I Have read that it is very very effective in protecting people from stomach bugs when travelling. I read ages ago of a study done in South America with two groups of tourists, one who had a drop of GSE every day and the other didn't and the results were spectacular, but I can't remember them exactly, except basically everyone or nearly everyone who didn't take it got sick and everyone or nearly who did take it didn't get sick.
I gave it to my hubby to take when he went to Africa last year and he didn't get sick at all. This isn't exactly conclusive evidence, but its not bad!!
I think its good stuff but it tastes HORRIBLE!!! I would put it in capsules if I were to take it now.