I was randomly looking over some clinical trials the other day, and ran across this one:
The Absorption of Magnesium Oxide Compared to Citrate in Healthy Subjects
with abstract results here:
The study was a little odd, as you'd think they'd use equivalent doses, but they didn't. Unless I read it wrong, the mag ox people got 520mg/day, while the mag citrate people got 295.8mg/day. Their final results indicate mag ox resulted in greater Mg concentrations and a better reduction in cholesterol numbers.
It could be as simple as citrate does absorb better, but not that much better. But since mag oxide is dirt cheap, it's not that difficult to simply take a little more if you want to.
I know some people have thrown out that 4% absorption number in the past, but that won't apply if you have acid in your belly, which everyone does (or should). So are there any negatives associated with magnesium oxide other than possibly less absorption? I have read that perhaps there could be more free radicals formed when using this form, but not sure if there is any science behind that... or if it even matters.
I'm primarily curious as I got a package of free mag ox samples, and was wondering why not simply take this form, seeing as it's super cheap? It agrees with my belly more than citrates/malates do, and is a lot cheaper than mag lactate, which is very stomach friendly, but also very expensive.