Skin Conditions: The Gut-Skin Axis Approach

The Skin as Mirror

Your skin is not a wrapper. It is a 22-square-foot organ — the largest in your body — and it talks. Every rash, every flare, every patch of redness is a sentence in a language most dermatologists never learned to read. They see the sentence and try to silence it with steroids. Functional medicine reads the sentence and asks: what is the body trying to say?

The answer almost always comes from inside.

Hippocrates said “all disease begins in the gut.” Twenty-four centuries later, the research caught up. The gut-skin axis is now one of the most well-documented bidirectional communication systems in the body. Gut dysbiosis increases intestinal permeability. Bacterial endotoxins (lipopolysaccharides) cross into the bloodstream. The immune system activates. Systemic inflammation rises. And the skin — richly vascularized, densely innervated, teeming with its own microbiome — becomes the canvas where that internal fire paints itself.

The numbers are striking: 34% of IBS patients have skin manifestations. SIBO is 10 times more common in rosacea patients than in controls (Parodi 2008). Celiac disease presents with dermatitis herpetiformis before any GI symptom in many patients. Psoriasis patients have significantly higher rates of metabolic syndrome, fatty liver, and cardiovascular disease. The skin is downstream. Always.

Eczema (Atopic Dermatitis): The Barrier Breakdown

Eczema is a Th2-dominant immune response — the same arm of immunity that fights parasites and drives allergies. The skin barrier is impaired, often due to filaggrin gene mutations (carried by 30-50% of eczema patients), which compromise the “brick and mortar” structure of the epidermis. But genetics loads the gun; environment pulls the trigger. And the environment that matters most is the gut.

Testing

• Food sensitivity panel: IgG and IgE. Dairy and eggs are the top triggers in pediatric eczema — remove them before anything else.
• GI-MAP: Dysbiosis markers, pathogenic bacteria, yeast overgrowth, secretory IgA, pancreatic elastase, calprotectin.
• Stool calprotectin: Gut inflammation marker.
• Zonulin: Intestinal permeability marker.
• IgE panel: Total and specific — environmental and food allergens.
• Vitamin D: Almost always low in eczema patients.

Protocol

Diet: Elimination diet removing dairy, eggs, gluten, and soy as the top four triggers. Maintain for 4-6 weeks, then systematic reintroduction every 3-4 days. In children, dairy alone resolves eczema in a remarkable percentage of cases.

Gut healing — the 5R framework:

1. Remove triggers (food sensitivities, infections, irritants)
2. Replace (digestive enzymes, HCl if needed)
3. Reinoculate (probiotics, prebiotics)
4. Repair (L-glutamine, zinc carnosine, aloe, DGL)
5. Rebalance (sleep, stress, lifestyle)

Probiotics: Lactobacillus rhamnosus GG — the most studied probiotic in pediatric eczema prevention and treatment. Multiple RCTs confirm it reduces eczema severity scores (SCORAD). Bifidobacterium lactis supports Th1/Th2 rebalancing. Dose: 10-20 billion CFU/day.

Key supplements:

• Omega-3 (EPA+DHA): 3g/day — anti-inflammatory, resolvin production
• Vitamin D: 5000 IU/day adults, 1000-2000 IU children (target 50-70 ng/mL)
• Zinc: 30mg/day (immune modulation, skin repair, anti-inflammatory)
• Quercetin: 500mg 2x/day (mast cell stabilizer — reduces histamine release)
• Evening primrose oil (GLA): 500mg 2x/day — GLA is a precursor to anti-inflammatory prostaglandins. Eczema patients often have impaired delta-6-desaturase, the enzyme that converts linoleic acid to GLA. Supplementing bypasses this bottleneck.

Topical: Coconut oil (contains lauric acid — antimicrobial against Staph aureus, which colonizes 90% of eczema skin), colloidal oatmeal (beta-glucan soothes inflammation), tallow balm (mimics human sebum), calendula (wound healing), manuka honey (antimicrobial and promotes tissue repair).

Avoid: Long-term topical steroids (skin thinning, rebound flares, HPA axis suppression), sodium lauryl sulfate (SLS) in soaps and shampoos (strips skin barrier), synthetic fragrances (contact sensitizers), fabric softeners.

