Certain foods can affect CBD bioavailability. In a 2013 study published in the European Journal of Clinical Pharmacology, researchers assessed the effect food had on single-dose bioavailability of a delta- 9-tetrahydrocannabinol (THC) and CBD oromucosal spray among twelve healthy men. The study found that bioavailability was around four times higher when the spray was used following a meal than on an empty stomach.