Scientific skepticism and new discoveries: An analysis of a report of zinc/phytase supplementation and the efficacy of botulinum toxins in treating cosmetic facial rhytides, hemifacial spasm and benign essential blepharospasm

摘要

Introduction: A recent paper in the Journal of Drugs in Dermatology by Koshy and colleagues (2012, 11(4):507-512) report on "Effect of Dietary Zinc and Phytase Supplementation on Botulinum Toxin Treatments" and conclude by claiming the discovery of "a potentially meaningful role for zinc and/or phytase supplementation in increasing the degree and duration of botulinum toxin effect in the treatment of cosmetic facial rhytids, benign essential blepharospasm, and hemifacial spasm". The purpose of this paper is to examine these published claims for possible methodological and design errors and potential sources of bias. Methods: The authors evaluated the published results in comparison to the published literature on zinc deficiency, the role of phytase, prior reports of an effect of zinc on activity of botulinum toxin, issues of study design and execution and if the reported results of the study supported the study's conclusions. Results: Multiple issues are present in the reported study, which appear to invalidate its conclusions. These areas include lack of direct evidence for the presence of clinical or subclinical zinc deficiency in the study population or for the level of phytate in the study population sufficient to interfere with zinc absorption in these subjects. Additionally, there is ambiguity as to the actual dose of zinc used as well as in the study design itself. Also there is a failure of the study through the "unmasking" of the crossover design. There is potential financial conflict of interest in the study execution that may have biased the reported results. Finally there is inadequate data presented to evaluate the claims made of a "new discovery" as to the three disease entities reported on and the various botulinum toxins used in each of the three treatment arms of the study. Discussion: Based on this evaluation, it appears that a high level of clinical and scientific skepticism is warranted concerning any claim of a beneficial effect of zinc and phytase supplementation on the efficacy or potency of any botulinum toxins in the reported conditions.