Some studies that support this concept:

Histamine-free diet: treatment of choice for histamine-induced food intolerance and supporting treatment for chronic headaches.

Histamine and histamine intolerance.

A Histamine-Free Diet Is Helpful for Treatment of Adult Patients with Chronic Spontaneous Urticaria.

A Popular myth – low-histamine diet improves chronic spontaneous urticaria – fact or fiction? (The answer: yes).