Elderberry

Elderberry refers to the berries of Sambucus species, most often the European black elder (Sambucus nigra), a shrub or small tree of the family Adoxaceae native to Europe and parts of Asia and North Africa. The ripe, cooked berries are used to make syrups, juices, wines, jams, and supplements; raw berries, along with the plant's leaves, bark, and seeds, contain cyanogenic compounds and can cause nausea if consumed uncooked.

The berries are a rich source of anthocyanins, the pigments responsible for their deep color, along with other flavonoids and phenolic acids that give the fruit strong antioxidant activity in laboratory tests. These polyphenols, together with possible direct effects on viruses, have been proposed to account for any benefit against respiratory infections.

Elderberry is used mainly to prevent or shorten the common cold and influenza, but the clinical evidence is genuinely mixed. A meta-analysis of randomized trials concluded that elderberry supplementation substantially reduced upper-respiratory symptoms, with a larger effect suggested for influenza ^[1], and a controlled trial in air travelers found that a standardized extract shortened the duration and lessened the severity of colds compared with placebo ^[2]. Other work has been less encouraging: a randomized, placebo-controlled trial in emergency-room patients with laboratory-confirmed influenza found no reduction in the duration or severity of illness ^[3]. Larger and more rigorous studies have been called for.

Elderberry is sold as syrups, gummies, capsules, lozenges, and teas and is regulated as a dietary supplement rather than an approved drug. It is generally considered safe when the fruit is properly ripened and cooked ^[1][2].

Cooked or properly prepared elderberry is safe for most people; raw berries, leaves, and stems contain compounds that can cause nausea and vomiting, so commercial cooked products are the way to go. Side effects from finished products are uncommon and mild. There's a theoretical caution around immune-stimulating effects in autoimmune conditions, though it's rarely an issue in practice.