For me, Colloidal Silver was too weak for my candida. But then again I probably did not take enough of it. Colloidal Gold too. Combination with iodine, borax was the thing that took care of my candida.
Iodine does not kill the gut flora; we have members at the board making yoghurt batches with / without iodine; no difference between it. Have a search if you like. I also made bread with iodine; like they did in the 60th ies; Iodine does not kill yeast cells.
-And my gut flora was a mess since an Antibiotic over 20 years ago, candida etc followed. Now healed, after Iodine etc.
When it comes to gold and silver; gold leafs is better IMO, I use Colloidal Silver for my carbonated water and ice cube machine.