High selenium yeast can promote the further growth of biofilms (candidiasis). That's the primary problem of amalgams, they're antibacterial, and there's the very beginning of the problems caused by the metals they leech.
However, the right forms of selenium prove quite beneficial.
I chose to use selenoExcell (high selenium yeast) some 3-4 years ago while I still had my Amalgams in, and experienced the problem of fading color vision.
From reading around, it's a lack of sulfur-metabolites that creates the damaging effects of taking unconjugated (selenium that's not bound with sulfur compounds) elemental selenium.
There are posts in Newport's posting history explaining that methyl groups and methionine groups (sulfur compounds) help reduce and recycle homocysteine groups in the liver. He promotes the use of tri-methyl-gycine (an active ingredient in fresh-pressed beetroot juice, mark you, /not/ betain HCL), which is marketed by Jarrow products as TMG. He reports using it in quantities up to 3g per day, as some athletes do.
Further posts report folk who have quite negative reactions to selenium supplementation perking right up again when using it together with ti-methyl-glycine. (also, that TMG is more active than SAM-e, a very expensive meat extract which contains two methyl groups instead of one. )
Naturehackerproducts (that guy. you can find his page if you google that name), offers selenium by a completely different tactic- supplying a lot of free-floating methionine and elemental selenium in dropper form.
Basically the detrimental effects of supplementing selenium happens when there's not enough methyl-donors in circulation in the body to complete the processes it triggers in the cells.
And yes, my eyesight is plenty recovered. There's nothing in this life that doesn't run in a cycle, and even if you screw up, you still pick up the ball again later.
Selenium supplements I've fond helpful:
I've used - Solaray 100mg with powdered pumpkin seed for the cofactors)
- nature's way 200mg
methyl-seleno-cysteine (cysteine groups are another sulfur-compound that are a precursor to glutathione peroxidase)
- Vitamin research products 200mcg
- jarrow formulas selenium synergy (both types +b2 and E for cofactors)
Ones I'm not touching:
- healthy origins selenoexcell (not without a bucket of methionine powder :p )
- life extension super-selenium-complex (again, sodium selenite without extra methionines)
Newport and others report a tiny amount of soldium selenite being beneficial in their supplemental regimes, though you're looking at upping your health after amalgams.. welp. There ya good :)