Veg.diet and phytic acid

My teenaged daughter recently had a routine blood test which revealed potassium and magnesium levels in the low end of normal. She is an ovo-lacto vegetarian and usually eats well. She has increased her intake of nuts, beans, and whole grains - foods that provide both potassium and magnesium. I have recently become aware that these foods contain phytic acid, which can prevent the absorption of minerals. May questions are as follows:
1) Does phytic acid prevent the absorption of potassium or just magnesium, iron and calcium?
2) Do processed foods like pre-packaged oatmeal and canned beans have the phytic acid content reduced/eliminated by processing? Would it be better to use the home soaking and cooking method to remove the phytic acid?
3 Will eating phytic acid containing foods interfere with OTC mineral supplements? Should you take them hours before eating?

[Renee Radenberg]

Phytic acid or phytate is the principal storage of phosphorus in plant tissues (mainly bran and seeds). It can decrease the absorption of the minerals iron, potassium, magnesium and calcium, however, eating a variety of foods help the minerals to be absorbed.  For example Iron absorption is increased due to Vitamin C lowering the effect of Phytic acid. The longer you cook the food (beans, legumes, and whole grains), the more you destroy the Phytic acid. Processed foods already have some of it destroyed due to the processing method. Eating a variety of foods at all meals will insure that all vitamins and minerals will be absorbed. Recommendations for Calcium supplementation should be taken with meals; and Iron needs Vitamin C foods eaten at the same time. Hoped this helped.