Probiotics are thought to be beneficial in two ways. First, probiotics reinforce the integrity of the intestinal lining as a protective barrier to prevent harmful organisms or materials from crossing into the body's bloodstream. Second, some probiotics have been found to secrete antimicrobial substances known as "bacteriocins," which inhibit harmful bacteria.
Probiotics may help manage some food allergies by reinforcing the barrier function of the intestinal lining noted above.
The effectiveness of probiotics is linked to their ability to survive the acid of the stomach and the alkaline conditions in the duodenum (the passage from stomach to small intestine), as well as their ability to adhere to the intestinal lining and colonize the colon.
Antibiotic (probiotics to reduce related adverse effects):
An increasing number of studies support the use of probiotics as a supplement to antibiotic therapy. Probiotic supplementation during a course of antibiotics may reduce the adverse effects of antibiotics in the intestinal environment. This includes reducing growth ofClostridium difficilebacteria, which can lead to colitis -- a common complication of antibiotics, especially in the elderly. Some probiotics may also help prevent the development of antibiotic resistance. In acutely ill children, synbiotics have been linked to greater weight gain and fewer bacterial illnesses after antibiotics are ended. The evidence consistently supports supplementation of antibiotics.
Helicobacter pylori infection:
Antibiotics are the main treatment to eradicateHelicobacter pylori, the cause of most stomach ulcers. Side effects commonly include bloating, diarrhea and taste disturbances. Probiotics reduce these side effects and generally help people tolerate the treatment. They may also reduce levels ofH. pyloriin children and adults. Yogurt containing probiotics suppressesH. pyloriinfection and may lead to more complete eradication during antibiotic treatment.
Atopic dermatitis (eczema):
Probiotics show promise for treating or preventing atopic eczema/dermatitis syndrome in children. Infants benefit when their mothers take probiotics during pregnancy and breastfeeding. Direct supplementation of infants may reduce incidence of atopic eczema by as much as half. It may also reduce cow's milk allergy and other allergic reactions during weaning. Probiotics may stabilize the intestinal barrier function and decrease gastrointestinal symptoms in children with atopic dermatitis. Children do differ, however, in their responsiveness to specific probiotics.
Liver cirrhosis may be accompanied by an imbalance of intestinal bacteria flora. Probiotic supplementation in cirrhosis patients has been found to reduce the level of fecal acidity (pH) and fecal and blood ammonia, which are beneficial changes.
There is recent evidence that supplementation withLactobacillus caseimay help reduce the recurrence of colorectal tumors in patients who have previously undergone surgery for colon cancer.
Short-term consumption of probiotic-containing cheese may benefit dental caries. There is also evidence that the probioticLactobacillus rhamnosusGG, when added to milk, may help reduce dental carries in young children.
Diarrhea in children (nosocomial):
LactobacillusGG may reduce the risk of nosocomial (originating in a healthcare setting) diarrhea in infants, particularly cases caused by rotavirus gastroenteritis.
There is tentative support for probiotics to prevent diarrhea in adults and children. Supplementation may benefit HIV-positive men, and yogurt containingLactobacillus caseimay help reduce incidence in healthy young adults. Children may benefit fromBifidobacterium lactis(strain Bb 12) added to their formula.
Diarrhea treatment (children):
Probiotics may reduce the duration of diarrhea and related hospital stays in children. Fermented formula and formula supplemented with probiotics may reduce both the number and duration of episodes of diarrhea.
There is evidence that young children (ages 6-36 months) who receive infant formula withBifidobacteriaBb12 supplementation may achieve faster growth than without the supplementation.
Research suggests that probiotics, especially those in milk or food, may help boost the immune system. However, commercially produced yogurt may not be as effective. More studies are needed, particularly with yogurt, to give recommendations.
Limited evidence with day care children suggests supplementation withLactobacillusGG may reduce number of sick days, frequency of respiratory tract infections, and frequency of related antibiotic treatments.
Fermented milk (with yogurt cultures andL. caseiDN-114001) may reduce the duration of winter infections (gastrointestinal and respiratory), as well as average body temperature, in elderly people.
Probiotics may reduce duration of symptoms in adults and children with infectious diarrhea by 17 to 30 hours. Effective forms includeLactobacillusstrain GG,Lactobacillus reuteri, combinationLactobacillus rhamnosusandLactobacillus reuteri, and combinationLactobacillus acidophilusandLactobacillus bifidus. More studies are needed to evaluate types, dosages, duration of treatment, and relationships to specific pathogens.
