@kmkam the wonderful @primek gave me this amazing site and would urge you to explore it. I have found it endlessly useful and worthwhile.Like you I am a natural supplements fan but not all are safe for everyone in all circumstances. It originates from a Cancer hospital in NYC which amongst other things thoroughly researches natural supplements and here is their web address
www.mskcc.org/cancer-care/patient-education/herbal-remedies-and-treatment ;
It is not only about herbs but includes vitamins and minerals nor is it only about their impact on cancer.This site is recommended by BCNA.
But please also check things out with your oncologist/GP if in doubt.