Randomized Clinical Trials

The scientific literature below are interesting studies to empower you so that you can make informed decisions. This is to be used for educational purposes only and is not medical advice.  Please partner with your wellness team and share these studies with them.

We’ve partnered with Dr. Cathy Stein to help our community understand these articles by creating easy-to-understand summaries. Dr. Cathy Stein has a PhD in epidemiology and her research focuses on infectious disease susceptibility.  She currently holds a tenured faculty position.

Randomized clinical trials (RCTs) are a type of study design in which participants are randomly assigned to receive one of two or more interventions, with the goal of determining which intervention is more effective. Like any study design, RCTs have their advantages and disadvantages.

Pros of Randomized Clinical Trials:

  1. They are considered the gold standard for evaluating the effectiveness of medical interventions because they are designed to minimize bias and confounding variables.


  2. They provide a high level of evidence for determining causality between the intervention and the outcome.


  3. They can be used to evaluate the effectiveness of new treatments or interventions, as well as to compare different treatments to determine which is more effective.


  4. They can help identify unexpected side effects or complications of treatments, which may not have been identified in earlier phases of research.

Cons of Randomized Clinical Trials:

  1. They can be expensive and time-consuming to conduct, which can limit the number of RCTs that are conducted.


  2. They are restrictive with their criteria (what’s included and what’s excluded) which makes them hard to conduct and very time consuming (see ‘expensive’ as well)


  3. They may not be feasible for all research questions, especially if the intervention being studied is already widely used or if the condition being studied is rare.


  4. They may not be generalizable to all populations, as the participants in the study may not be representative of the broader population.

Notes about comparing these studies

While all the studies used S. nigra, the formulation was different in all the studies except “Inhibition of Several Strains of Influenza Virus in Vitro…” and “Randomized Study of the Efficacy and Safety of Oral Elderberry Extract…” which used the same one.

The last study (“Elderberry Extract Outpatient Influenza Treatment…”) initially started by recruiting only “high-risk” subjects (older, multiple comorbidities, etc) and then changed inclusion/exclusion criteria to include lower risk subjects to increase generalizability.  However, the other publications were not as transparent regarding whether comorbidities were part of inclusion/exclusion criteria.  One potential implication of this difference between studies is that the study including a higher proportion of older/comorbid subjects may have found a negative result because individuals with comorbidities might not benefit as much from elderberry.  Certainly, a definitive conclusion like this would require additional study. In addition, it would be useful if these RCTs gave better detail about their patient populations regarding pre-existing conditions.

Elderberry composition by study:

Randomized Study of the Efficacy and Safety of Oral Elderberry Extract in the Treatment of Influenza A and B Virus Infections” – Sambucol®, Razei Bar, Jerusalem, Israel). The syrup formulation contained 38% of the standardized extract plus small amounts of raspberry extract, glucose, citric acid and honey. Standardization of the flavonoid content was maintained by ensuring the absorbance at 516 nm was above 0.60.

“Inhibition of Several Strains of Influenza Virus in Vitro and Reduction of Symptoms by an Elderberry Extract {Sambucus nigra L.) during an Outbreak of Influenza B Panama” – Sambucol® (Razei Bar Ltd, Jerusalem) is a syrup containing elderberry juice, raspberry extract, glucose, citric acid, and honey.” (same as above)

Elderberry Supplementation Reduces Cold Duration and Symptoms in Air-Travellers: A Randomized, Double-Blind Placebo-Controlled Clinical Trial” – Elderberry capsules were manufactured by Plantafood in Germany.  300 mg of elderberry extract (22% polyphenols (i.e., quercetin and its glycosides, rutin), 15% anthocyanins (i.e., cyanidin and pelargonidin glycosides) and 150 mg of rice flour.

“Elderberry Extract Outpatient Influenza Treatment for Emergency Room Patients Ages 5 and Above: a Randomized, Double-Blind, Placebo-Controlled Trial” – Each 15-ml dose of the oral liquid contained the fruit juice equivalent to 5.7 g of Sambucus nigra (black elderberry).

“Pilot clinical study on a proprietary elderberry extract: Efficacy in ad-dressing influenza symptoms” –  Lozenge with 175 mg proprietary elderberry extract taken 4 times/day.

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