Irritable bowel syndrome (IBS):
Many types of probiotics have been shown to moderately reduce symptoms of IBS, including pain, gas, bloating, and stool frequency. There is also some evidence that probiotics may reduce swelling and improve quality of life. However, not all studies show beneficial effects.
Supplementing withLactobacillus plantarum299 may help prevent pancreatic infection (sepsis), reduce the number of operations needed, and reduce the length of hospital stay in treatment of acute pancreatitis.
Probiotics may help treat or prevent radiation-induced diarrhea in cancer patients.
E. coliNissle 1917 appears to be as effective as the drug Mesalazine, but is not currently available in the United States. A variety ofBifidophiluspreparations have shown effects of preventing relapse or maintaining remission. These includeBifidophilusalone,Bifidophilusin fermented milk products, and a synbiotic preparation. A probiotic combination consisting of VSL#3 plus balsalazide may be more effective than balsalazide or Mesalazine alone. More studies are needed to more clearly determine what outcomes can be expected.
There is promising early evidence that probiotics may help treat allergic conditions, especially allergic skin disorders in infants. Most studies have tested probiotics in children, teenagers, and young adults. Some evidence also suggests that probiotics help reduce swelling caused by allergies. However, study results are mixed for inhalant allergies, such as allergic rhinitis (nasal inflammation and discharge). More research is needed.
Combining a probiotic yeast (Saccharomyces boulardii) with antibiotics in the treatment of acute amoebiasis (amoebic dysentery) may decrease the duration of symptoms. More studies are needed to determine recommendations for probiotics in acute amoebiasis.
plus probiotics may help prevent asthma attacks in school-age children with intermittent or mild persistent asthma. More research with probiotics alone is needed.
As a bacterial reservoir, the nose may harbor many varieties of potentially disease-causing bacteria. There is limited evidence that probiotic supplementation may reduce the presence of harmful bacteria in the upper respiratory tract. More studies are needed to establish this relationship and its implications for health.
Vaginal suppositories containing probiotics may be effective in the treatment of bacterial vaginosis. Eating yogurt enriched withLactobacillus acidophilusmay also be beneficial. However, not all applications of probiotics show benefit. Additional research is necessary before firm conclusions can be reached regarding what probiotics and what methods can lead to reliable results.
There is limited evidence suggesting probiotics may help reduce low densitylipoproteins (LDL) cholesterol, a risk factor for cardiovascular disease, in overweight people. These findings are tentative and more evidence is needed to arrive at firm conclusions.
Cardiovascular risk reduction (smokers/atherosclerosis):
One study suggests probiotic supplementation might reduce blood pressure and some biochemical risk factors for cardiovascular disease (leptin and fibrinogen). This implies a possible protective effect against atherosclerosis. However, more studies are needed to confirm such effects.
There is not enough evidence on which to form conclusions for use of probiotics in collagenous colitis.
Use of probiotics with constipation has had mixed results. Some research suggests that they may help reduce symptoms in patients with long-term constipation. However, another study did not show effectiveness in young children. More studies are needed to determine what forms of probiotics might be effective in constipation.
Probiotics may help treat acute diarrhea.Saccharomyces boulardiiand a probiotic formula Escherichia coli Nissle 1917 (EcN) solution have been shown to moderately improve diarrhea in children. However, all probiotic preparations may not be effective.
Although some data support the use of probiotics for treatment and prevention of antibiotic-associated diarrhea (AAD), other studies have found no benefit. Although probiotics are considered a safe and reasonable approach for AAD, larger and better-designed studies are needed for definitive recommendations.
Diarrhea (chronic bacterial overgrowth-related):
There is limited evidence suggesting probiotics might help in treatment of bacterial overgrowth-related chronic diarrhea. More studies are needed to provide guidelines for this use.
Diarrhea (Clostridium difficile):
There is limited evidence suggesting that probiotics may reduce recurrence ofClostridium difficileafter antibiotic therapy. However, more studies are needed to provide definitive guidelines about this use.
Probiotic capsules (containingLactobacillus rhamnosusGG and LC705,Bifidobacterium breve99 andPropionibacterium freudenreichiiJS) did not protect against ear infections in children. More research is needed to confirm these findings.
