Have you tried an anti-oxidant like pycnogenols? (i.e. pine bark, grape seed extract, etc.).....I know that I'm taking an anti-oxidant which contains pine bark, grape seed extract, blue-green algae and 10 other anti-oxidant nutrients and I haven't had the flue in 18 months (about the time I began this product). I also used to have sinus infections AT LEAST every time the seasons changed....I have had only two sinus infections and this product cleared them both up! Mark