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October 2001; Volume 4; 109-112
By Nassim Assefi, MD
Vaginitis is one of the most common reasons a woman visits a gynecologist, and has been estimated to be the cause of 10 million patient visits each year.1 Bacterial vaginosis (BV) and yeast infections are the leading etiologies of vaginitis in women of reproductive age, comprising approximately 50% and 25% of cases, respectively.2 With the availability of over-the-counter topical antifungals and a growing armamentarium of alternative medicines, many women attempt self-treatment of vaginal symptoms before consulting a health care provider.
Yogurt is one of the cheapest and oldest known non-prescription remedies for vaginitis, first advocated by Nobel-laureate Elie Metchnikoff in 1908.3 While medical professionals have vacillated about the value of yogurt-delivered Lactobacillus therapy for vaginitis over the last century, patients have continued to use yogurt (both orally ingested and douches) to treat their vaginal symptoms. An increased understanding of vaginal physiology and pathogens supports the biological plausibility of using exogenous Lactobacillus from yogurt to restore vaginal health; however, limited in vitro studies and clinical trials have yet to warm the tepid enthusiasm of conventional practitioners to this common alternative practice.
The estrogenated vagina can be thought of as a fortress fiercely guarded by lactobacilli, which produce lactic acid (to maintain a hostile vaginal pH of 4.0-4.5) and bactericidal metabolites, such as hydrogen peroxide (H2O2) as weapons against other organisms. Yeast vaginitis occurs when there is disruption of the vaginal ecosystem and overgrowth of candida organisms. BV results from the proliferation of Gardnerella vaginalis and anaerobic bacteria.
Successful oral yogurt therapy depends upon the survival of lactobacilli through gastrointestinal processing, as therapeutic vaginal colonization is thought to occur from anal migration. Treatment of vaginitis by Lactobacillus recolonization was first described in 1933, and continues to be the rationale for using yogurt, which is a natural source of lactobacilli, for this purpose. Effective topical yogurt treatment (yogurt douching), requires adherence of exogenous lactobacilli to vaginal cells.
Although knowledge of gram-positive rods dominating the flora of healthy vaginas dates back to the late 1800s,4 clearly defining the genus Lactobacillus continues to be a challenging and arduous process. Lactobacillus acidophilus, the predominant Lactobacillus species in the normal vagina, generates H2O2, which correlates with decreased BV and yeast vaginitis when compared to non-H2O2-producing lactobacilli, and also survives digestion. However, Lactobacillus strains from yogurt, including L. acidophilus, have been shown to manifest poorer adherence to vaginal epithelial cells than strains derived from the human vagina.5
Barriers to accepting yogurt therapy for vaginitis reflect several factors: the ready availability of topical and oral antimicrobials (metronidazole and clindamycin for BV and antifungals for yeast infections); the uneven quality of yogurt products on the market; and the paucity of randomized, double-blinded placebo-controlled trials.6 Nevertheless, the common use of alternative medicines for vaginitis (42% of chronic vaginitis patients in one study, of which 50% reported using acidophilus pills and 21% used yogurt7), the recurrence of symptoms (especially BV) despite antimicrobial therapy,2 and the emphasis on avoiding medicines during pregnancy8 have created interest in the medical community regarding the possibility of Lactobacillus replacement by yogurt delivery for vaginitis.
Literature searches of Pubmed, Cochrane Collaboration, CINDAHL, Biosis, Embase, and the Alternative Medicine Alert Index using "yogurt," "yougurt," "yoghurt," and "vaginitis" as key words revealed four relevant studies.
In an open, seven-day trial by Neri and colleagues, 64 pregnant women with BV were randomized to twice-daily doses of yogurt douches or acetic acid tampons.9 Twenty women refusing treatment served as controls. Yogurt douches were made by adding a small amount of water to 10-15 mL of commercially available yogurt (cultures added after pasteurization included more than 108 Colony Forming Units (CFU)/mL of L. acidophilus) and inserting the syringe of liquefied yogurt 4-6 cm into the vagina. The effect of treatment was evaluated four and eight weeks after completion; BV cure was defined by the absence of Amsel criteria (foul-smelling discharge, pH > 4.5, positive amine test, and clue cells on wet mount).10 Two months after treatment, 88% of women using yogurt douches versus 38% of women using acetic acid tampons and 5% of women without treatment were free of BV (P < 0.05 between all groups).
Strengths of the study include using both clinical and laboratory outcomes for eradication of BV and a relatively long follow-up period. Weaknesses include choosing non-randomized patients as the no-treatment/natural history controls, as well as the lack of a pasteurized/non-Lactobacillus yogurt arm to show that Lactobacillus was the active ingredient in the therapy.
A smaller, uncontrolled Japanese study of vaginally delivered yogurt for women with BV showed clinical and laboratory eradication of BV in 55% of cases after three days of douching.11
Hilton and associates conducted a crossover study of Lactobacillus acidophilus-containing yogurt (8 ounces daily) versus a yogurt-free diet for women with recurrent candidal vaginitis.12 Infections were defined as clinical vaginal complaints with a Gram-positive stain for budding yeast, pseudohyphae, an acidic vaginal pH, and a positive culture for Candida species; colonization was a positive vaginal culture with no clinical evidence of vaginitis.
