How Your Diet Influences the Vaginal Microbiome

• Study participants were mostly young women — The cross-sectional study involved 113 sexually active women between the ages of 19 and 30, with a median age of 21 years. All were in good health and free from chronic disease, infections, or pregnancy.

• The participants provided two self-collected vaginal samples — These were taken during the late follicular phase (the final stage in the menstrual cycle). One sample was tested for sexually transmitted infections (STIs) and the other was used for metabolomic analysis and microbiota profiling.

• The vaginal bacteria were grouped into different categories — These categories show which types of bacteria are most dominant. The team also identified the different types of Lactobacillus, a strain known to help protect vaginal health.

• The researchers also evaluated the participants’ food intake — They used a food questionnaire with 188 food items classified into 24 categories. The dietary data included how much alcohol, protein, fiber, and carbohydrates each woman regularly consumed.

“Nutritional data were processed and analyzed for alcohol, energy, and macronutrient intake, and macronutrient balances were examined using Compositional Data Analysis (CoDA), employing additive log-ratio transformations,” News-Medical.net explains.

“Statistical analyses included correlation studies, diversity indices, and multinomial logistic regression adjusted for potential confounders such as stress, contraceptive use, age, and body mass index (BMI).”²

• A high intake of animal protein and alcohol was associated with high amounts of harmful bacteria — In women whose diets were rich in meat and alcohol, the bacterial communities shifted into CST IV, meaning they have more anaerobic bacteria and fewer healthy Lactobacillus species.

• In particular, Gardnerella and Prevotella strains are prevalent in these participants’ vaginal microbiome — These two microbes are the main culprits behind bacterial vaginosis (BV), a condition marked by abnormal discharge, odor, irritation, and increased risk of sexually transmitted infections and pregnancy complications.

• These dysbiotic communities were linked to increased glucose and simple sugar metabolites — These conditions favor the growth of unwanted bacteria. These microbial groups also had more diverse species present, which may sound good, but in the vaginal environment, more diversity usually signals an imbalance. A healthy vaginal microbiome is one where just a few dominant good bacteria keep the ecosystem stable and defend against invaders.

• Meanwhile, consuming more vegetables, fiber, and healthy carbohydrates led to more favorable microbiome profiles — Specifically, those with higher intake of these nutrients had more beneficial Lactobacillus strains, which are protective for vaginal health, helping lower infection risk.

• Bacterial balance wasn’t just about which microbes were present — It also came down to the chemical compounds those microbes were producing. In healthy vaginal environments dominated by Lactobacillus strains, researchers found higher levels of branched-chain amino acids like leucine and isoleucine, and antioxidants that support local immune defenses and help keep vaginal pH low, preventing the overgrowth of BV-causing bacteria.

• These results support the idea of a “vagina-gut axis” — This is a two-way street where dietary nutrients modulate not just the digestive system but reproductive health as well. The researchers concluded:

“A healthy diet could preserve the vaginal homeostasis by regulating the trafficking of bacterial species across the vagina and gut (bacterial translocation), in turn modulating the level and type of metabolites produced by the microbiota, acting as indirect players of the vagina-gut axis.

In conclusion, we highlighted that specific dietary habits (i.e., reduced consumption of alcohol and animal proteins, higher intake of linolenic acid) can have a beneficial impact on the vaginal environment, through the maintenance of a microbiota mostly dominated by ‘protective’ Lactobacillus species …”³

• EPA and DHA surpass ALA in terms of their bioavailability — To put it simply, the body uses these two animal-based omega-3s more easily, making their benefits more easily attainable.

• Plant sources of ALA are also loaded with polyunsaturated fats (PUFs) — Most of the foods high in ALA — nuts, seeds, flaxseeds, and chia seeds — also contain high amounts of linoleic acid (LA), a PUF that disrupts the mitochondria and increases inflammation. Hence, excessively consuming these foods could be causing more damage to your health.

• The study followed a group of 40 women during all three trimesters — Both their dietary habits and the bacteria living in their vaginal tract were closely monitored during this time. The participants, who came from different ethnic backgrounds and were between 18 and 45 years old, were all considered low-risk pregnancies.

Each woman completed food questionnaires in the first, second, and third trimesters, while also self-collecting vaginal samples for microbiome analysis. The goal was to determine if better eating habits were linked to a healthier vaginal environment, which could reduce the risk of complications like preterm birth and bacterial infections.

