I'm not sure why this happens Sean. I think perhaps the extra sulfur that the body doesn't need is then left available to mobilise mercury instead. Those who need it and use it more, may not get the same reactions...just a thought. If you respond well to garlic as well, as I think you said you did, then this emphasizes that you do well on sulfur. However, for some people with mercury, the reactions can be pretty horrible and long lasting. Food may not be "as bad", but supplements are usually in potent form and deliver it in a big dose.

Selenium can cause reactions too. But it is not a mobilising agent like chlorella. Andy realises some do not respond well to selenium and his suggestion is to try it in the form of selenomethione, which seems better tolerated or simply not take it at all if it continues to pose a problem. You can get natural selenium from certain foods and apparently garlic is one of them. So you maybe getting enough. I think brazil nuts are another one that contains it. Butter too? I have heard.

If it is not the form of selenium, it maybe the dose being too high. Also selenium tends to have a reaction with mercury, as in mercury displaces selenium. So replacing selenium may displace some mercury in the process and may precipitate a certain amount of detox reactions. I've had this myself and had to lower the dose or take a break. Certainly some forms of selenium maybe less tolerated for various reasons that I am unsure about. But dose/detox may also come into it.

Replacing antioxidants of any kind may well set off some detox responses. The antioxidant power of the body is increased, so that could be expected. Depends how readily available the mercury is too. I used to get reactions just by consuming a good quality vitamin C powder with bioflavanoids. That alone used to set off some metal detox. But it was very effective and long term, it was most helpful to me. I just had to take it easy at first and build up.