September 17, 2019
Wendy Ward1, Phillip Chilibeck2, Elena Comelli3, Alison Duncan 4, Stuart Phillips5, Lindsay Robinson4, Trent Stellingwerff6
1Department of Kinesiology, Brock University
2College of Kinesiology, University of Saskatchewan
3Department of nutritional Sciences, University of Toronto and Joannah and Brian Lawson Centre for Child Nutrition, University of Toronto.
4Department of Human Health and Nutritional Sciences, University of Guelph
5Department of Kinesiology, McMaster University
6Canadian Sport Institute Pacific- Performance Solutions, Athletics Canada ISST Lead
Nutritional supplements – a multi-billion-dollar global industry – are heavily marketed to consumers to optimize health, support well-being and improve performance. However, determining whether their purported effects are supported by high quality science can be challenging.
Given that studies with a strong experimental design provide the most reliable evidence, the overall goal of this paper was to provide researchers with guidance for designing experiments that will lead to the best quality science for decision makers. This includes consumers and those advising consumers about the use of commercially-available products. The authorial team, collectively representing broad expertise in nutrition, physiology, exercise, performance as well as clinical and preclinical trials, have developed a list of “must have” and optional “good to have” aspects that every study should consider in its design phase. Some of the practical questions to be considered include the following:
- Was the level of the component(s) of interest in the supplement characterized?
- Is there sufficient detail provided about the preparation of the product, and its composition including analyses performed, to ensure no cross-contamination and to understand the safety of ingredients and potential adverse health effects?
- Was there an assessment of the background diet and/or exercise?
- Was subject compliance confirmed?
- Was there a post-trial questionnaire confirming double-blinding of the intervention?
For those not involved with designing and conducting trials, but wanting to evaluate the reliability of the evidence, this paper essentially provides a ‘check-list’ of what to look for in a published study regarding efficacy of a nutritional supplement. In other words, studies that include these aspects in the ‘check-list’ can be considered of higher quality, providing greater confidence in the study findings and that similar effects will be experienced by consumers. In contrast, studies that do not include such aspects, and without a discussion of limitations resulting from the study design, may provide misleading findings. Of note is that these aspects are specific to studies of nutritional supplements, and, should be considered in addition to the usual standards of study design and reporting of findings detailed in the Consolidated Standards of Reporting Trials (CONSORT) statement (http://www.consort-statement.org/). It is also important to consider that many studies that show null or equivocal findings may not be published, making it even more important to carefully evaluate the quality of a published study.
- Studies that have the strongest experimental design can be considered of higher quality, providing greater confidence in the study findings and that similar findings will be experienced by consumers.
- Keep in mind that studies that have null or equivocal findings are published far less than those studies showing a positive effect.
Wendy E. Ward, Philip D. Chilibeck, Elena M. Comelli, Alison M. Duncan, Stuart M. Phillips, Lindsay E. Robinson, Trent Stellingwerff (2018). Research in nutritional supplements and nutraceuticals for health, physical activity, and performance: moving forward Appl. Physiol. Nutr. Metab. 44(5):445-460. doi: https://doi.org/10.1139/apnm-2018-0781.
This article is a summary of an article published in Applied Physiology, Nutrition and Metabolism. If you intend to cite any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Translation Committee.