No, magnesium is not appreciably absorbed from mag oxide.
8mg/400mg dose is negligible.
The chelates give better absorption from studies, but DOSE is also a factor. Take enough of a chelate and it will be laxative too.
Based on the study I put up here, 1500mg of mag oxide would yield about 30mg absorbable magnesium (if it weren't somehow lessened by the increased motility it caused). 30mg is about 1/10 of the RDA.
Don't forget you must account for elemental values. 400mg of mag ox is about 50% mag and only 4 % of that is absorbed under ideal conditions.
So magnesium oxide is in the Laxative called Phillips caplets:
http://phillipsrelief.com/caplets.html
Magnesium citrate taken in large amounts is also laxative, and has been used that way for decades. That Citrate of Magnesia bottle is totally consumed for that effect.
http://www.allegromedical.com/otc-me...19e33618e01127
TEN ounces all at once!
While you are looking only for laxative action, what are you doing for your supplement needs? It is this that confuses me about your post.
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All truths are easy to understand once they are discovered; the point is to discover them.-- Galileo Galilei
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Weezie looking at petunias 8.25.2017
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