Histamine, not gluten — rethinking the eczema elimination diet

When someone with eczema decides to try dietary changes, gluten is usually the first thing to go. The problem is that for most adults with eczema, gluten isn't the driver. And while people are cutting sourdough and pasta, they're often continuing to eat the foods most likely to be causing their flares.

Why gluten gets the blame

Coeliac disease — genuine autoimmune intolerance to gluten — does have dermatological manifestations. But dermatitis herpetiformis, the skin condition caused by gluten in coeliac patients, is not eczema. The evidence linking non-coeliac gluten sensitivity specifically to eczema flares is weak. If you've cut gluten for three months and your eczema hasn't changed, this is almost certainly why.

What histamine actually is

Histamine is found in significant quantities in many foods, and in people with reduced capacity to break it down, dietary histamine accumulates and triggers an inflammatory response that can manifest as skin symptoms. The enzyme responsible for breaking down histamine in the gut is diamine oxidase (DAO). Some people produce insufficient DAO — due to genetic variation, gut inflammation, or certain medications — and struggle to process high-histamine foods.

High-histamine foods to watch

The foods highest in histamine are often considered healthy: aged cheese, red wine, cured meats, tinned fish, fermented foods like sauerkraut and kimchi, vinegar, and certain vegetables including tomatoes, spinach, and aubergine. Many people with eczema who eat "clean" diets consume large amounts of these foods — fermented foods in particular are heavily promoted for gut health, without the caveat that they're among the highest-histamine foods available.

The four-week trial

A structured low-histamine elimination diet for four weeks, followed by a controlled reintroduction phase, can be diagnostic in itself. If symptoms improve significantly during the elimination phase, histamine intolerance is likely a contributing factor.

Other dietary factors worth investigating

Beyond histamine, nickel sensitivity and salicylate sensitivity are worth examining if a low-histamine trial produces only partial improvement. True IgE-mediated food allergies — where the immune system produces antibodies against a specific food protein — do cause eczema flares, and the appropriate test is a skin prick test or specific IgE blood test arranged through a GP or allergist.