Goji berries are extolled on the internet as "wonder fruits for everyone" or "one of the best foods in the world" (1). The fruits of this member of the nightshade family (goji or wolfberry; Lycium barbarum), which have been used for centuries in traditional Chinese medicine, are claimed to strengthen the immune system and the heart, lower blood lipids, have anti-ageing properties and much more. The fruits themselves and preparations such as teas, juices, jams, etc. are available on the market (2).

However, some constituents of goji berries can interact with medicines - sometimes with life-threatening consequences. This is demonstrated by four case reports compiled by an author from the Federal Institute for Drugs and Medical Devices (BfArM) (2). Hence three or four cups of goji tea daily or 30 ml of goji juice twice daily can disrupt previously stable anticoagulant control achieved with coumarins after just two days and can result in severe bleeding. The mechanism of action is not known, although blocking of the cytochrome P450 enzyme CYP2C9 has been discussed. The interaction is already listed in the product information of coumarin anticoagulants in Canada but it is still under discussion in Europe (2).

Anyone taking coumarin anticoagulants should be warned against consuming goji products. If an unexpected increase in INR values is noted, it is advisable to ask specifically whether goji berries or goji preparations are being used.

We advise against goji consumption. Goji berries are not among the customary foods eaten in this country. Thirteen out of 14 samples of conventionally grown goji berries were rejected on the basis that they exceeded the maximum levels of pesticides (3). In any case, we assign the promised effects of goji to the realm of quackery.

1

e.g. www.zentrum-der-gesundheit.de/goji-beeren-ia.html

2

FLÜGGE, I.: Bull. z. Arzneimittelsicherheit 1/2013: 13-7

3

Chemisches und Veterinäruntersuchungsamt (CVUA) Stuttgart: Nachgefasst: Pestizide in Goji-Beeren, 3. März 2010; http://cvuas.ua-bw.de/pdf/druck_pest_gojibeeren2010.pdf