Every part of the body that comes into contact with the outside world has a microbiome. There’s the gut, of course, with its regular exposure to food and water, but there are also the lungs, skin, mouth, eyes, and genitals.
The vagina, in particular, is home to a rich ecosystem of bacteria that, when balanced and healthy, helps to prevent infections — from routine yeast infections and bacterial vaginosis to HIV. A healthy vaginal microbiome also helps keep more minor irritations, like itching and pungent odor, at bay.
The vaginal microbiome is made up of many different bacteria, including lactobacilli. Lactobacilli produce lactic acid, and it is the lactic acid’s job to keep the pH of the vagina low, explains Leah Millheiser, MD, director of the Female Sexual Medicine Program at Stanford University School of Medicine’s Department of Obstetrics and Gynecology. On a pH scale of 1 to 14, 7 is considered neutral; under 7 (low pH) is considered acidic; and over 7 (high pH) is considered alkaline (or basic). “It’s ideal to have the vaginal pH in the 3.5 to 4.5 range,” says Millheiser.
Anna Cabeca, DO, author of The Hormone Fix, agrees that optimal vaginal pH is in the 3.5 to 4.5 range. “An acidic vagina is a first line of defense against infection,” she says.
A variety of factors can knock the vaginal microbiome out of balance and increase vaginal pH, including simply getting older. “One of the causes of elevated vaginal pH is perimenopause,” says Millheiser. Perimenopause is the period of time in a woman’s life that follows her peak reproductive years and precedes menopause.
It’s characterized by shifts in estrogen, and less circulating estrogen in a woman’s body kicks off a cascade of events that disrupts the vaginal ecosystem. “The lactobacilli of the vagina love glycogen, but the walls of the vagina are rich in glycogen only when a woman has a good amount of estrogen in her body,” says Mary Jane Minkin, MD, OB/GYN, professor in the department of Obstetrics, Gynecology, and Reproductive Sciences at the Yale University School of Medicine. “When the glycogen is gone, the lactobacilli die and vaginal pH goes up.”
Lower levels of estrogen are also linked with vaginal dryness. “A dry vagina is more easily invaded by bacteria,” says Minkin.
The same problems persist and often get worse during menopause, when estrogen production drops off dramatically. “In menopause, the vaginal pH becomes more basic [or alkaline],”says Millheiser. “And women tend to get more bacterial vaginosis and yeast infections.”
But age isn’t the only factor. Certain types of birth-control medication can increase pH for some women, notes Millheiser. And douching, which can change the vaginal microbiome and leave women more susceptible to vaginal infections and sexually transmitted infections, is uniquely terrible for the vaginal ecosystem. “Douching is the worst thing you can do for your vagina,” Millheiser says.
Exposure to synthetic fragrances and chemicals, either through “feminine hygiene” products or harsh laundry detergents, can also irritate and disrupt vaginal tissue, says Cabeca, as can a high-sugar diet.
“Yeast loves sugar,” says Minkin. “Don’t eat a cookie if you have a yeast infection. A high-sugar diet makes yeast happy.”
“Honeymoonitis” is another common cause of imbalanced microbes and high vaginal pH. “A patient comes in, they have a new lover, and they have bacterial vaginosis or a UTI and they’re wondering what happened,” says Cabeca. During intercourse, new bacteria is introduced to the vaginal ecosystem, and it can also travel to the urethra (causing a UTI). This can happen no matter the sex of the new sexual partner, but it may be especially pronounced when a woman has sex with a cisgendered man. “Sperm are alkaline and that can affect vaginal pH,” Cabeca explains.
A lot of everyday interventions support a balanced vaginal ecosystem and low vaginal pH. Here’s what experts recommend.
To reiterate, if you’re worried about the health of your vaginal ecosystem, or any other genital issue, like pain during sex or during urination, talk with a professional. Too many women keep vaginal issues to themselves out of embarrassment or because they think it is an unavoidable part of getting older.
“Vaginal health is important for the duration of our lives,” says Cabeca. “So many women just power through symptoms because they are getting older. They think they have to suffer. But it can stop. No matter how old you are, vaginal health can be improved.”