pH Balance - Clinical Research & Resources

The value of optimal (acidic) pH balance within the vagina is well understood, along with the risks, consequences, and complications that can occur when that balance is disrupted. Researchers continue to study the relationships between vaginal pH and a healthy environment for beneficial lactobacillus species. Existing clinical studies range from determining how certain products can impact vaginal pH, to understanding the efficacy of various means of restoring optimal pH, to confirming preventative measures women can take to reduce vaginal infections and prevent complications.

Influence of pH, temperature and culture media on the growth and bacteriocin production by vaginal Lactobacillus salivarius CRL 1328
M.S. Juarez Tomás, E. Bru, B. Wiesse, A.A.P. De Ruiz Holgado, and M.E.Nader-Macías 

 

The aim of the study is to observe the influence of pH, temperature and culture medium on the growth and bacteriocin production by vaginal Lactobacillus salivarius subsp. salivarius CRL 1328. The optimal growth conditions were recorded in MRS broth, with an initial pH of 6.5 and a temperature of 37 degrees C. The maximum bacteriocin activity was obtained in LAPTg after 6 h at 37 degrees C, and at an initial pH of 6.5 or 8.0. The application of a complete factorial design, and the evaluation of the growth parameters through the Gompertz model, enabled a rapid and simultaneous exploration of the influence of pH, temperature and growth medium on both growth and bacteriocin production by vaginal Lact. salivarius CRL 1328.

 

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A Question for Women's Health: Chemicals in Feminine Hygiene Products and Personal Lubricants
Environmental Health Perspectives, Vol. 122, No. 3, by Wendee Nicole

 

When it comes to reproductive health, research on contraceptives and STIs continues to garner interest worldwide. But a related area—chemical exposures from feminine hygiene products and personal lubricants—has received much less attention. In the United States alone, women spend well over $2 billion per year on feminine hygiene products,3 including tampons, pads, feminine washes, sprays, powders, and personal wipes. But until recently, scant research existed on how chemicals in these products may affect women’s health. As scattered findings emerge, several scientists and interest groups are calling for more research to fill in the gaps. A recent report by the nonprofit Women’s Voices for the Earth (WVE) points out that feminine hygiene products may use ingredients that are known or suspected endocrine-disrupting chemicals (EDCs), carcinogens, or allergens. And while nearly all women use tampons and sanitary pads, black and Latina women use douches, wipes, powders, and deodorizers more often than women of other races, putting them at greater risk of potential chemical exposures.

 

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Efficacy of an acidic vaginal gel on vaginal pH and interleukin-6 levels in low-risk pregnant women: a double-blind, randomized placebo-controlled trial.
Paternoster D.M., Tudor L., Milani M., Maggino T., and Ambrosini A.

 

Vaginal pH of > 4.7 is associated with obstetric complications such as preterm delivery and low birth weight. Topical treatments, able to maintain a physiological vaginal pH, could help in the prevention of vaginal infections. In a randomized, double-blind, placebo-controlled trial, we evaluated the effects of an acidic buffering vaginal gel (Miphil) on vaginal pH and IL-6 levels in pregnant women. The use of the acidic gel in low-risk pregnant women is able to maintain a physiological vaginal ecosystem and prevents the increases of vaginal pH and vaginal IL-6. Prospective and controlled trials are warranted to evaluate whether this acidic gel can reduce obstetric complications linked to vaginal inflammation during pregnancy.

 

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Vaginal pH-balanced gel for the control of atrophic vaginitis among breast cancer survivors: a randomized controlled trial.
Lee Y.K, Chung H.H., Kim J.W., Park N.H., et al.

 

Researchers at the Department of Obstetrics and Gynecology, Seoul National University College of Medicine, in Seoul, South Korea studied the effects of vaginal pH-balanced gel on vaginal symptoms and vaginal atrophy in breast cancer survivors treated with chemotherapy or endocrine therapy. Their findings indicated that vaginal pH-balanced gel could relieve symptoms and improve vaginal health in breast cancer survivors who have experienced menopause after cancer treatment.

