Black Elderberry (Sambucus nigra), a fruit-bearing shrub native to Europe and North America, has long been researched for its immune boosting potential. Elderberry is unusually rich in anthocyanins, a class of flavonoids that may protect cells against damage or infections. Clinical and experimental studies suggest elderberry fruit extract is particularly useful against viral influenza.
Vlachojannis JE, Cameron M, Chrubasik S.(2010). A Systematic Review on the Sambuci fructus. Effect and Efficacy Profiles. Phytother. Res. 24: 1–8