Dermatology · Nutrition · Research Digest
Can What You Eat Change Your Skin? What the Evidence Actually Says About Popular Diets and Skin Conditions
From the ketogenic diet to elimination protocols, patients and clinicians alike are asking whether food choices can treat — or worsen — conditions like acne, psoriasis, eczema, and skin cancer. A new narrative review from Northwestern University cuts through the noise.
📅 January/February 2025 · The Dermatology Digest
✍️ Moraga & Lio · Northwestern University Feinberg School of Medicine
⏱ 9 min read
45%
Of Americans who commit to healthier eating habits each January
6
Popular diet trends reviewed for their dermatological impact
72%
Relative reduction in basal cell carcinoma odds with Mediterranean diet adherence
5
Skin conditions reviewed — acne, psoriasis, HS, eczema, and skin cancer
Every January, millions of people overhaul their diets with one hope in mind: to feel better, look better, and live longer. Increasingly, “look better” has come to include the skin — and dermatology patients routinely arrive at appointments asking whether cutting carbs, going keto, or following a Mediterranean diet might help their acne, psoriasis, or eczema. Until now, most clinicians had little consolidated evidence to draw on when answering. A new narrative review aims to change that.
Published in The Dermatology Digest, this review from researchers at Northwestern University and Rosalind Franklin University of Medicine systematically examines six of the most popular diet trends — from ketogenic to low-fat — and evaluates their evidence base across five major dermatological conditions. The findings are nuanced, sometimes surprising, and carry an important caution: the connections between diet and skin are real, but they are not yet simple.
One Important Caveat Before We Begin
The authors open with a critical methodological warning that applies to almost every study reviewed. Weight loss by itself powerfully reduces inflammation — meaning that when a diet improves a skin condition, it is often very difficult to determine whether the improvement came from the specific dietary changes or simply from losing weight. This is not a minor caveat. It fundamentally complicates the interpretation of almost all diet-skin research and is one reason the field has progressed more slowly than patients might hope.
⚠ The Weight Loss Confound — Why Diet Research Is Harder Than It Looks
Most diets produce weight loss, and weight loss reduces inflammation independently of what was eaten. Separating the specific effects of a particular dietary pattern from the general effects of losing weight is inherently difficult — and many studies in this field have not managed to do it cleanly. Keep this in mind when evaluating any diet-skin claim.
Diet by Diet: What the Evidence Shows
The ketogenic diet — originally developed as a treatment for epilepsy — works by drastically reducing carbohydrate intake, forcing the body to burn fat for fuel instead of glucose. This state of nutritional ketosis has been found to improve inflammatory and metabolic markers alongside aiding weight management.
Psoriasis
RCT (n=26) — Lambadiari et al., 2024
In a head-to-head randomised trial against the Mediterranean diet, patients on the KD for 8 weeks showed a significant reduction in the Psoriasis Area and Severity Index (PASI) (P = 0.04) — achieving twice the PASI reduction of the Mediterranean diet group. Psoriatic arthritis activity (DAPSA) fell by 98.62% vs. 32.64% on the Mediterranean diet (P = 0.034). However, both groups also lost significant weight, making it impossible to attribute the improvement to the diet alone.
Acne
Observational study (n=31 women) — Verde et al., 2024
Women with acne and grade I obesity placed on a ketogenic diet for 45 days showed significant reductions in Global Acne Grading System scores (−31.46%, P < 0.001) and improvements in quality of life (DLQI −45.44%, P < 0.001). The authors attributed this to the diet’s anti-inflammatory and antioxidant effects — but the absence of a control group and small sample size limit the conclusions that can be drawn.
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Verdict: Promising but preliminary. Early results are encouraging for both psoriasis and acne, but studies are small and it remains unclear whether benefits come from the diet specifically or from weight loss. More RCTs at scale are urgently needed.
