Dietary Supplement Sambucus Extract Gluten-Free Soy-Free LaB Verified Discussion: Solaray Black Elderberry Juice supplement is a superior form or European Black Elderberry (Sambucus nigra). This unique Elderberry Juice contains key actives; polyphenols and plant proteins called lectins. Elderberry naturally contains other important components, including rutin, anthocyanins and quercetin.