The gut-skin axis: what to eat

Gut microbes and acne

The gut-skin axis is the two-way link between gut microbes and skin. A 2022 review wrote that numerous studies have shown the bidirectionality between the intestinal microbiota and skin homeostasis, a communication mainly established by modifying the immune system (Sánchez-Pellicer et al., 2022).

A 2024 genetic analysis used Mendelian randomization on gut-microbe and acne data. After checks, Cyanobacterium and Family XIII were risk factors for acne vulgaris, while Ruminococcus1 and Ruminiclostridium5 were protective factors (Wu et al., 2024). That method infers links from genes. It does not test a diet.

The same 2022 review cited a 2001 culture study of 114 acne patients, 94 with papulopustular acne and 20 with nodulocystic acne, in which 54% presented gut dysbiosis. We found no trial that fed people a "gut-skin" plate and measured acne. Redness and calm-skin eating overlap on the anti-inflammatory diet. The American Academy of Dermatology's 2024 acne guidelines found available evidence was insufficient to develop recommendations for dietary changes (AAD, 2024).

Probiotic capsules

A 12-week trial in people aged 12 to 30 found 42.5% of those taking a probiotic capsule improved on an acne grading scale, compared with 20.6% on placebo (Eguren et al., 2024). The capsule held one bacterial strain plus spirulina. Staff from the maker co-wrote the paper.

We still grade the human evidence Limited. A capsule isn't yogurt. Keep eating plants and slower carbs while you try a strain.

Fermented foods

We found no trial that compared yogurt or kimchi with none and measured acne. The closest food trial gave 36 people fermented milk for 12 weeks, with or without added lactoferrin, so both groups had the fermented food (Kim et al., 2010).

A Stanford study of 36 healthy adults put people on a high-fibre or a high-fermented-food diet. Over 10 weeks, the fermented-food group built up from less than one serving a day to about six, of foods like yogurt, kefir, kimchi and kombucha. Gut bacteria grew more diverse, and 19 of 93 inflammatory proteins in blood went down. The study tracked gut and blood, not skin (Wastyk et al., 2021).

Yogurt is also dairy. The yogurt split is on dairy and acne.

Leaky-gut diet

We found no trial of a leaky-gut diet that measured acne. Two blood-marker studies found higher signals of a leakier gut wall in people with acne.

In 77 patients with acne and 77 controls, median serum I-FABP was 32.03 pg/ml against 22.81 pg/ml. I-FABP rose with acne severity, with a Spearman r of 0.797 (Aksoy Saraç et al., 2026).

In 75 people with acne and 75 controls, mean blood zonulin was 195.54 ng/mL against 158.45 ng/mL (Gürel et al., 2025). Those papers measured markers. They did not feed a protocol.

Gut cleanse

We found no trial of a gut cleanse, or of treating SIBO, that measured acne as the outcome we could check. A 2024 dermatology review wrote that reports indicate small intestinal bacterial overgrowth (SIBO) is about 10 times more extensive in those with acne compared to healthy controls (Gowda et al., 2024). That is a review sentence, not a new trial. Do not treat a cleanse as acne care.

Vegetables

In a survey of 2,467 Thai teens and adults, eating vegetables went with milder acne, with an adjusted odds ratio of 0.74 (Roengritthidet et al., 2021). We found no trial that tested vegetables alone for acne. The acne plate is on foods for clear skin.

Low-GI carbs

Glycemic index (GI) is a measure of how quickly a food raises your blood sugar. It runs from 0 to 100. Foods at 55 or below count as low-GI (MedlinePlus).

In a 12-week trial of 43 young men, spots fell by 23.5 on a low-GI diet against 12.0 on a control diet (Smith et al., 2007). In a 2012 trial of 32 people, a low-GI diet for 10 weeks led to fewer spots (Kwon et al., 2012). White bread sits at 75 and white rice at 73 (Atkinson et al., 2008). Among 2,467 Thai teens and adults, white rice went with more severe acne, with an adjusted odds ratio of 1.80 (Roengritthidet et al., 2021). The carb swaps sit on our low-glycemic guide and the bread page.

Oily fish

In 248 young adults in New York, those with moderate-to-severe acne reported more added sugar and a higher dietary GI, and fewer servings of fish a day, than those with none or mild acne (Burris et al., 2014). We found no trial that fed people oily fish and measured acne.

Sugary drinks

In a study of 24,452 French adults, sugary beverages went with 1.18 times the odds of current acne after adjustment (Penso et al., 2020). Among 8,226 Chinese students, daily soft drinks went with moderate-to-severe acne. Sugar from drinks at 100 g a day or more went with 3.12 times the odds (Huang et al., 2019). We found no trial that took sugary drinks out and measured acne. More on sugar and acne.

Cow's milk

A Harvard study of 47,355 women who recalled their high-school diets found those who drank the most skim as teens had a 44% higher rate of severe acne (prevalence ratio 1.44) (Adebamowo et al., 2005). The largest review pooled 14 studies of 78,529 people aged 7 to 30. Any milk 1.28 times the odds; low-fat or skim 1.32 (Juhl et al., 2018). Full story on dairy and acne. Plant milks are a separate question: does oat milk cause acne?

How long to give a swap

We found no trial of one food that reported a pimple clock. The probiotic capsule trial ran 12 weeks (Eguren et al., 2024). Acne diet trials ran 12 weeks in 43 young men (Smith et al., 2007) and 10 weeks in 32 people (Kwon et al., 2012). The American Academy of Dermatology says a treatment that works should show some improvement in 4 to 6 weeks, and clearing can take two to three months or longer (AAD, 2023). Track meals against your own skin with the acne food tracker.