The Paleolithic diet encourages eating foods similar to what our pre-agricultural ancestors consumed — lean meats, fish, fruits, vegetables, nuts and seeds — while eliminating processed foods, grains, dairy, and refined sugar. It has grown in popularity particularly among younger generations and those with metabolic conditions.
Acne
Observational study (n=1,200) — Cordain et al., 2002
Researchers visited every house in Kitava, Papua New Guinea — a population whose diet closely mimics Paleolithic eating — examining 1,200 patients aged 10 and over for acne. The result was striking: not a single pustule, papule, or comedone was observed in the entire cohort. Dairy, coffee, salt, sugar, and alcohol consumption were minimal, and carbohydrates came primarily from low-glycemic fruits and vegetables. While purely observational, this finding is difficult to ignore.
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Verdict: Intriguing observational signal, no RCT evidence. The Kitava study is compelling, but no randomised controlled trials exist examining the Paleolithic diet and skin conditions. The higher meat consumption, absence of grains and dairy, and increased grocery costs also raise practical concerns.
The Mediterranean diet (MD) is one of the world’s most studied dietary patterns, characterised by extra-virgin olive oil, legumes, cereals, nuts, fruits, vegetables, and fish. The DASH diet (Dietary Approaches to Stop Hypertension) was originally designed to lower blood pressure, and is recommended by the USDA as one of the healthiest overall eating plans. Both emphasise plant-rich, anti-inflammatory eating with reduced processed foods.
Skin Cancer
RCT (n=505) — Leone et al., 2020
In a nested case-control study, adherence to the Mediterranean diet was associated with a 72% relative reduction in the odds of basal cell carcinoma (BCC) (OR: 0.28; 95% CI: 0.10, 0.77). The DASH diet showed a 68% relative risk reduction (OR: 0.32; 95% CI: 0.14, 0.76). Researchers speculated that higher consumption of fruit and low-fat dairy products may be responsible for this protective effect.
Hidradenitis Suppurativa
Cross-sectional study (n=221) — Lorite-Fuentes et al., 2022
Higher adherence to the Mediterranean diet was associated with significantly lower hidradenitis suppurativa (HS) severity scores (IHS4, β = −0.10, P < 0.001). This association held after adjusting for disease duration, age, and physical activity levels (β = −0.04, P = 0.03). The researchers pointed to extra-virgin olive oil as the likely key culprit — or remedy — given its known anti-inflammatory properties. However, the cross-sectional design prevents causal conclusions.
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Verdict: Strongest overall evidence base. The Mediterranean diet has the most consistent and compelling evidence across skin conditions, particularly for skin cancer risk reduction and hidradenitis suppurativa severity. This is also the most broadly health-promoting of all diets reviewed.
A low-glycemic load diet goes beyond the glycemic index by factoring in both how quickly a food raises blood sugar AND how much carbohydrate it contains per serving. The key dermatological connection: high-glycemic diets increase insulin and insulin-like growth factor 1 (IGF-1) activity — both of which are thought to stimulate the biological processes that drive acne development. This also explains why metformin, a diabetes medication, shows promise in acne treatment.
Acne (RCT 1)
RCT (n=43 males) — Smith et al., 2007 (Australia)
After a 12-week low-glycemic load dietary intervention, total acne lesion counts fell significantly more in the LGL group (−23.5 ± 3.9) than in the control group (−12.0 ± 3.5) (P = 0.03). The LGL diet focused on 25% protein energy and 45% from low-GI carbohydrates. However, the authors could not isolate the dietary effect from general weight loss.
Acne (RCT 2)
RCT (n=32 patients) — Kwon et al., 2012 (Korea)
A 10-week LGL intervention significantly reduced both inflammatory and non-inflammatory acne lesions (R² = 0.35, P < 0.01). Crucially, skin biopsies from the LGL group showed significantly reduced inflammation and smaller sebaceous glands — and there were no significant changes in BMI or total caloric intake in either group. This is important because it suggests the improvement was due to the diet itself, not weight loss — addressing the key confound that limits most other studies.
