"Will cooking rice reduce the phytic acid? Should I soak it before I cook it?"
I get this question fairly regularly and some inquisitive Googlers have landed here with this question.
If you've never heard of phytic acid, the reason the question comes up is that all grains, legumes, nuts, and seeds contain phytic acid (phytates) which bind to minerals in those foods and limit our digestion of the minerals. There are preparation techniques for reducing phytic acid. One key technique is soaking the food before cooking it.
So the question is: Does rice have a high phytic acid content and is it necessary to soak it?
Whole grain rice (brown rice) does contain phytic acid.
A 2007 study in the Journal of the Science of Food and Agriculture studied rice varieties in China. Across the vast lands of China, different rice varieties created a whole grain food that varied in iron, zinc, and phytic acid. Some varieties had high levels of minerals and lower levels of phytic acid, some had lower mineral levels and higher phytic acid. But the conclusion of the researchers is interesting for our purposes:
"The bioavailability of Fe [iron] and Zn [zinc] is very low because of the presence of phytic acid, even in rice varieties with the lowest levels of PA [phytic acid] and highest levels of Fe and Zn."
They recommend cultivating rice varieties lower in phytic acid but also "post harvest processing methods" to reduce phytic acid levels.
Our kitchens are miniature food processing plants. What you can do to reduce the phytic acid in your rice is to follow the soaking instructions I list on the grain soaking page. Basically, you will soak your rice before cooking. Your cooking time will likely be lower and, by how much, I am not yet sure. I eat almost no rice so I will have to buy some to experiment. In the meantime, if you try a pre-soak and want to share your experience, post your comments on this post.
Keep in mind that this study comes from China where the population depends on rice for zinc and iron intake. If you are not struggling with a deficiency in zinc, iron, calcium, or magnesium (all bound by phytic acid) and with other sources of zinc and iron in your diet (notably meat sources), you do not need to worry as much about phytic acid in rice.
By the way, the white rice you eat with your sushi doesn't need to be soaked. It's very low in phytic acid and lost about 80% of its minerals when processors scraped off the brown part.