Of 21 eligible patients, only 13 complied with the protocol (eight patients originally assigned to the yogurt arm refused to enter the control phase six months later due to subjective and clinically confirmed improvement). The resulting one-arm investigation followed 13 patients with culture-verified candidal vaginitis for one year: six months with and six months without yogurt ingestion. A significant, threefold decrease in candidal infections was observed in those consuming yogurt, corroborated by a similar decrease in vaginal colonization. Neither patients nor clinical interviewers were blinded to the treatment assignment, although culture results were reported by technicians blinded to identity.
Finally, in a crossover trial, Shalev’s group studied the frequency of vaginitis in women with either yeast infections, BV, or both, who were randomized to consuming roughly 8 ounces of yogurt daily either with or without (pasteurized) live Lactobacillus cultures (at least 108 CFU/mL of L. acidophilus).13 Patients were examined on at least monthly intervals by providers blinded to the type of yogurt ingested. Candidal vaginitis was defined as in Hilton’s study; BV was defined by Amsel criteria.
After two months, there was no significant difference between candidal vaginitis or colonization in the two groups, but BV episodes were significantly decreased (approximately 50%) in those consuming Lactobacillus-containing yogurt. However, of 46 patients randomized to each of the two groups, only seven completed the entire protocol, and the difference in BV infections observed between the two groups decreased with time.
Adverse Effects, Allergy, and Drug Interactions
To date, no serious side effects have been reported following ingestion of or vaginal douching with yogurt.14
Although there have been a few cases of lactobacillemia reported in severely immunosuppressed individuals, all cases have responded to standard antibiotic therapy.6 Douching, particularly high-pressure douching, has the potential to cause pelvic inflammatory disease, ectopic pregnancy, and peritonitis.15 Lactobacillus acidophilus-containing yogurt should be taken 2-3 hours after an antibiotic dose to prevent the bacteria’s death. Lactobacilli also have decreased efficacy in the presence of alcohol.15 Finally, yogurt that contains milk or milk products added after fermentation (such as many of the yogurt products available in the United States) can produce gastrointestinal disturbance in lactose intolerant individuals.16
Dosage and Formulation
The delivery of lactobacilli by yogurt is problematic for several reasons. Yogurt is a food that is not regulated in terms of its composition, nor is it even fully understood. Although yogurt must contain Lactobacillus bulgaricus and Streptococcus thermophilus to be sold,17 it may contain live bacterial cultures (which may or may not contain L. acidophilus, despite advertisements), be pasteurized, or have several added cultures following pasteurization (the most common scenario in today’s commercially available yogurt). Furthermore, claims by dairy product manufacturers about the presence of certain Lactobacilli species do not always ring true when subjected to microbiological testing.18
Yogurt with the greatest therapeutic potential for treating vaginitis should include added cultures of H2O2-producing lactobacilli after pasteurization, preferably L. acidophilus. For lactose-intolerant individuals, yogurt products that are less processed and contain H2O2-producing lactobacilli, such as Bulgarian yogurt and kefir, will minimize gastrointestinal symptoms. It is unknown, though biologically unlikely, whether the fat content of the yogurt significantly affects Lactobacillus colonization.
Sample fat-free, plain yogurt labeling
|Serving size||8 oz|
|Live Cultures Added|
The high dropout rates in the above studies, patient reluctance to apply messy topical yogurt therapy to the genital area, in vitro studies suggesting decreased adherence of yogurt-derived lactobacilli to vaginal cells, and the potential dangers and medical bias associated with douching suggest daily oral ingestion of yogurt is the optimal mode of delivery. Although there is a paucity of high-quality studies suggesting standardized dosing and duration of treatment, eating 8 oz of yogurt daily for one week for acute vaginitis (and one month for chronic vaginitis) will eradicate BV or candidal symptoms in those women for whom yogurt therapy will be effective.
Two studies of yogurt douching and one study of orally ingested yogurt suggest clinical benefit for BV.
Oral yogurt ingestion may improve both candidal infections and bacterial vaginosis, and carries very little risk. However, a lack of trials comparing yogurt therapy to conventional treatments, inconsistencies in product quality, the paucity of high-quality studies upon which standardized dosing and duration of treatment can be established, and the fact that a significant portion of women with vaginitis erroneously self-diagnose candida or BV when they instead have gonorrhea, chlamydia, and trichomonas limit its universal recommendation.
Patients with confirmed diagnoses of yeast vaginitis or bacterial vaginosis may benefit from daily ingestion of 8 oz of yogurt with live H2O2-producing lactobacilli for treatment of their current and chronic vaginal symptoms; yogurt douching also is likely to be beneficial, but is accompanied by potentially greater risks.
Dr. Assefi is Attending (Clinician-Teacher), Departments of Medicine and Obstetrics/Gynecology, Complementary and Alternative Medicine Liaison, School of Medicine, University of Washington in Seattle.
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