Using this product alone, for me, was and still is virtually ineffective. The amount of Zinc and Vitamin C and Vitamin D3 support that is needed pretty much eliminates Resistol except as a supplement to the Zinc and Vitamin C and Vitamin D3. I figure I only got maybe an extra 10% of resistance with Resistol, certainly no higher than roughly 15% at best guess. For an advertised up to 50% white blood cell increase that never happened with me, Resistol to me is not enough of a help to recommend. I did not get near the benefit I hoped. Sorry.