I just tell you what I've done, not that I feel totally researched...
My husband is taking yeast assassin and tummy tune up but I tried THREELAC for a few weeks (with results, but extreme die off reactions) and now only kefir with a whole- natural diet. For us a natural diet means only small amounts of succanat or evap. cane juice, honey, maple syrup, or sorghum molasses; whole grains; lots of garden veggies and fruit with homegrown meat and raw dairy products at home. We do occasionally eat out or accept invitations to other places. I do notice a setback if that includes refined and highly processed foods, but that is just part of life. I also do things to support effective cleansing and eliminations of toxins. Especially sufficient water consumption ie more than I think I can
In my opinion if you really have a serious, entrenched yeast problem it is best to be consistent with whatever you are using or doing or you might encourage a rebound effect or possibly allow the little buggers time to adjust. Does that make any sense? Like I said I'm just trying to figure out the yeast thing myself.
I chose not to use the yeast assassin because of the possibilities of problems if I should become pregnant. For example I would use wormwood for short periods in a parasite cleanse in pregnant goats but not for extended times. Similar concerns with other ing. in YA. My concern may be unfounded, but for now I just feel more comfortable with not using YA.
With all that said I do seem to be making HUGE progress with what I'm doing. My husband doesn't see as much progress, but also did NOT have as many or as severe symptoms. We can't really say what YA would have done for me.
Best wishes in your search for the wise course of action!!!!!!!!!
