Phytic acid in sourdough bread vs. yeast bread

The previous article was about phytic acid in grains and legumes: how it inhibits assimilation of minerals in the body, and how soaking resolves the problem.

But how about bread? In brown bread the bran is still present - and so we get back to the problem of the phytic acid: if the phytic acid present in the bran is not broken down, the minerals will not be well assimilated. And in the case of bread soaking is not an option, because it is impossible (or very impractical at least) to soak grains before grinding them into flour.

Luckily, again, the solution is very simple: sourdough!
Here is what Wikipedia has to say about it: "Natural sourdough fermentation (without yeast) is slow and creates an acid environment (pH below 5.5) that activates enzymes, called phytase, that are present in the flour."(1) "Phytase is an enzyme that can break down the undigestible phytic acid (phytate) part found in grains and oil seeds and thus release digestible phosphorus, calcium and other nutrients."(2)
And Paul Pitchford: "[In sourdough bread] the natural bacterial action and baking neutralize nearly all of the phytic acid which occurs in wheat and other grains. (Phytic acid reduces mineral metabolism - especially in those whose diet includes a good percentage of grains and legumes - and can contribute to anemia, nervous disorders, and rickets.)"(3)

However, "about 90% of the phytic acid remains in yeasted breads"(4). So even if it contains a lot of minerals, as in brown yeast bread, you will profit very little of them.

This doesn't mean you should prefer white yeast bread over brown yeast bread. Brown yeast bread still contains other things which are beneficial, like fiber, and which white bread doesn't contain. And even with the phytic acid, you still assimilate more minerals from brown yeast bread than from white yeast bread, it seems.

But compared to sourdough bread, the mineral uptake from yeast bread is very low...

(By the way, the same problem occurs with "a diet rich in whole-grain noodles": "the phytic acid they contain [...] tends to bind minerals in the body. Of course, this problem is neutralized in a sourdough process, and so the home noodle-maker should use such a natural leavening process."(5))

Footnotes:
(1) "Acide phytique", Wikipedia, translated by me.
(2) "Phytase", Wikipedia
(3, 4) Paul Pitchford, "Healing with Whole Foods: Asian Traditions and Modern Nutrition", North Atlantic Books; 3rd edition (2002), p. 492
(5) id. p. 484