Hepatic encephalopathy (confused thinking due to liver disorders):
Initial studies in minimal hepatic encephalopathy are encouraging. Probiotics and prebiotics may lead to improvement of symptoms and may be an alternative to lactulose for management of this condition in people with cirrhosis. However, more studies are needed to determine the role of probiotics in this condition.
There is conflicting evidence regarding the effects of probiotic-enriched dairy products on lowering blood levels of total cholesterol or low-density lipoprotein ("bad cholesterol"). More studies are needed.
Results are mixed regarding the ability of probiotics to reduce infective complications of medical treatment. Reduced incidence of infection has been seen in patients treated for brain injury, abdominal surgery, and liver transplantation. Other studies have shown no such reduction in elective abdominal surgery and critical care patients.
Infections (rotavirus nosocomial):
Children receivingBifidophilus-supplemented milk-based formula may be protected against rotavirus infection.LactobacillusGG has shown mixed results, while early evidence suggests thatL. rhamnosusis not effective. Some studies suggest shorter duration of diarrhea, less chance of a protracted course, and faster discharge from the hospital withLactobacillusGG, while others suggest it is ineffective compared to breast-feeding. More studies are needed to determine the optimal use of probiotics in rotavirus nosocomial infection.
Inflammatory bowel disease (IBD):
It is unclear if probiotics can help treat inflammatory bowel disease (IBD). Study results are mixed.Saccharomyces boulardii,E. coliNissle, probiotics, yogurt, and high doses of probiotics have shown the most promise. More research is needed.
Supplementation of infant formulas with probiotics is a potential approach for the management of cow's milk allergy, but there is conflicting evidence as to whether it improves digestion of lactose. More research is needed in this area a before a conclusion can be drawn.
Necrotizing enterocolitis (NEC) prevention:
Little evidence is available on the effects of probiotics in prevention of NEC. Study results conflict. Further studies are needed to determine the effectiveness of this application.
Fermented milk containing the probioticL. johnsoniiLa1 may improve nutritional status in the elderly. More research is needed to confirm these results.
Early research suggests that probiotics may help prevent peptic ulcers. However, more research is needed to determine if this is an effective therapy.
There is insufficient evidence to draw any firm conclusions. More research is necessary.
Limited evidence suggests a probiotic preparation (VSL#3, containingLactobacilli,Bifidobacteria, andStreptococcus salivariussubspecies thermophilus) may be effective in prevention of pouchitis. Notably, discontinuation appears to be followed by relapse, while continuation apparently maintains remission and better quality of life.LactobacillusGG supplementation, however, has had conflicting results in preventing flare-ups. More studies are needed to arrive at concrete recommendations.
Rheumatoid arthritis (RA):
In a small studyLactobacillusGG was associated with improved subjective well being and trends in reduced symptoms, though not statistically significant. More studies on the effects of probiotic in RA are needed.
Supplementation in preterm and very low birthweight infants:
Probiotics, when added to formulas or breast milk, may foster better growth and higher counts of healthful bacteria in the gut of preterm infants. They may also boost the immune system and improve feeding tolerance. However,LactobacillusGG may not be effective. More studies are needed to clarify specific guidelines for probiotics in preterm infant care.
Early research suggests that cheese containing probiotics may help reduce the risk of a fungal mouth infection, called thrush, in the elderly. More research is needed in this area.
Urinary tract infection:
Studies ofLactobacilluspreparations have had mixed results. Evidence suggests a combination ofLactobacillus rhamnosusGR-1 andL. fermentumRC-14 may reduce potentially harmful vaginal bacteria and yeast in healthy women. Other studies have found no benefit for women or pre-term infants. More studies are needed to determine effectiveness of probiotics in urinary and urogenital tract infections.
Vaginal candidiasis (yeast infection) :
Probiotics have not been adequately studied for the prevention or treatment of vaginal yeast infections. More research is needed in this area before a conclusion can be drawn.
Bacterial infection (translocation):
Bacterial translocation (passage of bacteria from the gut to other areas of the body where they can cause disease) is of special concern in surgery. Limited evidence suggests that supplementation with probiotics may not reduce this problem.
Diarrhea (HIV patients on antiretroviral therapy):
Probiotic therapy is well tolerated in HIV infected patients on antiretroviral therapy, but may not be helpful for gastrointestinal symptoms.
Probiotics have been used in the vagina immediately after oocyte retrieval during IVF, but they do not appear to have an effect on vaginal colonization or pregnancy rate in IVF cycles.