In a randomized controlled trial, 30 pigs were orally treated with histamine (60 mg). In addition, half of the animals underwent a specific blockade of the enzyme diamine oxidase (DAO), which is the main histamine catabolising enzyme in the intestinal tract. Only these DAO-blocked animals exhibited severe clinical symptoms (e.g. hypotension, flush, vomiting) and, in parallel, showed tremendous elevations of plasma histamine levels of up to 160 ng/ml. 3 out of 15 animals in this group died within the experimental period. In contrast, the control animals neither exhibited plasma histamine levels above 5 ng/ml nor had any clinical reactions. These results contradict the current opinion that oral histamine intake in food is not clinically relevant, especially since many commonly used drugs are DAO-inhibitors and approximately 20% of our population take these drugs. Apart from drugs, some other factors (alcohol, spoilt food etc.) can also function via a blockade of DAO as an additional risk. DAO-blockade is therefore a real epidemiological problem. Evidence is presented here for the new disease concept: Food-Induced Histaminosis.