Reviewed: Harnett J, Oakes K, Caré J, et al. The effects of Sambucus nigra berry on acute respiratory viral infections: A rapid review of clinical studies. Adv Integr Med. December 2020;7(4):240-246. doi: 10.1016/j.aimed.2020.08.001.
European elder (Sambucus nigra, Adoxaceae) berries and flowers have been used traditionally to treat common colds and the flu. Elder berry extracts have been shown to have antimicrobial and antiviral properties. Some preclinical studies have shown that elder berry extracts demonstrate positive effects against influenza virus infection, specifically by inhibiting viral replication and increasing both pro-inflammatory and anti-inflammatory cytokines involved in the immune response. The purpose of this review was to determine whether elder berry extract improves outcomes in patients with acute respiratory viral infections (ARVIs).
A keyword search was performed for articles in MEDLINE, Embase, the Allied and Complementary Medicine Database, and the Cumulative Index to Nursing and Allied Health Literature database from inception through May 2020. Included articles were original prospective intervention studies using adult participants with ARVIs, written in English, and evaluated elder berry (as a mono- or combination therapy) in any form, dose, and route of administration. Studies that involved children only or participants with fungal or non-infectious respiratory diseases were excluded. Forty studies initially were identified and five met all inclusion criteria.
The pooled sample size was 936 participants between five and 70 years of age, with two studies also including both children (5-12 years of age) and adults (18 years of age and older). The included studies were conducted in Australia (n = 1), China (n = 1), the Czech Republic (n = 1), Israel (n = 1), and Norway (n = 1). The conditions studied included influenza (n = 2), influenza-like symptoms (n = 2), and the common cold (n = 2).
Four studies used mono-herbal preparations of elder berry extract, and one study used a poly-herbal blend of elder berry and echinacea (Echinacea purpurea, Asteraceae) root (Table 1).
Two of the five studies showed “some concern” for bias according to the Cochrane risk of bias assessment tool; the remaining three studies reported a low risk of bias. A meta-analysis was not conducted due to heterogeneity of the data.
In general, significant reductions of symptoms and shorter duration of illness were observed in the mono- and poly-herbal groups compared to the control groups. All studies reported a significant reduction in the severity of overall symptoms and fever specifically, and one study also reported significant reductions in cough, headache, mucus discharge, muscle ache, and nasal congestion symptoms.
Duration of illness was reported in four studies, with consistent outcomes. The poly-herbal study reported a similar, non-inferior rate of recovery compared to oseltamivir (an antiviral medication). Three studies reported an almost 50% reduction in duration of illness in the elder berry groups versus the control groups. Two studies reported the use of rescue medications (including analgesics, antibiotics, cold tablets, and nasal sprays) in elder berry and control groups, but the need for these medications was not consistent.
No serious adverse events were reported. Adverse events included cold-like symptoms, fatigue, itchy throat, and kidney pain. Nausea and vomiting were reported in the study using the poly-herbal blend.
The authors conclude that mono-herbal preparations of elder berry extract, when taken at the onset of symptoms and for up to two weeks, may provide relief from symptoms of the common cold and influenza. They also note that elder berry extract may be effective in reducing duration and severity of fever, headache, nasal congestion, and nasal mucus discharge associated with ARVIs. However, the “evidence regarding the effectiveness of S. nigra berry on the symptom of cough, and need for/use of medicines (including antibiotics) to treat ARVIs, is currently unclear and inconsistent,” they explained.
As the formulation, dose, and duration of elder berry treatment varied across studies, additional research is needed to further evaluate the efficacy and safety of elder berry extracts for ARVIs.