Study to Investigate the Effect of an Oral Diamine Oxidase Substitution (DAOsin) in Histamine Intolerant Patients on the Low Endogenous Diamine Oxidase Serum Activity

Inclusion Criteria: * diamine oxidase activity \< 10 U/ml * \>= 2 symptoms of histamine intolerance after consumption of histamine containing food * 18 to 80 years * no lactose intolerance * no fructose intolerance * no tissue transglutaminase antibodies in serum Exclusion Criteria: * pregnancy and nursing * cardiopathy * instable hypertonie * asthma bronchial * lactose intolerance, fructose intolerance, coeliac disease * severe liver and kidney diseases * Known food and other allergies * participation in clinical study the last 4 weeks * recent (3 months) operation affecting the gastrointestinal tract * maligne, infectious or autoimmune gastrointestinal diseases (e.g. IBD) * taking histamine liberating drugs on a regular basis * taking diamine oxidase inhibiting drugs on a regular basis * taking diamine oxidase supplements on a regular basis in the last 4 weeks * H1 blocker or Montelukast Therapy 4 month before study start * Taking anti histaminica * Taking zinc preparations * drug, alcohol, pharmaceutical abuses * heavy smoking (\>15 cigarettes a day) * Known HIV infection * known acute or chronic hepatitis B and C infection