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An interesting evaluation winged its way into Editorial over the Christmas break, and got waved under my nose ahead of publication. According to a paper published in J Clin Psychopharmacol last August, a double-blind placebo-controlled trial of oral chamomile extract showed a modest anxiolytic activity in patients with mild to moderate generalized anxiety disorder.

Despite the study’s small sample size (and the modesty of the authors) it seems to be a reasonable trial, and looks like chamomile is actually beneficial over placebo, in its first randomized, double-blind, placebo-controlled, parallel-group trial. This is big news for herbal therapies (yes Virginia, they do have active ingredients; unlike homeopathic prepartions).

However, the authors also say

We did not use a specific patient or clinician-rated measure
to verify the adequacy of the blinded conditions. Thus, it is possible that unrecognized rater or patient or clinician bias may have contributed to the superiority of chamomile over placebo

(my emphasis)

which leads me onto something a friend pointed out when I brought the paper to her notice. Chamomile has a reasonably strong and distinctive odour and flavour. If the preparation used retained either of these, then the placebo effect could still be in play.

I have finally managed to get hold of the full paper, however, and deep in the Materials section I find

Blinding of the characteristic chamomile aroma was achieved by inserting a disk impregnated with 1 drop of chamomile oil (for placebo) or 1 drop of neutral oil (for chamomile) into the lid of each airtight medication container

which is a great start, but I don’t know if it would be enough. Anyone have any thoughts on this?

Amsterdam, J., Li, Y., Soeller, I., Rockwell, K., Mao, J., & Shults, J. (2009). A Randomized, Double-Blind, Placebo-Controlled Trial of Oral Matricaria recutita (Chamomile) Extract Therapy for Generalized Anxiety Disorder Journal of Clinical Psychopharmacology, 29 (4), 378-382 DOI: 10.1097/JCP.0b013e3181ac935c