Another school of thought - more than Oxalates, it is that high percentages of unprotected supplement minerals are crystalizing in the small intestines and becoming useless.

I learned this from a research and development division of a wellness manufacturer who founded a patented fix (two in fact) to the problem that caused up to ten times higher absorption of minerals.

You researchers will like reading about this - search for Oligo Technology introduced in 2008. Trust detail: when they discovered a fix, they threw away over $10 million supplements saying they could not in integrity sell a problem when there was a fix for it. (They had tested 250 name brand supplements and all had this crystalizing problem.)