D-Linmonene: Eating all the Orange NOW seems like a good Idea, %90 had tumors disappear in study.
D-limonene
D-limonene is a terpene, a compound found in plants. The best source of d-limonene is the oil from orange peels. Researchers at the University of Wisconsin found that when d-limonene was added to the diets of rats who had developed tumors, 90% of them had their tumors disappear completely. In a related study, animals that were given d-limonene one hour before being exposed to known carcinogens, were protected from the effects of the carcinogens at a highly significant rate.
In rats, large doses of d-limonene produce kidney problems, but in dogs, there were no side effects.
D-limonene has yet to be tested on humans, and since very little of the two billion spent annually on cancer research ever makes it to clinical studies, it might never be tested on humans to determine dosages and toxicity levels, if there are any.
In the meanwhile, you can do what most juice experts have been saying for years: juice the orange and the peel together—just make sure your oranges are organically grown. [Alternatives, September 1991; 4: 3]
http://www.mnwelldir.org/docs/cancer1/altthrpy.htm