Psoriasis: The Autoimmune Fire

Psoriasis is not eczema with thicker scales. It is a fundamentally different beast — a Th17/IL-17-driven autoimmune condition with systemic implications that extend far beyond the skin. Psoriasis patients have 2x the cardiovascular risk, 2x the diabetes risk, and significantly higher rates of fatty liver disease and depression. The average psoriasis patient dies 3-5 years earlier than the general population, mostly from cardiovascular events.

The skin is literally the least of it.

Testing

• Full autoimmune panel: ANA, anti-dsDNA, RF, anti-CCP (psoriatic arthritis screen)
• Fasting insulin, glucose, HOMA-IR (metabolic syndrome is the shadow)
• Full lipid panel with Lp(a) and ApoB
• hs-CRP (systemic inflammation marker)
• Vitamin D (almost universally low)
• GI-MAP (look for streptococcal overgrowth — strep pharyngitis triggers guttate psoriasis through molecular mimicry)
• Liver function tests (psoriasis is linked to hepatic congestion)

Protocol

Diet: Autoimmune Protocol (AIP) or strict elimination diet. Remove gluten, dairy, nightshades (tomatoes, peppers, potatoes, eggplant — contain solanine which can drive inflammation in susceptible individuals), alcohol (especially beer — worsens psoriasis significantly), processed sugar. Anti-inflammatory Mediterranean template as the base.

Key interventions:

• Vitamin D: High-dose targeting 60-80 ng/mL. Some practitioners use Coimbra protocol (high-dose vitamin D 40,000-200,000 IU/day under strict medical supervision with calcium restriction and monitoring — not a DIY approach, but the results in autoimmune conditions are remarkable).
• Omega-3: 4g/day EPA+DHA (higher doses needed for psoriasis than eczema due to the autoimmune component)
• Curcumin: 2g/day with piperine or as a phytosomal form for absorption. Curcumin directly inhibits NF-kB — the master inflammatory switch that drives psoriatic gene expression.
• Milk thistle (silymarin): 200-400mg/day. Liver support — psoriasis has a strong hepatic connection. The liver processes and clears inflammatory cytokines. When the liver is congested, those cytokines recirculate.
• Berberine: 500mg 2-3x/day if there is a metabolic component (insulin resistance, elevated lipids). Addresses the metabolic syndrome that shadows psoriasis.
• Low-dose naltrexone (LDN): 4.5mg at bedtime. Upregulates endorphin and OGF/OGFr signaling, modulates immune response. Multiple case reports and small studies in psoriasis.

Topical: Vitamin D analog (calcipotriol — prescription, slows keratinocyte proliferation), aloe vera gel (anti-inflammatory, studied for psoriasis), Oregon grape (Mahonia aquifolium) cream — contains berberine and has been specifically studied for plaque psoriasis with positive results (Bernstein 2006). Dead Sea salt baths (high magnesium and bromine content).

Acne (Adult): The Hormonal-Metabolic-Gut Triangle

Adult acne is not a skin problem. Say it again. It is a hormonal problem, a metabolic problem, and a gut problem that happens to express itself through sebaceous glands. Every teenager gets told they’ll outgrow it. When you are 35 and still breaking out, the conversation changes — or it should.

The Three Drivers

Insulin: Insulin drives IGF-1, which increases sebum production and keratinocyte proliferation (clogged pores). High-glycemic diets = more acne. This is not controversial — it is textbook.

Androgens: Testosterone and DHEA-S stimulate sebaceous glands. In women, this often tracks with PCOS, where insulin resistance drives ovarian androgen production. The acne-PCOS-insulin resistance triangle.

Gut: Dysbiosis, SIBO, and yeast overgrowth (Candida) all contribute through systemic inflammation, impaired detoxification of hormones (estrobolome), and direct immune activation.

Testing

Fasting insulin, glucose, HbA1c. Testosterone (total and free), DHEA-S, SHBG, IGF-1. Progesterone Day 21 (luteal phase). GI-MAP. OAT (yeast markers: arabinose, tartaric acid). Vitamin D. Zinc.

