Phytic acid
Synonyms: inositol hexakisphosphate (IP6), phytate
The phytic acid, also known as inositol hexakisphosphate (IP6) or phytate, is present in all seeds and therefore in whole grain cereals, legumes and nuts (see table below).
Content of phytic acid in food
| Food | mg phytic acid per 100 g |
|---|---|
| Wheat bran | 3610 |
| Wheat germ | 1470 |
| Peanut | 1336 |
| Soybean seeds dried | 1250 |
| Barley, whole grain | 1070 |
| Rye, whole grain | 970 |
| Corn, whole grain | 940 |
| Wheat, whole grain | 906 |
| Oat, whole grain | 900 |
| Rice, whole grain | 890 |
| Bean seed, white, dried | 800 |
| Mung bean seed, dried | 629 |
| Quinoa | 541 |
| Chickpea seed, dried | 338 |
| Wholemeal wheaten bread | 330 |
| Chickpea seed, green | 280 |
| Rye bread | 250 |
| Rice | 240 |
| Pumpernickel | 100 |
| White bread | 20 |
| Banana | 20 |
| Avocado | 17 |
The phytic acid is mostly stored within the husks of the grain and provides the plant the necessary energy during germination.
In order to release this energy, the plant needs an enzyme called phytase, which liberates through germinating and soaking. This is the reason why e.g. bread dough should proved several hours - in this way the phytic acid is segregated and made harmless.
The average intake of phytic acid depends on the nutritional behavior and is about 0.3-3.0 g per day (Schlemmer 1995). In the gastro-intestinal tract, phytic acid can bind dietary minerals (like iron, calcium and zinc) under certain circumstances and decrease their absorption in the small intestine. This can lead to a lack of iron and zinc, especially in the developing countries.
In general, a normal nutrition with an average intake of phytic acid, as it is common in the industrial countries, does not affect the absorption of iron and zinc (National Research Council 1989).
Nowadays there also seem to be positive effects of phytic acid: it inhibits temporarily the enzyme amylase and therefore the conversion of starch to sugar and the rise of the blood glucose level can be significantly suppressed. Furthermore, anti-carcinogenic effects were observed in animal tests.