Are Fermented Foods Doing More Harm Than Good?

Fermented foods are often praised as the holy grail of gut health. But if you’re one of the millions struggling with eczema, rosacea, irritable bowel syndrome, headaches or chronic hives, these so-called health foods might be doing more harm than good.

Watch our Nine News report, which was filmed at our Skin Friend HQ, where our nutritionist, Karen Fischer, discussed her latest research. Every parent should see this. 

A new scientific study from Bond University has uncovered a surprising connection between eczema flare-ups and naturally occurring food chemicals—particularly histamines and salicylates, which are found in everyday foods, including fermented products like sauerkraut, soy sauce, kimchi, kefir and kombucha.

Children are particularly at risk because they have under-functioning livers that cannot properly break down food chemicals such as histamine and salicylates. So giving them avocado, especially if they have eczema, could unknowingly trigger a flare up. 

Image: Fermented foods include soy sauce, vinegar, sauerkraut, kimchi, yoghurt and picked foods. 

The Hidden Link Between Fermented Foods and Eczema

Led by Bond University PhD researcher and nutritionist Karen Fischer, the study is the first to systematically review and combine global data on eczema and food intolerance. Published in the peer-reviewed journal Nutrients, the research shows a significantly higher prevalence of eczema among people with documented intolerances to amines (including histamine) and salicylates.

This means that for some people, eating high-histamine foods—like fermented vegetables or probiotic drinks—could be silently triggering or worsening their skin condition.

“Many of my patients were reacting to so-called healthy foods like spinach, avocado and fermented products,” says Karen. “These aren’t allergies—they’re reactions to food chemicals like histamine, which can accumulate in the body and overwhelm the system if not properly broken down.”

Histamine Intolerance: A Common Yet Overlooked Skin Trigger

Histamine is a natural compound involved in the immune response, but too much can cause problems. People with histamine intolerance often lack enough of the enzyme DAO (diamine oxidase), which breaks down histamine in the gut. When histamine builds up, it can lead to a wide range of symptoms—including eczema, flushing, itching, hives, headaches and digestive issues.

Because fermented foods are rich in histamine, they’re one of the first categories eliminated on a low histamine diet—a therapeutic approach that’s gaining traction for skin conditions like eczema (atopic dermatitis), hives (urticaria) and rosacea.

Why Fermented Foods Aren’t Always Safe for Children or Eczema Sufferers

Foods that are high in histamines, amines or salicylates include:

• Fermented foods (sauerkraut, kimchi, kombucha, soy sauce)

• Aged cheese and cured meats

• Avocado, spinach, tomato

• Vinegar, citrus fruits, berries

• Wine and champagne

• Yoghurt and many probiotics

These foods may be tolerated well by the general population, but for those with skin conditions, food intolerances or MCAS (mast cell activation syndrome), they can silently undermine progress.

Should You Quit Fermented Foods?

Not everyone needs to avoid fermented foods—but if you’ve tried every cream and your eczema still flares, or your skin feels inflamed, itchy or unpredictable, it might be time to look deeper. A short-term low histamine and low salicylate diet, such as The Eczema Detox, can help identify if these foods are triggering your symptoms.

“The goal isn’t long-term restriction,” says Karen. “It’s about calming the skin, identifying triggers, and rebuilding a healthier relationship with food.”

For those needing structured support, The Eczema Detox and the Food Intolerance Diagnosis (FID) Program are science-backed approaches that guide you through the process safely and effectively.

The Bottom Line

Fermented foods aren’t bad—but they may not be right for your skin. If you're dealing with stubborn eczema, it’s worth asking: could histamine-rich foods be your hidden trigger?

Explore our resources at skinfriend.com to learn more about low histamine diets, eczema-safe recipes and skin-friendly supplements formulated with science in mind.

Want Natural Support for Eczema?

If you are confused about what to do next and would like guidance from a health professional, start by ordering Karen Fischer's Eczema Detox Clear Skin Toolkit or buy her book The Eczema Detox. It's suitable for children from age 1, to teens and adults. Both show you how to identify your (or your child's) personal food triggers so you know what foods to eat and avoid, and then how to test and incorporate them back into your diet as your skin improves. 

Karen Fischer, lead researcher and founder of Skin Friend, has formulated science-backed skincare and eczema-safe supplements to help support sensitive skin and food intolerances—without steroids or harsh chemicals.

If you’re unable to join the trial, order from Karen's product range to explore her full range of eczema-friendly products.

Click here for Karen’s eczema products. 

Reference: Fischer K, Jones M, O'Neill HM. Prevalence of Intolerance to Amines and Salicylates in Individuals with Atopic Dermatitis: A Systematic Review and Meta-Analysis. Nutrients. 2025 May 9;17(10):1628. doi: 10.3390/nu17101628. PMID: 40431369; PMCID: PMC12114600.