The information about phytic acid is not true.
Phytic acid, unequivocally, does not exist in plants. Its just not there. Its too strong of an acid to even be there.
What does exist in grains and legumes is calcium magnesium phytate. A poorly soluble compound in which phytic acids acidity has been fully neutralized by both calcium and magnesium. Calcium magnesium phytate will not 'steal' minerals from your food because its already neutralized.
The mistaken notion from 100 years ago was that the phytate will hold on to the calcium and magnesium that it carries with itself and thereby not be a source of calcium or magnesium. That assumption was put to the test and disproven before my grandfather was born and, indeed, my medical books from the 1950's confirm that calcium magnesium phytate was an approved dietary calcium supplement!
The phytate does hold on to its minerals fairly well, stomach acid can free some up (thats why it was a supplement in the 50's) but soaking grains or legumes before cooking will free up more. See, the stuff is there for a reason, its a storage form of calcium and magnesium for the seeds. Plants dont have bones so they hide extra minerals there. When soaked the seed wakes up and produces enzymes that begin breaking down the phosphate groups in the phytate, thus freeing minerals for the seedling.
Phytate is also an antioxidant and research is just beginning to understand how it feeds and stimulates healthy gut bacteria, particularly how the partially dephosphorylated phytate derivatives effect those critters. It shouldnt be any surprise, my dusty old medical books also confirm that microbiologists were using calcium magnesium phytate as a nutrient in the culture of bacteria and yeasts.
So, yeah, lots of big words there. The take home message is that phytate is yummy mineraly goodness and not the boogie man that paleo types make it out to be. They just dont want to admit there are nutrients that arent in meat.