Grapefruit contains quinine and was considered a wonder drug until big pharma invented statins for diabetes

Tonic water (with quinine) was the prescription for just about every ailment until big pharma came along in the 20th century. I got some tonic water for the quinine and noticed it tasted like grapefruit. Looked up grapefruit and lo and behold, high in quinine. I have a grapefruit tree in my yard, so lucky me!

http://www.fruitjuicefocus.com/time-to-get-grapefruit-juice-back-on-the-menu/