MSM can mobilise mercury, but it's the body's job to eliminate it. The mercury just gets stirred up and this is why some mercury toxic people can be quite intolerant to sulfur foods/products.

However, some do very well on sulfur (those low in it). It can be really helpful in that case. But if you find it causing too many symptoms? it maybe that you are high in sulfur already and the extra is simply shifting too much mercury around for your body to cope with.

When I was very high in mercury (body), I found that I reacted very strongly and sometimes quite intolerably to sulfur foods like onions/garlic/cabbage/eggs etc. Chlorella was even worse (far worse). My symptoms were unmanageable. This is why I had to cut down on the sulfur until enough mercury was removed for me to tolerate it again. So yeah, it can definitely move mercury around.