Von Alex Maier. Update 06/11/2014
Many people do not know, that not only medicament, but also normal nutrition can cause interactions with medicament and can even render them ineffective.
Grapefruit-juice inhibits medicament
One of the most problematic substance is grapefruit. Many people only know it as healthy and vitamin C rich, especially in the winter time. But there already exist 43 medicament, which loose their effect when consumed with grapefruit, as David Bailer from the University of Western Ontario does write in the specialist magazine “Canadan Medical Association Journal“.
Grapefruit-juice inhibits the enzyme Cytochrom-3A4-Enzym (CYP3A4). Without this enzyme medicament can not be metabolized and are excreted.
St. Johnswort increases effectiveness
The opposite effect does have St. Johnswort, which is often used as mood enlightening medicament. It does increase the activity of the same enzyme and therefor does increase the effect of many medicament.
Even calcium (e.g. contained in milk) and special OTC against heartburn can cause side effect with medicament.
Therefor patients should read the package leaflet carefully and ask their doctor or pharmacist if unsure.
Source: Welt.de, 09.12.12.