Undecylenic acid and its zinc salt are used for the treatment and prevention of superficial fungus infections of the skin, primarily tinea pedis as well as relieves itching, burning and irritation.  We are talking about SYSTEMIC yeast.  I honestly have never had any success with capryllic acid, but I am not sure where you get your info that zinc undecylenic acid is 40x stronger than capryllic.  I wish it was that easy to take some zinc and get rid of yeast :)  How long have you suffered with yeast for?  You are right though, oil of Oregano is not in the same boat as the zinc you mention from castor beans, do a google search and you will see that castor beans are actually drifting at sea in a life boat compared to the well documented effects of oil of Oregano in VIVO studies.