In our current world, there is growing recognition of the benefits of plants used as herbal remedies for centuries prior. The June 2020 issue of YJBM (Focus topic: Plant-based Medicine and Pharmacology) puts particular attention on this continual growth in knowledge, featuring a range of studies on traditional herbal medicines. These include a review highlighting our current awareness of the role of kratom as an antipsychotic, as well as new studies on its effects on pain tolerance, two growing models surrounding the action of a centuries-old herbal remedy.
These traditional remedies include a group known as adaptogens, plants with multi-target effects allowing for the body to adapt to different stresses. This group includes Ashwagandha, Ginseng, Rhodiola, and many other plants that have become much more popular for use as health supplements. Koehler et al. explore the bioactivity of one member of this group, Astragalus membranaceus, an adaptogen used for centuries in Chinese herbal medicine. Historically used as a remedy for ailments like anemias, fevers, and fatigue, it is currently heralded for its powerful ability to modulate the immune system. Despite numerous studies investigating the biochemical makeup of Astragalus, there remains no conclusive identification of the bioactive compounds responsible for its effects. Much of the research on its immune system effects has focused on plant-derived compounds. Koehler et al., however, show meaningful evidence that the bacteria Rhizobium, which can be found living inside Astragalus plant cells, also produce immunoregulatory compounds. This contribution to the plant’s activity was not well appreciated until recently and will likely inform downstream studies on the underlying mechanism of Astragalus on immunomodulation.
Another common obstacle in the study of medicinal plants, as Koehler et al. mention, is the lack of a uniform standard for evaluating the therapeutic effects of plant-derived compounds. Gerontakos and collaborators address this issue also particularly important for adaptogens, assessing the current standard for how they are evaluated experimentally. In their review on recent studies on this topic, they found that these studies generally evaluated the therapeutic effects of adaptogens in terms of their cognitive, mood, and biological outcomes. While these categories allow some comparison of results across different studies, the use of different methods of evaluation sometimes led to contradictory results. In addition, many studies neglected to provide key information on their study design or even adverse safety events.
Despite an abundance of ongoing research, an understanding of the therapeutic effects of plant-derived compounds may not be possible without clear and consistent standards for their evaluation. In addition to the importance of ensuring their safety, there may be rightfully-founded concern about whether these supplements are sold for the true benefit of the general public if their physiologic activity, benefits, and risks are not adequately understood or clearly presented.