Skin

How the Gut Shows Up on the Skin

Skin and gut look like separate problems. They aren't, for two reasons. Both are barriers, built to keep the outside out, and both are maintained by the same immune signalling. And the skin is where systemic inflammation becomes visible, so a rise in inflammatory signalling that would otherwise go unnoticed shows up as a rash, a flare or a patch that won't settle. That's why so many skin conditions have turned out to have measurable gut findings behind them.

What the trials have found

Eczema has the largest evidence base. A meta-analysis of 8 trials covering more than 2,500 infants found probiotics given during pregnancy and early life reduced the risk of childhood eczema by 14%. That's a modest effect, but it concerns preventing a condition rather than treating one.

Psoriasis has been tested repeatedly. A meta-analysis of 15 trials found probiotics improved severity scores, in some comparisons more than pharmaceutical treatments used as the comparator.

Acne has smaller but rigorous evidence. A meta-analysis of 3 double-blind randomised trials found oral probiotics genuinely reduced inflammatory lesions, with a modest effect size.

Rosacea produced the most striking single result. Treating small intestinal bacterial overgrowth, meaning an abnormally large bacterial population in a part of the gut that should stay sparse, cleared rosacea completely in most patients in one trial, and the effect held for at least nine months.

Chronic hives were tested in a randomised trial of more than 200 children, where a probiotic added to standard treatment significantly reduced both the size of the hives and how often they flared.

Not everything works. A rigorous meta-analysis of oral supplements for skin hydration found no benefit from lactic acid bacteria specifically, unlike several other supplements tested alongside them.

Source: Association of Probiotics with Atopic Dermatitis among Infant: A Meta-analysis of Randomized Controlled Trials

Source: The gut-skin axis in psoriasis: Evidence-based insights from a meta-analysis on probiotics and synbiotics

Source: Small Intestinal Bacterial Overgrowth in Rosacea: Clinical Effectiveness of Its Eradication

What this means for you

Persistent or worsening skin conditions need proper assessment, since prescribed treatments for eczema, psoriasis and acne work well and untreated moderate acne can scar permanently. In addition, the research above found trial evidence for gut-focused approaches across several separate skin conditions, alongside at least one clear negative result worth knowing about. A varied, plant-rich diet supports the same gut bacteria this research ties to calmer skin inflammation and a better maintained barrier. That's the same idea behind GutLab, everyday gut health starts with regularly feeding the microbiome a broad range of plant-rich ingredients.

Explore skin conditions on this page

The panels on this page cover conditions where the gut connection has been tested rather than assumed, and the strength varies considerably.

Eczema, psoriasis, acne and rosacea have the most developed evidence, in each case from randomised trials or meta-analyses of them. Hives and dermatitis have smaller trials behind them.

Wound healing, skin ageing, dry skin and rashes are earlier work, and dry skin is the one where the rigorous evidence came back negative.

Use the panels on this page to find the one relevant to you.