Elderberry contains Vitamins A, B and C, amino acids, carotenoids, tannins and flavonoids. It may also be effective as an immune system stimulant, diuretic, anti-.inflammatory. Studies have indicated that it is a very effective antiviral agent. When taken during the first 48 hours the flu, two separate studies showed that it inhibited the effects of the virus. Participants experienced a noticeable reduction in the duration of their symptoms. Elderberry also is known to possess the antioxidants called flavonoids. Antioxidants may help fight off multiple sclerosis, vascular diseases, degenerative diseases, cancer and cardiovascular diseases. Antioxidants are known to scavenge free radicals and help reduce oxidative stress. This makes elderberry a valuable tool to help prevent certain diseases.