefits on other measures, such as cell volume, cell hemoglobin, and serum iron levels. Further research is needed before conclusions can be made.
C

Ankylosing spondylitis

Limited research suggests that a probiotic combination containing L. acidophilus may help reduce symptoms of ankylosing spondylitis, arthritis of the spine. However, further research is needed to confirm this and to determine the effects of using L. acidophilus alone.
C

Asthma

Limited research found unclear and negative evidence to support the use of L. acidophilus in treating allergic asthma. More research is needed in this area.
C

Cavities

Limited research shows that eating probiotic ice cream containing L. acidophilus may reduce levels of microorganisms in the saliva that may be linked to cavities. Further research is needed to confirm this and to identify the effects of L. acidophilus alone.
C

Diabetes (type 2)

Limited research suggests that taking capsules containing L. acidophilus may lower insulin sensitivity in people who have type 2 diabetes. Further research is needed.
C

Diarrhea prevention

It is unclear whether L. acidophilus, or probiotics in general, may prevent diarrhea. One study found that L. acidophilus alone lacked benefits in preventing traveler's diarrhea, while others found conflicting results when using combination probiotic strains (such as Lactinex™, a blend of L. acidophilus and L. bulgaricus). There is also conflicting evidence on whether probiotic treatments containing L. acidophilus help prevent antibiotic-associated diarrhea in babies and adults, as well as whether probiotics prevent diarrhea more effectively in children.
C

Diarrhea treatment (children)

The World Health Organization (WHO) reports that treating acute diarrhea in children involves drinking plenty of fluids and supplementing with heat-killed L. acidophilus. However, studies have found conflicting results, and it is still unclear whether L. acidophilus shortens the duration of diarrhea. One study reported that a combination of heat-killed L. acidophilus and zinc therapy had negative results, compared to zinc alone. It is also unclear whether live Lactobacilli, alone or in combination with other treatments, are effective in treating diarrhea. An early study found that live probiotic blends containing L. acidophilus were ineffective, while others reported probiotic treatments to be effective.
C

Eye diseases

Low-quality studies found that eyedrops that contain L. acidophilus may help reduce symptoms of an eye disease called keratoconjunctivitis sicca. Further research is needed before conclusions can be made.
C

Flu

Limited research suggests that L. acidophilus may reduce fever and the duration of flu symptoms. However, further research is needed before conclusions can be made.
C

Hay fever

Animal research suggests that L. acidophilus may reduce allergic immune responses. There is some evidence that milk containing L. acidophilus may relieve hay fever symptoms, but other studies found conflicting results. More research is needed to understand how L. acidophilus may relieve allergies.
C

Helicobacter pylori infection

Some strains of probiotic bacteria may block the growth H. pylori and treat or prevent H. pylori infection. However, studies suggest that L. acidophilus lacks this effect on H. pylori. Yogurt containing L. acidophilus and B. lactis was reported to decrease H. pylori activity and improve antibiotic therapy in H. pylori infections, but this effect was likely due to B. lactis. Other Lactobacillus species may be more effective, such as L. paracasei, L. rhamnosus, L. plantarum, L. casei, and L. johnsonii.
C

Hepatic encephalopathy

One study found that probiotics containing L. acidophilus may reduce toxins in the blood, which may help prevent hepatic encephalopathy (confused thinking due to liver disorders). However, other studies found unclear or negative evidence. Further research is needed in this area.
C

Immune function

Probiotics may help enhance the immune system at an early age and prevent allergic disorders later in life. Combination probiotic supplements have been shown to affect the adult immune system. Early studies found that L. acidophilus supplementation may affect early immune responses to allergens and vaccines. However, there is conflicting evidence. Effects on other immune disorders remain unclear.
C

Intestinal disorders

Studies report that combination probiotic preparations containing L. acidophilus may help treat intestinal disorders such as irritable bowel syndrome (IBS). L. acidophilus may also help standard therapies for partial bowel blockages. However, combination probiotic preparations with L. acidophilus lack benefits in critically ill people with gut disorders. There is unclear and conflicting evidence supporting the use of L. acidophilus alone in treating IBS.
C

Lactose intolerance

Lactic acid bacteria are thought to promote lactose digestion by breaking down lactose or releasing compounds that help digest it. However, there is unclear and conflicting evidence to support the use of L. acidophilus for this purpose.
C

Liver disease

Limited research using a combination treatment has shown that probiotic treatment may improve the symptoms of liver disease in certain patients, but further studies are still needed before conclusions may be made. In addition, studies assessing the effects of L. acidophilus alone are still needed.
C

Necrotizing enterocolitis (NEC) prevention

Limited research suggests that treating newborns with solutions containing living or killed L. acidophilus bacteria may help reduce necrotizing enterocolitis, a disorder involving the death of intestinal tissue. Further research is needed before conclusions can be made.
C

Pneumonia

Limited research shows that pneumonia has been treated with a combination of antibiotics and L. acidophilus. However, further details are unclear.
C

Pouchitis

Limited research suggests that a combination therapy involving L. acidophilus may prevent relapse of pouchitis, inflammation of the ileal pouch after surgery. Further research is needed to confirm these results and to identify the effects of L. acidophilus alone.
C

Pregnancy problems

Vaginal disease caused by bacteria may lead to preterm delivery and low birthweight. There is some evidence that L. acidophilus may help prevent preterm delivery, though more evidence is needed.
C

Radiation-induced diarrhea

Limited research shows that diarrhea caused by radiation may be reduced with combination therapy involving L. acidophilus. However, further research is needed to confirm these results and to identify the effects of L. acidophilus alone.
C

Sepsis

Limited research shows that treating newborns with solutions containing living or killed L. acidophilus bacteria may help prevent sepsis, a severe response to bacteria or germs. More studies are needed before conclusions can be made.
D

High cholesterol

There is conflicting evidence as to whether combination probiotics containing L. acidophilus may benefit high cholesterol. Although L. acidophilus has been shown in some studies to lower cholesterol, this effect may be due to bile acids.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Acne, AIDS, arthritis, breast cancer, cancer, cancer prevention, canker sores, colon cancer, constipation, Crohn's disease, diaper rash, diverticulitis (disorder of the intestines), E. coli infection in cancer patients, fever blisters, gum disease, heartburn, heart disease, hives, indigestion, infection, inflammation, preoperative prevention of infections or gut bacteria loss, prostate cancer, respiratory tract infections, stomach ulcer, thrush, urinary tract infection.

This evidence-based monograph was prepared by The Natural Standard Research Collaboration

www.naturalstandard.com