I Asked a Harvard Gynecologist Every Q Women Are Too Embarrassed to Ask

July 29, 2026

AI Summary

5 min read

The Vaginal Microbiome: Why It Matters and How to Support It

When biohacker Bryan Johnson tweeted about his girlfriend's "100 out of 100" vaginal microbiome score, it sparked a cultural moment that Dr. Sarah Saw, a Harvard- and MIT-trained gynecologist, found both important and unsettling. "It felt like a cultural moment," she says, "but also, why is his diary now including the most intimate details about her?" The episode navigates this tension—between the genuine need to talk about vaginal health and the risk of turning it into another metric for women to optimize and be shamed by.

The Key Defender: Lactobacillus Crispatus

The vaginal microbiome operates on a fundamentally different principle than the gut microbiome. In the gut, diversity is the goal—you want many different bacterial species. In the vagina, the opposite is true. Diversity is actually associated with disease. What you want is dominance by a single bacterial species: Lactobacillus crispatus.

Dr. Saw calls it "the bouncer" and "immune modulator" of the vagina. Women whose vaginal microbiome is dominated by L. crispatus have lower rates of bacterial vaginosis, yeast infections, sexually transmitted infections, and preterm birth during pregnancy. When L. crispatus is not dominant, women become more vulnerable to these problems.

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What you'll learn

1 (00:00) **The Brian Johnson "Coochie Carfax" Moment** - Dr. Sarah Saw reacts to the biohacker tweeting his girlfriend's vaginal microbiome score and explains why the moment is both culturally important and deeply creepy.
2 (02:30) **Lactobacillus Crispatus: The Vagina's Bouncer** - Dr. Saw explains the single most important bacterial species for vaginal health and why it differs from the gut microbiome.
3 (09:59) **New Partners, Semen, and the pH Problem** - Dr. Saw explains why a new sexual partner can trigger yeast infections, UTIs, or BV.
4 (13:06) **Two Truths and a Lie: Washing, Perimenopause, and "Top 1%"** - Dr. Saw plays a game to bust three common myths about vaginal care.
5 (14:20) **How (and How Not) to Wash Your Vulva** - Dr. Saw gives a practical, shame-free guide to hygiene.
6 (18:56) **What a Healthy Vagina Smells Like (and What It Shouldn't)** - Dr. Saw decodes vaginal odors so listeners can distinguish normal from problematic.
7 (23:00) **Myth or Fact: PH Washes, Scented Tampons, and Period Panties** - Dr. Saw rates common products and practices.

+ Full timestamped outline available in the app

Show Notes

What’s the vaginal microbiome? How do we know if it’s healthy? In this episode, I asked a Harvard and MIT trained Gynecologist these vaginal microbiome questions + the questions you’ve been too embarrassed to say out loud about your own vagina.

My guest is Dr. Sara Szal, a board-certified gynecologist and functional medicine practitioner with 30 years of clinical experience. She is one of the most prominent voices at the intersection of hormones, the vaginal microbiome, and women’s health. We get into every question you’ve ever had that’s related to your vaginal health.

🎧 What you’ll learn:

• If your vaginal microbiome matters more than your gut microbiome

• How sex, new partners, and semen affect your vaginal health

• Antibiotics, tampons, and tight leggings affect on your vagina

• How to properly clean down there in a safe way

• What vaginal smells are healthy and what are not

• If hormone replacement therapy is for everyone

• The breast cancer risk factor people don’t talk about enough

To assess your lifetime risk of breast cancer, take the Tyrer-Cuzick Risk Assessment Quiz Dr. Sara Szal recommended.

For more from Dr. Sara Szal:

• Substack: https://saraszalmd.substack.com/

• Website: https://saraszalmd.com/

• Books: https://saraszalmd.com/books/

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