Soak your grains, seeds and legumes

Phytic acid is naturally present in the grains of many cereals (rice, wheat, oat, ...) and legumes (beans, lentils, chick peas, ...). It is found in the outer part of the grains (the bran f.i.).

"Phytic acid in grains and legumes interferes with the assimilation of their minerals, especially zinc."(1) This means that if you eat foods containing minerals but also phytic acid, a significant part of the minerals consumed will be of no use to your body. They will bind with the phytic acid, forming salts which are indigestible, and leave your body again without being absorbed.

Now this seems a bit tricky.
The very great majority of the minerals in grains and legumes is present in the outer part; but so is the phytic acid, its "ennemy". This means that if you take away the outer part, you get rid of the phytic acid allright, but also of the minerals. You throw away the good with the bad, so that's no solution. It's what happens with white flour, white bread, pasta and so on... Much less phytic acid, but also: much less minerals.
But if you retain the outer part (as in brown rice, brown bread, whole-grain pasta etcetera), you retain the minerals, but also the phytic acid - and so the minerals will not be well assimilated, you will not profit well from them either. So that's no solution either!

Luckily, there is a solution, and a very simple one: soaking! "Presoak grains and legumes before cooking to neutralize their phytic acid content, which otherwise binds the zinc, magnesium calcium and other minerals in these foods."(2) "Soaking removes phytic acid (...)."(3)

"Soak legumes for 12 hours or overnight in four parts water to one part legume. For best results, change the water once or twice. Lentils and whole dried peas require shorter soaking, while soybeans and garbanzos need to soak longer. Soaking softens skins and begins the sprouting process, which eliminates phytic acid, thereby making more minerals available. (...) Be sure to discard the soak water."(4)
And for cereals like whole rice, the process is similar.

So for the home kitchen, all is well. But what about store-bought foods? Are oats soaked before they're turned into flakes? And cornflakes? And any other breakfast cereal? Rice cakes?
No need to get paranoid - paranoia also inhibits assimilation of minerals :) - but it does put health claims on packaging and advertisments in another perspective.

If you are told that a breakfast cereal is full of minerals, that may be so, that's no lie - but it may be only half of the truth. Because it also may be full of phytic acid, so to speak, and the assimilation of these minerals into your body will be very low... So although a lot of minerals pass through your mouth, very few of them will actually get to your cells, to your blood in a useful way - and that's what counts eventually.

Footnotes:
(1) Paul Pitchford, "Healing with Whole Foods: Asian Traditions and Modern Nutrition", North Atlantic Books; 3rd edition (2002), p. 272
(2) id., p. 225
(3) id., p. 272
(4) id., pp. 512-513