The main results of our study show that a standard clinical dose of CBD in corn oil formulation did not convert into THC in humans under fasting and normal feeding conditions. We found no signs of Δ8-THC or Δ9-THC in whole blood at 3 and 6 h after oral administration of CBD. The findings are supported by the results of previous, methodologically adequate animal studies using oral CBD. In a study with male rats (Sprague Dawley), oral CBD (50 mg/kg) dissolved in olive oil and ethyl alcohol was administered, and the animals were sacrificed after 3 or 6 h. Despite the use of a highly sensitive and selective LC-MS/MS method, the authors found no signs of Δ9-THC or its metabolites (11-hydroxy-D9-tetrahydrocannabinol [11-OH-THC], THCCOOH, and THCCOOH-gluc) in whole blood at 3 or 6 h after oral CBD. The possibility of the conversion of CBD to Δ9-THC has also been investigated in minipigs, which is considered a suitable animal model for the human gastrointestinal tract. Synthetic CBD (15 mg/kg) dissolved in sesame oil was administered by gavage to male minipigs twice a day for 4 days, and blood samples were collected from the jugular vein on days 1 and 5, just before, and 1, 2, 4, and 6 h after CBD administration. No detectable levels of both Δ9-THC and 11-OH-THC were found in any of the plasma samples collected.