 

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The vaginal microbiome: rethinking health and diseases.
Bing Ma, Larry J. Forney, and Jacques Ravel

 

Lactobacillus species dominate vaginal microbiota in the majority of normal and healthy women. However, an appreciable proportion of asymptomatic, otherwise healthy individuals have vaginal microbiota that lack significant numbers of Lactobacillus sp. and harbor a diverse array of facultative and strictly anaerobic microorganisms, challenging the conventional wisdom that presence of lactobacilli equates to ‘normal’ and ‘healthy’ vaginal microbiota. Neither clinical criteria (using either the Amsel and Nugent scoring systems) nor community composition and structure can fully explain symptomatic bacterial vaginosis, which appears to be a multifactorial clinical syndrome with complex and still unknown etiologies. The concept of ‘normal’ and ‘healthy’ vaginal microbiota is difficult to define without a complete understanding of its true function(s) and its effect on host physiology. One might envision separating the concept of ‘normal’ and ‘healthy’ from predisposition to sexually transmitted diseases.

 

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Vaginal pH and Microbicidal Lactic Acid When Lactobacilli Dominate the Microbiota
Deirdre E. O’Hanlon, Thomas R. Moench, Richard A. Cone

 

Fifty-six women with low (0-3) Nugent scores (indicating a lactobacillus-dominated vaginal microbiota) and no symptoms of reproductive tract disease or infection, provided a total of 64 cervicovaginal fluid samples using a collection method that avoided the need for sample dilution and rigorously minimized aerobic exposure. The pH of samples was measured by microelectrode immediately after collection and under a physiological vaginal concentration of CO2. Commercial enzymatic assays of total lactate and total acetate concentrations were validated for use in CVF, and compared to the more usual HPLC method. The average pH of the CVF samples was 3.5 ± 0.3 (mean ± SD), range 2.8-4.2, and the average total lactate was 1.0% ± 0.2% w/v; this is a five-fold higher average hydrogen ion concentration (lower pH) and a fivefold higher total lactate concentration than in the prior literature. The microbicidal form of lactic acid (protonated lactic acid) was therefore eleven-fold more concentrated, and a markedly more potent microbicide, than indicated by prior research. This suggests that when lactobacilli dominate the vaginal microbiota, women have significantly more lactic acid-mediated protection against infections than currently believed. Our results invite further evaluations of the prophylactic and therapeutic actions of vaginal lactic acid, whether provided in situ by endogenous lactobacilli, by probiotic lactobacilli, or by products that reinforce vaginal lactic acid.

 

 


Origins of vaginal acidity: high D/L lactate ratio is consistent with bacteria being the primary source.
E.R. Boskey, R.A. Cone, K.J. Whaley, T.R. Moench

 

It is widely accepted that during times of high oestrogen (during the neonatal period and again during a woman's reproductive years) large amounts of glycogen are deposited in the vaginal epithelium and that the glycogen is anaerobically metabolized to lactic acid. What is not established is whether lactic acid is primarily produced by vaginal bacteria or by vaginal epithelial cells. Human cells can make only L-lactate, while bacteria can produce both D- and L-, thus the D- to L-lactate ratio can indicate the relative contribution of bacterially derived lactic acid. Researchers used chiral HPLC to examine the percentages of D- and L-lactate in vaginal secretions, in primary cultures of bacteria from these vaginal secretions, and in cultures of lactobacillus isolates of vaginal origin. RESULTS: We found that in most vaginal secretion samples, >50% of the lactic acid was the D-isoform (mean 55%, range 6–75%, n = 14). Findings support the hypothesis that vaginal bacteria, not epithelial cells, are the primary source of lactic acid in the vagina.

 

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Vaginal pH balance: Symptoms, remedies, and tests.
Rachel Nall, RN, BSN, CCRN; Reviewed by Holly Ernst, PA-C

 

Keeping vaginal pH levels in balance can help to reduce infections and prevent complications. Doctors rarely rely just on measurements of vaginal pH to diagnose medical conditions, such as yeast infections, or to determine whether or not someone is approaching menopause. However, vaginal pH tests can help to confirm a suspected diagnosis. Women can take steps, such as using probiotic supplements and not douching, to help keep their vaginal pH levels balanced.

 

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