Well, I've found another online reference to quinine content in
"The grapefruit contains a natural 'quinine' and hence is valuable in
the treatment of malaria. This 'quinine' is also beneficial in
The other fruit to watch out for is the humble cranberry:
"CRANBERRIES Fresh cranberry juice is a powerful healing tonic filled
with quinine which changes to hippuric acid in the liver."
Quinine is also related to coffee (they're both members of the
Rubiaceae family), and the bitterness in some coffee beans can be
attributed to high quinine content:
"Bitter: a basic taste characterized by solution of quinine, caffeine,
and certain other alkaloids."
Quinine is also used as a flavouring in liqueurs like Campari,
Dubonnet, Byrrh, Amer Picon and other bitter tipples. You would do
well to avoid bitter cocktails! Note that quinine is used in bitter
lemon mixer as well as tonic water.
Dictionary of Alcohol
I haven't *yet* found any references to quinine content in apples or
tomatoes, but I'm still looking and will post if I find anything
So: no grapefruit juice, no cranberry juice, no coffee, no gin and
tonic and no cocktails! May I recommend a cup of tea?