Randomized study to determine whether the vaginally isolated strains of Lactobacillus gasseri and/or Lactobacillus crispatus can colonize the vagina when taken orally for 18 days. Secondary outcomes comprise evaluation of safety, tolerability, impact on vaginal microbiota and vaginal pH

Double blind, randomized, placebo-controlled biomedical research study to determine whether supplementation with the vaginally isolated strains of Lactobacillus gasseri and/or Lactobacillus crispatus can colonize the vagina. Healthy women who meet inclusion and exclusion criteria will be randomized 1.5:1.5:1 to one of the following study groups: group one will receive L.gasseri for 18 days (1 capsule/day), group two will recieve the combination of L.gasseri and L.Crispatus for 18 days (1 capsule/day) and the other will receive placebo, starting the day after menstruation is over. Main study outcome will be colonization throughout the study, which will be determined by analysis of specific strains by qPCR. Secondary outcomes comprise comprise evaluation of tolerability, impact on vaginal microbiota, vaginal pH and adverse events.

Inclusion Criteria:

• Healthy women
• Reproductive age 18-45 years

Exclusion Criteria:

• Vaginal infection or symptoms (AMSEL criteria).
• Relevant disease (immunodeficiency, cervicovaginal pathology, diabetes, estrogen-dependent tumors, inflammatory bowel disease, atrophic vaginitis, pancreatitis)
• Suffer from chronic diarrhea or constipation or short bowel syndrome,
• Having taken systemic or vaginal antibiotics or antifungals during the month prior to study entry.
• Pregnant women or willing to be during the study, lactating women.
• Having taken another probiotic during the month prior to study entry orally or vaginally. This includes food supplements or foods supplemented with probiotics such as Actimel, Activia or similar.
• Intake of immunomodulators or systemic corticosteroids.
• History of alcohol or drug abuse.
• Menopausal women.
• Use of the IUD.
• Use of spermicides or vaginal lubricants during the month prior to study entry.
• Very irregular periods or low probability of going at least 18 days without menstruation (short cycles).
• Have participated in a clinical trial during the month prior to entering the study.
• Not being able to follow or understand study procedures. This includes not being willing to maintain sexual abstinence during the 24 hours prior to each vaginal sample collection.
• Any other condition not compatible with the study according to the investigators