• What the researchers found was eye-opening — Diet quality had a consistent and measurable impact on which bacteria showed up in each woman’s microbiome. Women who scored higher on the Healthy Eating Index (HEI) — a tool that measures how closely their diets align with recommended dietary guidelines — were more likely to have protective bacteria strains.

• The biggest dietary driver of this beneficial balance was carbohydrate intake — Women who got more than 49% of their daily calories from carbohydrates had a microbiome dominated by good bacteria, while those who ate fewer carbs showed a rise in less favorable species and anaerobic bacteria that are linked to vaginal dysbiosis, which raises the risk for infection, inflammation, and complications during labor.

• Timing made a difference, too — In early pregnancy, better diet scores were associated with fewer overall bacterial species, which is a good thing in the vaginal ecosystem. Unlike the gut, where diversity is usually beneficial, the vaginal microbiome works best when just a few dominant good species hold their ground. This low-diversity, Lactobacillus-rich environment is what keeps things balanced and prevents harmful bacteria from taking over.

• The biological mechanisms at play here come down to something simple but powerful — glycogen — When a woman eats enough carbohydrates, her vaginal cells store glycogen, a starch-like compound that acts as food for beneficial Lactobacillus species. These bacteria convert glycogen into lactic acid, which keeps vaginal pH low and stops pathogens in their tracks. Without enough glycogen, the vaginal microbiome becomes imbalanced.

• Hormonal shifts also play a role — Estrogen, which rises steadily throughout pregnancy, helps the body build and store glycogen in vaginal tissue. However, not getting enough carbs means it can’t do its job effectively. That’s why what women eat matters just as much as what their hormones are doing.

• Carbs from ultraprocessed foods damage health — Avoid carb choices that come in a box, bag, or bar with a long list of hard-to-pronounce ingredients. Refined carbs, like white bread, cookies, breakfast cereals, store-bought baked goods, and granola bars, spike blood sugar, damage both the gut and vaginal microbiome.

• Optimize gut health before consuming complex carbs — Symptoms like bloating, food intolerances, or loose stools, indicate that a compromised gut, and consuming complex carbs will only feed the bad bacteria. The key is to heal the gut first — stick to easy-to-digest carbs like white rice and whole fruit to fuel the body without overfeeding the bad microbes.

• Reintroduce fermentable fibers once the gut is healed — If the symptoms are gone, consider adding in small amounts of fibers that feed the good gut bacteria. Start with cooked and cooled white potatoes or green bananas, which contain resistant starch.

1. Eliminate linoleic acid (LA) from your diet — This omega-6 fat promotes inflammation and has been linked to microbial imbalance in the body. If you’re using seed oils like soybean, corn, sunflower, or safflower oil in your cooking or eating a lot of processed foods that contain them, you’re likely getting too much LA.

Replace these oils with healthier fats like grass fed butter, tallow, or ghee. If you often snack on chips or eat out often, cutting back on fried and processed foods will help reset your inflammatory load and support a healthier microbiome.

2. Avoid eating processed meats — As noted by the featured study, eating more processed meats like bacon or deli meat allows harmful bacteria to thrive, which leads to bacterial vaginosis. I recommend getting your protein from whole food sources like pasture-raised eggs, raw dairy, grass fed beef, and wild-caught fish.

3. Skip the alcohol — Even having a few cocktails a few times a week can affect the vaginal ecosystem. Both featured studies linked alcohol intake with increases in bad bacteria tied to BV and increased vaginal pH. Cutting back or eliminating alcohol completely could be one of the fastest ways to reset the balance and prevent unpleasant vaginal conditions.

4. Avoid douching — Despite what is shown in many advertisements, douching is not a healthy, recommended practice. Flushing the vagina with water or another cleansing agent only serves to disrupt its healthy bacteria balance, giving bad bacteria the advantage. According to the U.S. Department of Health and Human Services’ (HHS) Office of Women’s Health:⁷

“Douching can change the necessary balance of vaginal flora (bacteria that live in the vagina) and natural acidity in a healthy vagina. A healthy vagina has [both] good and harmful bacteria. The balance of bacteria helps maintain an acidic environment. The acidic environment protects the vagina from infections or irritation.

Douching can cause an overgrowth of harmful bacteria. This can lead to a yeast infection or bacterial vaginosis. If you already have a vaginal infection, douching can push the [infection-causing] bacteria up into the uterus, fallopian tubes and ovaries. This can lead to pelvic inflammatory disease, a serious health problem. Douching is also linked to other health problems.”