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Verdict: Good evidence for acne specifically. Two RCTs support the LGL diet’s benefit for acne, and the Kwon study’s histopathological evidence and weight-stability finding give it notable credibility. For acne patients, a low-glycemic diet is one of the most evidence-backed dietary recommendations available.
An elimination diet removes one or more food groups or specific ingredients from the diet — the exact protocol varies depending on the presenting condition. These diets often require a multidisciplinary team including allergists, gastroenterologists, and nutritionists. They have established efficacy in conditions such as eosinophilic esophagitis and migraine. In dermatology, the evidence is more limited but promising in specific contexts.
Hidradenitis Suppurativa
Prospective study (n=20) — Colboc et al., 2016
A brewer’s yeast exclusion diet (removing bread, pizza, pastries, beer, wine, and fermented cheese) produced significant improvements after just 3 months: reduced pain (P = 0.006), fewer HS-impaired days per month (P = 0.007), reduced inflammation intensity (P = 0.018), and reduced discharge (P = 0.005). A smaller study (n=12) found that surgical excision combined with yeast exclusion produced complete HS regression within one year — with recurrence upon reintroduction of beer or wheat.
Atopic Dermatitis
Systematic review (10 RCTs) — Oykhman et al., 2022
Dietary elimination may produce slight improvements in pruritus, eczema, and sleep disruption in patients with mild to moderate atopic dermatitis. However, the authors cautioned strongly against relying on elimination diets over more effective established treatments, and flagged an increased risk of IgE-mediated food allergy in AD patients who eliminate foods.
Atopic Dermatitis
RCT (n=50) — Worm et al., 2000 (Low-Pseudoallergen Diet)
A low-pseudoallergen diet (removing food coloring, preservatives, histamine, and nitric oxide) led to a 57% improvement in AD severity in 26 of 41 completing patients, alongside a 52% average reduction in serum eosinophilic cationic protein levels. 19 of 24 patients re-exposed to pseudoallergens experienced eczema worsening.
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Verdict: Condition-specific and variable. Promising for HS (particularly yeast exclusion) and a useful adjunct for some AD patients. But elimination diets carry real risks including nutritional deficiencies, increased food sensitisation, and are not recommended as primary treatment for most conditions.
A low-fat diet restricts fat intake to 20% or fewer of total daily calories. The evidence in dermatology produces a genuinely contradictory picture — depending on the population studied and the duration of the intervention, findings point in opposite directions.
Skin Cancer (Study 1)
RCT (n=115) — Black et al., 1995
Over a 2-year period, patients on a low-fat diet (reducing fat to 21% of calories) showed a significant decline in non-melanoma skin cancer (NMSC) incidence by the final 8-month period (P < 0.05). Crucially, there were no significant differences in total daily calories or mean body weight between groups — suggesting the effect was attributable to the dietary fat reduction itself rather than to weight loss.
Skin Cancer (Study 2)
RCT (n=48,835 postmenopausal women) — Gamba et al., 2013
In a much larger, longer trial spanning more than 8 years, a low-fat diet did not affect overall NMSC incidence (HR 0.98, 95% CI: 0.92–1.04) or melanoma incidence (HR 1.04, 95% CI: 0.82–1.32) in postmenopausal women. The enormous sample size and long duration make this a very credible null finding.
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Verdict: Conflicting evidence — no clear recommendation possible. A small 2-year trial suggested benefit for skin cancer, but a far larger 8-year trial found no effect. The discrepancy may reflect differences in population, duration, or methodology. More research is needed before any confident clinical guidance can be offered.
