Sambucol Immuno Forte Effervescent contains Black Elderberry with naturally occurring flavonoids plus Vitamin C and Zinc which contributes to the normal function of the immune system and protection of cells from oxidative stress. Sambucol is the product of over 25 years of scientific research, making it the most extensively researched Black Elderberry vitamin in the world. Sambucol is the original Black Elderberry brand developed in 1991. Sambucol was founded on the plant-based properties of Black Elderberry (Sambucus nigra) using a preparation method that helps preserve the rich, phytonutrient flavonoids (anthocyanins) present in the Black Elderberries to maintain its natural effect.