This is the one brand I trust implicitly. I have my 5 (adult) kids on it and myself/husband, the immunihealth immune defense - we have been taking it for about 3 years now. I researched the ingredients and it just made sense, right doses, right combo. I rarely get sick now when taking it and if I do I bounce back super fast. Stopped taking it for a few months recently and wow, I wasn't well at all when I caught a thing going around, so started back on it straight away and within a day I was feeling better. Added the probiotic recently as my research also showed that they had a great combo of probiotics that were also quite good for my husband's MCAS too!