Athletics and Herbal Supplements
Do current products enhance athletes’ health and performance?
A Multidisciplinary Framework
Herbal supplement sales, the number of available herbs and the number of preparation types have all grown in recent years, and many of these are popular among American athletes (see Figure 2). Despite this burgeoning industry, research on supplements’ effects on human biology remains inconclusive overall, and athletes are often left to trust manufacturers’ claims or teammates’ advice when it comes to making choices about what supplements to take and whether to take them.
Early studies of any herbal supplement are almost exclusively of the clinical variety. They strive to address questions of efficacy by testing supplements available for over-the-counter purchase. Studies often include detailed information on subjects’ characteristics, dosing regimens, methods for assessing efficacy and, in athletic studies, aerobic endurance exercise or anaerobic strength training regimens. But such studies frequently lack information about the chemical contents, botanical origin or agricultural provenance of the supplements. In addition, medical pilot studies are often characterized by small sample sizes, and a paltry number of studies typically exist for a given herb. This complex interplay of factors makes results hard to replicate or interpret and makes it difficult to identify confounding variables among studies.
Even when every study for an herb is stalwartly reviewed, one is typically forced to conclude that the data are equivocal—for every study that supports efficacy, another refutes it, even after controlling for demographics, dosing and so forth. The predictable outcome is confusion and miscommunication within the sports science community.
Dovetailing botany, chemistry and medical disciplines from cell biology to physiology is absolutely critical to the advancement of research on herbal supplements in athletic contexts. In addition to many others’ work on this subject, collaborators from Drake and Iowa State Universities Nisarg Shah, Danielle Doty, Cole Sanderson, Justus Hallam and I have developed novel experimental data on previously neglected preclinical factors. The species of plant chosen, the location from which the plant was gathered, the specific organ extracted or the extraction method may in large part explain the heterogeneous clinical outcomes.
One of the biggest challenges such a multidisciplinary approach presents is conceptualizing the myriad preclinical and clinical factors that can potentially influence a trial. In a 2009 article in Exercise Immunology Review, we proposed a conceptual model for this multidisciplinary approach. We originally categorized factors in our model by botanical, chemical and clinical disciplines. Our revised seed-to-stomach model incorporates these as well as commercial factors to better reflect the societal context of herbal supplement research (see Figure 3). The model discourages the mistaken conclusion that equivocal is synonymous with ineffectual, moving the field from simplistic questions of “Does a given supplement ‘work’?” to “Under what conditions does a given supplement produce a given outcome?”