Responsible supplementation by MR

I thought I'd direct you to an excellent post on supplementation by Michael, which can be found at the CRS lists. Here is a direct link to that post.
Responsible supplementation

I've only been taking 1/3 of the full dose of Essential mix for a while now, this was not long after some of his earlier posts on the issue... While I've taking some taking more targeted supplements like zinc, magnesium, vitamin D3, and Calcium especially. It seems for myself my Magnesium need is quite high, I don't know if this was to do with the amount of stress I had earlier this year or what. But I know it prevents quite a few symptoms I was having... One of them being benign heart palpitations (had all sorts of tests done - check earlier posts) from excess adrenaline, and also little annoying muscle twitches. When one is low on magnesium you do produce more adrenaline so it has an effect on the muscles, including the heart... These symptoms 98% cured by extra Mg, even though I was already getting around 500mg or so from my diet! Unfortunately as Michael says there are few reliable tests for mineral deficiencies, magnesium is one of them as it is mostly intracellular.

Take a read of that post anyway, it's a sensible view on supplementing.