Challenges in herbal research: a randomized clinical trial to assess blinding with ginger.
OBJECTIVE
To assess methods to blind study participants to encapsulated ginger (Zingiber officinale).


METHODS
A randomized double-blind placebo controlled trial.


METHODS
Eighty healthy male and female volunteers.


METHODS
Whether participants can accurately determine if they receive a ginger or placebo capsule and a bottle filled with ginger or placebo capsules.


RESULTS
Forty-two subjects correctly identified the capsule they received. Of those who received placebo, over 82% correctly identified their capsule. Only 22.5% of those who received ginger correctly identified their capsule. The likelihood of guessing ginger between the groups was statistically similar (p<0.01). 65% correctly guessed which bottle they had received (p=0.0073). Participants receiving the bottle filled with ginger capsules successfully identified their bottle 75% of the time (p=0.0016) compared to the 55% of the placebo group (p=0.5).


CONCLUSIONS
Volunteers cannot determine which type of individual capsule they receive but can distinguish a bottle filled with ginger capsules.
Zick
Suzanna M
SM
University of Michigan, Department of Family Medicine, 715 East Huron Street, Suite 1W, Ann Arbor, MI 48104, USA. szick@umich.edu
Blume
Amy
A
Normolle
Daniel
D
Ruffin
Mack
M
D000328:Adult; D004311:Double-Blind Method; D005260:Female; D020939:Zingiber officinale; D006801:Humans; D008297:Male; D010919:Placebos; D028321:Plant Preparations
D010919:Placebos; D028321:Plant Preparations