Interview with Liesbeth Veldman (student at Wageningen University)

A systematic review on the working mechanisms of four herbal preparations for acute, uncomplicated respiratory tract infections

Liesbeth Veldman (Msc) studied Nutrition and Health at the Wageningen University. For her internship at Leiden University of Applied Sciences she conducted a systematic review on the working mechanisms of four complementary and alternative medical (CAM) treatments for acute, uncomplicated respiratory tract infections (RTIs). The treatments included the herbal preparations of Andrographis paniculata, Pelargonium sidoides, Echinacea species and a combination of Ivy (Hedera helix), primula (Primula veris and Primula elatior) and thyme (thymus vulgaris and thymus zygis). Next to the review Liesbeth interviewed three experts in the CAM research field to obtain in depth information on the working mechanisms, implications for further research and acceptance of the products.

The four preparations were chosen, since these came forward as most promising preparations based on a systematic review of systematic reviews (under review) of the clinical effects of CAM treatments of acute, uncomplicated RTIs. Subsequently, Liesbeth reviewed mainly in vitro and in vivo studies on the mechanistic background of the clinical health effects. The study shows there is scientific mechanistic evidence for one of the main benefits of CAM medicinal products: strengthening the biological resilience of the patient. This is achieved by among others strengthening the immune system, reducing inflammatory damage and reducing disease symptoms. This is in addition to the fighting disease working mechanism of targeting the pathogen directly. The study nicely shows the evidence for different routes of actions per herbal preparation.

For further research, each herb has their own challenges. For example, Echinacea spp. are studied in many different forms and preparations, using different species, preparation and extraction methods. This results in final products with varying (chemical) compositions. In order to make a strong conclusion, first, a distinction should be made between effective and ineffective preparations. Consequently, more research should be done on the effective preparations. On the other hand, Pelargonium sidoides research is mainly done with one standardized extract, which gives a clear picture of the working mechanism of the specific extract. For this product, next steps would include clinical research on side effects, acceptance by patients and physicians and integration of the product in mainstream healthcare (in some countries Pelargonium sidoides is already in the conventional guidelines).

In the next months a publication of the systematic review will be submitted to a scientific journal.