I think they compete with one-another and can displace the other, hence why there is sometimes a worsening of symptoms when a mercury toxic person uses selenium. Best to start with a low dose. Selenium methionine is apparently a better tolerated form of selenium.

When I was very obviously mercury toxic, I found selenium very effective, sometimes too much so. I had to take breaks and/or reduce the dose at times to cope with the symptoms.

Ones that I found effective were also vitamin C (powder form containing bioflavanoids) and natural vitamin E.

Just they alone did much to increase my antioxidant power and in doing so, precipitated a certain amount of mercury mobilisation/detox.

Some do find chlorella helpful. However, it can be devastating also. I've used it when very metal toxic and wound up on the floor between my bed and the wall in a crying heap. Just from such severe mobilisation/redistribution. It's not a place to be! The same thing happened when I used an isolated dose of DMSA without using it frequently as Cutler points out.

So it's very much an individual thing.