Summary: All Six Diets at a Glance
| Diet |
Skin Condition(s) |
Evidence Quality |
Overall Signal |
| Ketogenic |
Psoriasis, Acne |
1 RCT + 1 observational study |
Promising / Limited |
| Paleolithic |
Acne |
Observational only — no RCTs |
Intriguing / No RCT |
| Mediterranean |
Skin cancer (BCC), Hidradenitis suppurativa |
1 RCT + 1 cross-sectional study |
Strongest Evidence |
| DASH |
Skin cancer (BCC) |
1 RCT |
Positive Signal |
| Low-Glycemic Load |
Acne |
2 RCTs with histopathological data |
Good for Acne |
| Elimination |
Hidradenitis suppurativa, Atopic dermatitis |
Mix of RCTs, observational studies, and meta-analysis |
Variable / Condition-Specific |
| Low-Fat |
Skin cancer (NMSC) |
2 RCTs with conflicting results |
Conflicting |
What Dermatologists Should Take Away
The review’s authors are careful not to overstate any single finding. Diet-skin research is genuinely difficult to conduct rigorously — blinding patients to their dietary assignment is often impossible, compliance is hard to verify, and separating dietary effects from weight-loss effects requires study designs that are expensive and hard to sustain over long periods.
That said, the review points to some actionable clinical directions:
Practical Takeaways for Clinicians and Patients
- For acne patients: A low-glycemic load diet has the strongest and most consistent evidence — supported by two RCTs, including one with histopathological confirmation and no weight-change confound. This is a reasonable first-line dietary recommendation.
- For psoriasis and HS patients: The Mediterranean diet has meaningful evidence for both skin cancer risk and HS severity. It is also broadly anti-inflammatory and carries no meaningful health risks — making it a safe and evidence-informed recommendation.
- For HS patients specifically: Brewer’s yeast exclusion shows interesting preliminary results and may be worth discussing with motivated patients as an adjunct to established treatment.
- For patients asking about ketogenic or Paleolithic diets: The evidence is not yet strong enough to recommend these specifically for skin conditions, though both may help through general anti-inflammatory and weight-loss effects.
- Be cautious about elimination diets for eczema: The evidence supports only modest benefit, and these diets carry real risks including food sensitisation and nutritional deficiencies — particularly in children and pregnant women.
- Always address orthorexia risk: An obsessive focus on dietary perfection can become harmful in itself, and may divert patients from pharmacological or other proven treatments that genuinely work.
Key Takeaways from the Review
- Diet does affect skin — but the links are complex: Evidence exists for multiple diets across multiple conditions, but most studies are small, short, and confounded by weight loss effects
- The Mediterranean diet has the strongest evidence base: Associated with up to 72% reduced odds of basal cell carcinoma and significantly lower hidradenitis suppurativa severity — with no downside risk
- Low-glycemic load diets are the best-supported intervention for acne: Two RCTs, including one with tissue-level evidence and no BMI change, make this the most credible dietary recommendation for acne patients
- Ketogenic diets show early promise for psoriasis and acne: But studies are small and confounded by weight loss — more large-scale RCTs are urgently needed before firm recommendations can be made
- Elimination diets are condition-specific and require caution: Useful as adjuncts in HS and some AD cases, but carry risks of nutritional deficiency and increased food sensitisation
- Weight loss matters independently: No matter which diet a patient follows, losing weight reduces systemic inflammation — and this effect alone may explain many of the skin improvements seen across all dietary patterns
The role of diet in dermatology is real, underexplored, and evolving. For clinicians, the message is to stay informed, set realistic patient expectations, and prioritise diets with the broadest health evidence — like the Mediterranean diet — while awaiting more definitive skin-specific data.
Source: Moraga R, Lio PA. “Popular Diet Trends in Dermatology: A Narrative Review.” The Dermatology Digest / The Irregular Border, January/February 2025. Richard Moraga is a medical student at Rosalind Franklin University; Peter A. Lio, MD, is a Clinical Assistant Professor of Dermatology and Pediatrics at Northwestern University Feinberg School of Medicine. This post summarises the review for general audiences. All statistics and study findings are drawn directly from the original article.
