Presse Med. 2002 Sep; 31(30): 1416-22.

[Metabolic effects and drug interactions provoked by certain vegetables: grapefruit, St. John's wort and garlic]

Neuman M.

GRAPEFRUIT: Essentially consumed in the form of juices with its bitterness helping to quench thirst, grapefruit contains not only vitamin C but also many complex antioxidizers, licopene, lemonoids and naringine. It also contains large quantities of pectin. Grapefruit juice is a metabolic inhibitor of medicinal substances that constitute an exclusive target for the CYP 3A4 isozyme and glycoprotein P in the enterocytes. Above all, it affects the drugs with strong intestinal metabolic first pass effect, phenomenon provoking the reduction of their oral bioavailability. This metabolic inhibition is manifested by an increase in the serum levels, oral bioavailability and therapeutic activity of drugs metabolized by CYP 3A4, a characteristic that may indeed be interesting for some of them, but which should be avoided for others. ST. JOHN'S WORT: (Hypericum perforatum) Also known as "herbe Ã mille trous" or "herbe percÃ©e" or even "herbe de Saint-Jean" in France, St. John's wort is used in several therapeutic fields: neuropsychiatry, dermatology (oleate or lipid extract) and in rheumatology. In herbal remedies and homeopathy, the flower heads are often prescribed as antidepressor in the treatment of mild to moderate depression. It also contains photosensitizing substances, which, at high dose, or during chronic use, may provoke intense dermatitis or photosensitivity. The potential occurrence of side effects with its use has led the European Agency for drug assessment and the French Medicines Agency to decree that all magistral preparations containing St. John's wort must be labeled: "Warning, risk of drug interactions". GARLIC: (Allium salivum) Originating from Asia, widespread and cultivated in Europe in kitchen gardens, garlic is used by herbalists for its diuretic, antiseptic, stimulating and sudorific properties.