DAOsin is a food supplement for special medical purpose for the treatment of food intolerance provoked by histamine intake. In this uncontrolled, interventional pilot study the effect of an oral diamine oxidase substitution (DAOsin) on the reduced endogenous diamine oxidase activity in histamine intolerant patients will be examined.

Patients with a low endogenous diamine oxidase activity (below 10 Units/ml) take DAOsin for one month 3 times a day. During this month the diamine oxidase activity is tested biweekly. Afterwards a follow up period of one month without taking DAOsin follows. Again the diamine oxidase activity is tested biweekly.

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