The best study I have yet met on the indications and contraindications of quinine in bitter drinks, is undoubtedly the one published in 2008 by BfR which is the German Federal Institute for Risk Assessment and was established as a federal authority under the jurisdiction of the Federal Ministry of Food and German agriculture (BmEL). Here is the first part. The study is very long, about 16 pages and contains all the bibliographical references:

Quinine is a bitter-tasting, crystalline white powder. It is obtained from the bark of the cinchona tree and belongs to the group of alkaloids. In medicine quinine is used to treat malaria and nocturnal leg cramps. In the food sector, quinine is used as a flavouring mainly in beverages like bitter lemon and tonic water.

When larger amounts of quinine are consumed, it can constitute a health problem for some consumer groups. BfR sees risks in particular for quinine intakes during pregnancy. For instance, a newborn baby, whose mother had drunk more than 1 litre tonic water a day in the weeks up to its birth, suffered health disorders. Based on existing regulations in the medicinal product sector, BfR, therefore, advises pregnant women against drinking quininecontaining beverages on precautionary grounds. People who have been advised against taking quinine, cinchona bark or their preparations by their doctors because of their clinical pictures should not consume any quinine-containing soft drinks either. This applies, for instance, to people who suffer from tinnitus, pre-existing damage to the optic nerve, haemolytic anaemia or who are hypersensitive to quinine or cinchona alkaloids. Patients with cardiac arrhythmia and people who take medicine that interacts with quinine, should only drink quinine-containing soft drinks after consulting their doctors. This applies in particular to medications which inhibit blood coagulation. At higher levels of tonic water consumption, it may be necessary to reduce their therapeutic dose.

Already today quinine must be mentioned by name in the list of ingredients of quininecontaining products. BfR also believes that there is a need for information which attracts the attention more particularly of pregnant women and other risk groups to possible health impairments. Motor vehicle drivers should be informed that larger amounts of quininecontaining bitter beverages can cause visual disturbances. BfR recommends raising awareness about the possible health risks from quinine to consumers. Specific information should be provided about the symptoms of quinine hypersensitivity and cinchonism (typical adverse reactions to quinine). Consumers should be advised to immediately stop their quinine intake if these symptoms occur, and to consult a doctor.

BfR recommends that the health assessment of quinine by the Scientific Committee on Food from 1988 should be updated.

BfR is of the opinion that the problems of quinine-containing bitter soft drinks underline the importance of the systematic recording of adverse reactions that occur in conjunction with the consumption of foods. The Institute, therefore, explicitly supports the setting up of a central reporting office (1).

References___________________________________________________

(1) Quinine-containing beverages may cause health problems
Updated BfR Health Assessment No 020/2008, 17 February 2005