Why This Topic Belongs in Every Derm Visit
Buchi Neita, PA-C, opens by admitting neither she nor her co-host, Shanna Miranti, PA-C, considers themselves experts on the gut-skin axis, but that is exactly the point: patients are increasingly walking in with questions about probiotics, gut microbiome testing, and diet. As Miranti frames it, if you treat conditions like psoriasis, you almost certainly have patients already experimenting with probiotics and at-home microbiome tests, so clinicians need at least a working understanding to stay credible.
The research base is young but expanding fast. Neita notes that a 2016 PubMed search on the gut-skin axis returned roughly eight publications; that number has grown to around 174. She is candid that strong, high-quality data are still limited, but the trajectory suggests this will become more clinically actionable over time.
Both hosts stress a practical reality: if patients raise these questions and get brushed off, they will find another clinician. Miranti advises being comfortable saying "we don't know" while still listening, engaging, and offering evidence-based suggestions.
The Biology: Two Barrier Organs That Talk to Each Other
Neita walks through the structural parallels between skin and gut. Both are primary contact organs, both are first-pass barriers to environmental allergens and irritants, and both rely on tight junctions—the same brick-wall analogy dermatology already uses for skin. When she polled the audience on what the gut-skin axis brings to mind, one attendee shouted "IL-23," which she loved because IL-23 is critical to maintaining those tight junctions.
The communication is bidirectional. Neita cites studies showing that wounding mouse skin significantly altered their gut microbiome, and conversely, modulating gut bacteria improved skin lesions in atopic dermatitis, acne, psoriasis, and rosacea. Impairing one microbiome affects the other.
Gut dysbiosis and 'leaky gut' anchor the concept, alongside the role of short-chain fatty acids. Both hosts point to the fiber-poor Westernized diet as a driver of trouble: digesting fiber produces short-chain fatty acids with meaningful anti-inflammatory effects, and low fiber intake undermines that protective pathway.
Where Cytokine Pathways and IBD Intersect
Miranti reframes a familiar rule—don't give IL-17 inhibitors to psoriasis patients with concomitant IBD—as far more nuanced than 'just avoid them.' IL-23 inhibitors work beautifully for both skin and gut, but IL-17, while pro-inflammatory, is still essential in the gut. Completely suppressing IL-17 can break down intestinal cells and worsen inflammation, so the goal is enough IL-17 to keep the gut healthy, not total shutdown. JAK inhibitors, she explains, calm the relevant cytokines without fully suppressing them, which helps explain their utility across HS, psoriasis, and IBD.
Hidradenitis suppurativa is a disease state the hosts urge listeners not to overlook. Data are thinner than for psoriasis or atopic dermatitis, but HS patients appear to share a gut microbiome signature similar to Crohn's disease, and IBD can co-occur. With IL-17 inhibitors now approved for HS, Miranti says clinicians should screen HS patients for GI symptoms just as they do psoriasis patients.
She shares a concrete workup tip: fecal calprotectin. If a patient reports diarrhea, cramping, or blood in the stool, a level of 50 or below is reassuring against IBD, while levels of 150–200 and above signal high risk for intestinal inflammation—useful for pushing a GI consult to the top of the list and steering away from IL-17 agents while awaiting the gold-standard intestinal biopsy.
A 100-Year-Old Idea With Modern Evidence
Miranti reminds listeners this concept isn't new: back in 1930, dermatologists Stokes and Pillsbury described a gut-skin-brain axis, linking acne to gut inflammation, mood, and lactobacillus supplementation. Nearly a century later, the literature is finally catching up.
On acne, Neita and Miranti cite a small 12-week study with three arms—probiotic alone, oral minocycline alone, and minocycline plus probiotic. All groups improved, but the combination group did significantly better and had far fewer side effects; several minocycline-only patients dropped out due to vaginal candidiasis, while the combination group had none. The takeaway for both hosts is a shift from reactive to proactive probiotic use as adjunct therapy, not monotherapy.
For atopic dermatitis, they note evidence that lactobacillus probiotics given to pregnant women reduce the child's risk of atopic dermatitis, whereas giving probiotics to the infant after birth does not prevent it. They also discuss staph aureus colonization contributing to gut permeability and food allergies, and a study showing narrowband UV phototherapy reduced skin staph counts in psoriasis and subsequently reduced harmful gut microbiota.
Counseling Patients Without Overwhelming Them
Miranti, a diplomate of the American College of Lifestyle Medicine, leans on its six pillars: a whole-food plant-based diet, physical activity, restorative sleep, avoiding risky substances, and social connection. She uses ACLM printed handouts to spell out what a whole-food plant-based diet actually looks like, emphasizing that it doesn't require going vegetarian or vegan; it means adding fiber-rich foods and increasing plant diversity to boost gut diversity. Her rule: assume patients start with no nutrition knowledge and be highly specific.
Both hosts warn about the supplement marketplace. Miranti stresses that probiotic manufacturing is complex—even when a strain has evidence, clinicians can't be sure the bottle contains a legitimate, high-quality, properly stored, reproducible product. She recommends leaning on researchers doing the work rather than marketing claims.
Neita points to the Medeso study (published in JAD, 2025), where psoriasis patients randomized to a Mediterranean diet over 16 weeks showed reduced hemoglobin A1c and improved PASI scores versus dietary counseling alone. She counsels delicately, meeting patients where they are and doling out small tidbits per visit. Both hosts close with real cases—a psoriasis patient who cleared 20% BSA after going vegan, and an acne patient whose disease flared when he returned to a poor diet post-isotretinoin—underscoring that asking the right questions reveals what treatment alone can't.