Histamine intolerance: When food makes you ill

Dr. Charalampos Romanos · April 14, 2026 · 5 min read

Histamine intolerance is an underestimated condition that troubles many people without them knowing the true cause. In my practice, I increasingly find that patients with mysterious headaches, skin problems, and digestive disorders actually have a histamine problem.

What is histamine and where does it come from?

Histamine is a messenger molecule found in many foods, especially fermented foods (cheese, sausage, sauerkraut), aged meat, nuts, and some fish. A system in our body (the DAO enzyme) breaks down histamine. In many people, this system does not work optimally.

Symptoms of histamine intolerance

Headaches, urticaria, itching, gastrointestinal problems, diarrhoea, nausea, bloating, dizziness, and sleep problems are typical. Symptoms often occur after eating histamine-rich foods, but can also occur with a time delay.

DAO deficiency and diagnosis

The DAO enzyme breaks down histamine in the intestinal wall. DAO deficiency leads to histamine intolerance. I test DAO activity and histamine levels to make an accurate diagnosis. This is part of my approach in functional medicine.

Other factors that worsen histamine intolerance

Vitamin B6 deficiency, magnesium deficiency, copper excess, stress, and certain medications can inhibit DAO activity. That's why I conduct thorough nutrient testing.

Dietary approach and foods

A low-histamine diet is the main therapy. Fresh foods, quickly frozen meat and fish, and avoidance of fermented products are central. I create customised plans that ensure adequate nutrients.

Long-term strategies and nutrient optimisation

Not just diet, but also nutrients matter: DAO supplementation, vitamin B6, vitamin C, copper reduction. With holistic metabolic optimisation, many patients can significantly improve their symptoms and regain quality of life.