BioSchwartz's natural formula contains 500 mg of elderberry fruit, 90 mg Vitamins C and 7.5 mg of zinc, all of which are great additions to any formula looking to boost immune health. There are no nasty fillers, but the formula lacks a lot of the ingredients that could make it stand out from the rest. They also have a 30-day return policy, which may not be enough time to tell whether or not the formula is right for you. All in all, Sambucus Elderberry earned the number 4 spot on our list.