Protocol

• Insulin resistance: Inositol (myo-inositol 4g/day) for PCOS-driven acne — restores ovarian insulin sensitivity, lowers androgens. Berberine 500mg 2x/day as an alternative or complement.
• Zinc: 30-50mg/day. Anti-androgenic, anti-inflammatory, accelerates wound healing. Brandt 2001 showed zinc comparable to minocycline for inflammatory acne, without the antibiotic resistance.
• DIM (diindolylmethane): 200mg/day. Promotes healthy estrogen metabolism — shifts from 16-OH estrone (proliferative) to 2-OH estrone (protective).
• Omega-3: 2-3g/day EPA+DHA.
• Probiotics: L. rhamnosus, L. acidophilus — gut barrier support, immune modulation.
• Vitamin A (retinol): 5,000-10,000 IU/day — supports keratinocyte turnover, reduces sebum. Not to be confused with beta-carotene, which converts poorly.
• Dietary: Reduce dairy (A1 casein stimulates IGF-1 and increases sebum production), remove sugar and refined carbohydrates (insulin → androgen pathway), spearmint tea 2 cups/day (anti-androgenic in women — Grant 2010).

Topical: Niacinamide 4% serum (anti-inflammatory, reduces sebum, improves skin barrier), tea tree oil 5% (antimicrobial against Cutibacterium acnes — comparable to 5% benzoyl peroxide with fewer side effects), retinoid (tretinoin or adapalene — normalizes keratinization), azelaic acid 15-20% (antimicrobial, anti-inflammatory, inhibits tyrosinase for post-inflammatory hyperpigmentation).

Rosacea: The SIBO Connection

Rosacea is not blushing that got out of hand. It is an innate immune dysfunction involving abnormal cathelicidin (LL-37) antimicrobial peptide processing, Demodex mite overgrowth (these microscopic arachnids live in hair follicles — everyone has some, rosacea patients have 5-10x more), and — critically — small intestinal bacterial overgrowth.

Parodi et al. (2008) found SIBO in 46% of rosacea patients versus 5% of controls. When they treated the SIBO, rosacea improved or resolved in over 70% of cases. This is not subtle. When you treat the gut, the face clears.

Protocol

• Treat SIBO: Rifaximin 550mg 3x/day for 14 days, or herbal antimicrobials (allicin, berberine, oregano oil, neem — the Johns Hopkins study showed herbal protocols comparable to rifaximin)
• Low-FODMAP diet during SIBO treatment (starve the bacterial overgrowth)
• Digestive enzymes with meals
• Betaine HCl: Rosacea patients often have low stomach acid (hypochlorhydria). Low acid → poor protein digestion → bacterial overgrowth in the small intestine → rosacea. The irony: acid-suppressing medications (PPIs) worsen rosacea.
• Probiotics: After SIBO clearance — Saccharomyces boulardii, Lactobacillus species
• Zinc: 30mg/day
• Omega-3: 2g/day

Topical: Metronidazole (anti-inflammatory), ivermectin cream (kills Demodex mites — the most effective topical for papulopustular rosacea), azelaic acid (anti-inflammatory, kills C. acnes), green tea extract (reduces erythema).

Universal Skin Support: The Foundation

Regardless of the specific condition, certain fundamentals support skin health at every level:

• Collagen peptides: 10-20g/day (Types I and III). Provides the raw amino acids (glycine, proline, hydroxyproline) for dermal collagen synthesis. Multiple RCTs show improved skin elasticity and hydration.
• Vitamin C: 1g/day minimum. Essential cofactor for prolyl and lysyl hydroxylase — the enzymes that cross-link collagen. Without vitamin C, collagen cannot form properly (this is literally what scurvy is).
• Silica: 10-20mg/day (from bamboo extract or horsetail). Structural mineral for connective tissue.
• Biotin: 2500-5000mcg/day (supports keratin production).
• Adequate protein: 1g per pound of ideal body weight. Your skin is built from amino acids. You cannot build a house without bricks.
• Hydration: Half your body weight in ounces of filtered water daily. Dehydrated skin is compromised skin.
• Sleep: 7-9 hours. Growth hormone — released during deep sleep — drives skin cell repair and turnover. Chronic sleep deprivation measurably accelerates skin aging.
• Stress management: Cortisol damages the skin barrier, increases sebum production, suppresses wound healing, and drives mast cell degranulation (histamine release). Every skin condition worsens under stress. Meditation, breathwork, nature exposure, vagal toning.
• Clean skincare: Use EWG Skin Deep database to evaluate products. Your skin absorbs what you put on it. The average woman applies 168 chemicals to her skin daily through personal care products. Reduce the toxic load.

The skin remembers everything the body experiences. Feed it from the inside, protect it from the outside, and it will tell a different story.