By Sarah Crawford, PhD
The yearly flu outbreak is going around the office. You wake up one morning with coughing, fever, muscle aches, …. oh, no! You have a big presentation due tomorrow. Is there anything you can do? You pick up the newspaper, and there it is! Promising research suggests that extracts from the elderberry plant may help to lessen the severity and shorten the duration of the flu. Is this true, or is it just hype? Let’s take a look at the evidence.
The elderberry fruit has been the object of several clinical trials worldwide designed to determine whether it can alleviate the symptoms of the flu or even shorten the illness. While these studies all boast positive benefits, it is important to analyze the data with a critical eye before drawing any conclusions. The research on the anti-viral effects of the elderberry is in two platforms: therapeutic benefit in patients sick with the flu and research on the mechanism responsible for its anti-viral effects. Both platforms need to be addressed to make a solid case for therapeutic benefit. This article focuses specifically on the perceived patient benefit; if positive results are obtained, this warrants a physiological assessment of the anti-virus components of the berries.
The Data Files
First, the good news: the consensus of clinical patient research suggests that consumption of some form of elderberry at early onset of the flu can, in some people, shorten its duration and alleviate its symptoms, including coughing, muscle aches, and fatigue. Moreover, major clinical trials evaluating the effects of elderberry in patients with the flu have generally employed a study design in which one group of patients receives the elderberry treatment and the other only a placebo. This can be an effective way of determining whether there is any positive benefit derived from the treatment. The studies were also double-blinded, which means that neither the patients nor the researchers know which patient group receives the experimental treatment.
So far, so good; however, the data are far from conclusive and fall short of suggesting that consuming elderberries should be advocated currently to treat the flu. There are several major issues that need to be addressed before any definitive conclusions can be made. First of all, more human clinical trials are needed. So far, the anti-viral effects of this berry have been tested only in small, sporadic trials.
Secondly, the size of the trial- the number of enrolled individuals- has been small in most of the reported studies. The larger the sample size, the more quantifiable the results and the greater the likelihood that the results will apply to the population at large. For example, a clinical trial by Zakay-Rones et al. in Norway during the flu outbreak of 1999-2000 enrolled a cohort of only 60 patients.1Zakay-Rones Z, Thom E, Wollan T, Wadstein J. Randomized study of the efficacy and safety of oral elderberry extract in the treatment of influenza A and B virus infections. J Another trial by Kong in 2009 in China enrolled only 64 patients.2Kong F. Pilot clinical study on a proprietary elderberry extract: efficacy in addressing influenza symptoms. Online J Pharmacol Pharmacokinet. 2009;5:32–43. A more recent clinical trial (2013-14) based in Australia involved a randomized trial of 312 study subjects.3Tiralongo, Evelin, Shirley S. Wee, and Rodney A. Lea. Elderberry supplementation reduces cold duration and symptoms in air-travellers: A randomized, double-blind placebo-controlled clinical trial. Nutrients 8.4 (2016): 182. It is very difficult to extrapolate the responses obtained in small patient groups to wider applications.
A further issue of concern is that the elderberry supplements used in the trials were of several different types, different preparations and were combined in some cases with other supplements. For example, a clinical trial by Zakay-Rones et al.1Zakay-Rones Z, Thom E, Wollan T, Wadstein J. Randomized study of the efficacy and safety of oral elderberry extract in the treatment of influenza A and B virus infections. J , in Norway during the flu outbreak of 1999-2000 used a preparation called Sambucol, an elderberry syrup. Another clinical research study conducted in China in 2009 used a proprietary (patented, secret) slow-dissolve lozenge formulation of elderberry of unknown composition (Kong).2Kong F. Pilot clinical study on a proprietary elderberry extract: efficacy in addressing influenza symptoms. Online J Pharmacol Pharmacokinet. 2009;5:32–43. A more recent clinical trial (2013-14) based in Australia treated patients with a membrane-filtered elderberry extract (Sambucus nigra L.) that contained 300 mg of elderberry extract 15% anthocyanins and 150 mg of rice flour.3Tiralongo, Evelin, Shirley S. Wee, and Rodney A. Lea. Elderberry supplementation reduces cold duration and symptoms in air-travellers: A randomized, double-blind placebo-controlled clinical trial. Nutrients 8.4 (2016): 182. These differences in elderberry species, concentration and the presence of additional components in some formulations make it virtually impossible to assess directly the effectiveness of the elderberry fruit in these clinical trials.
The methods used to evaluate the effectiveness of the elderberry supplements in treating the flu were also problematic. In several clinical trials, therapeutic efficacy was determined using a Visual Analog Scale (VAS) involving self-reporting by patients of the severity of their flu symptoms. Patients were asked to rate their symptoms post-treatment on a scale of 1-10, with 10 representing the highest level of discomfort. This type of data collection is highly subjective and reported values might be susceptible to varying interpretations of the scale by individual patients. A much better approach would involve the use of objective, measurable symptom assessment by trained professionals. These evaluations might include body temperature, respiratory indices and chest X-rays where applicable. Quantitative assessments comprise a far more rigorous database that can be assessed statistically to determine the overall relevance of the findings.
Despite these study limitations, the consensus of human clinical trial data suggests that there is “good” scientific evidence that elderberry extracts lessen the severity and the duration of the flu, according to a thorough review of the anti-viral effects of the elderberry (Sambucus spp.), by Ulbricht et al.4Ulbricht, Catherine, et al. An evidence-based systematic review of elderberry and elderflower (Sambucus nigra) by the Natural Standard Research Collaboration. Journal of dietary supplements 11.1 (2014): 80-120. Tests to measure the effects of the elderberry formulation included immune antibody production against the flu virus, clinical flu symptoms, and respiratory distress levels. Overall, these studies indicated moderate positive effects on symptom intensity and duration as a result of elderberry treatment in patients with the flu. For example, Kong reported that 28% of the patients who took the elderberry lozenges showed complete recovery, whereas in the placebo-treated control group, no patient reported complete recovery during this time-frame.2Kong F. Pilot clinical study on a proprietary elderberry extract: efficacy in addressing influenza symptoms. Online J Pharmacol Pharmacokinet. 2009;5:32–43. No adverse side effects were reported in any of the clinical trials.
CONCLUSION: Where do we go from here?
You may be wondering at this point when/if we will be able to say definitively whether elderberry is an effective treatment for the flu. While the clinical trial data look promising, there is still a lot that needs to be accomplished before we can answer this question with a high degree of certainty. Additional clinical trials are needed that enroll a large number of patients (as large as possible) as well as demographically diverse patient populations. It is essential that elderberry extracts of uniform concentration, method of preparation and solvent composition be used in clinical studies designed to determine the efficacy of this therapeutic protocol. Moreover, it will be important to define dosing levels and schedules that provide the greatest therapeutic impact.
Patient responses must be evaluated by clinicians using objective response tools rather than relying on patient self-assessment to define more accurately the clinical benefit of elderberry supplements.
Once these experimental criteria are met, it will be possible to determine conclusively whether elderberry extract formulations provide a beneficial effect in the treatment of flu.
Related article: Can Elderberry Cure the Flu?