When consuming or studying herbal supplements, one must remember that bioactive compounds can vary drastically with the growing conditions of the plant. At this point, concentrations of bioactives are not regulated in most herbal supplements and one cannot rely on uniformity from one batch to the next. Hopefully, this will change in the future as scientists further identify the active compounds in foods/supplements and are able to produce more consistent products.
    It is imperative for the bioactive to reach its target tissues so, in the case of the glandulars specifically, it should be advised to wait to see performance benefits in a controlled scientific study before investing in these agents.
    With ginkgo, ginseng, green tea, and garlic, these foods are all of plant nature and have been consumed by humans for many generations. It is very likely that the risk of side effects occurring from regular use is low. However, extracts and concentrated forms of these same agents have an increased potential to cause harm. One must be cautious if ingesting large amounts of bioactive compounds.
    Of the 5 supplements reviewed here, the authors concluded that green tea has the highest potential to demonstrate ergogenic effects from habitual use.