Efficacious blinding of ginger for randomized controlled trials

Ginger Zingiber Officinale Roscoe)has a distinct aroma that is difficult to blind in randomized controlled trails. We tested whether packaging encapsulated ginger in blister packs leads to effective blinding. We recruited 32 healthy volunteers age 18 and up through advertisement in the University of North Carolina and the community. They were asked to examine either 1 clear gelatin capsule of 250 mg of ginger powder or 1 similar looking clear gelatin capsule of placebo (brown sugar) in a blister pack before and after opening the pack; after which they were asked to swallow the capsule. Sixty percent correctly identified capsules filled with placebo versus 23.4% correctly identified capsules filled with ginger. x2 tests revealed no differences between the two treatment arms in content (the majority thought they were taking a placebo), look, smell and taste of the capsules. Prior familiarity with ginger did not increase prediction rates. Our results demonstrate that ginger can be effectively blinded by packing individual capsules in blister packs.