What is phytic acid? (All grains, seeds and nuts…)
Phytic acid: vitamin or anti-nutrient?
Phytic acid (known as inositol hexaphosphate (IP6), or phytate) is the principal storage form of phosphorus in many plant tissues, especially in the grass family (wheat, rice, rye, barley etc) and beans. Phosphorus in this form is generally not bioavailable to humans because humans lack the digestive enzyme, phytase, required to separate phosphorus from the phytate molecule.
Phytic acid binds to important minerals such as calcium, magnesium, iron and zinc and can therefore contribute to mineral deficiencies, as the minerals are not released from the phytate and are thus unavailable to the body. For people with a particularly low intake of essential minerals, especially young children and those in developing countries, this effect can be undesirable.
A common way in developing countries to increase the bioavailability of minerals from grains and beans is using fermentation. Many bacteria possess phytase activity and by fermenting grains or beans by lactic acid bacteria the phytate is destroyed and the bioavailability of the minerals is increased.
Phytic acid recently has been studied for its potential anti-carcinogenic properties. Recent studies have indicated that phytic acid may have some preventive effect in prostate, breast, pancreatic and colon cancer. The mechanism, however, is not yet understood.
Soybeans are high in phytic acid, present in the bran or hulls of all seeds. It’s a substance that can block the uptake of essential minerals – calcium, magnesium, copper, iron and especially zinc – in the intestinal tract.
Analysis shows that calcium, magnesium, iron and zinc are present in the plant foods eaten in these areas, but the high phytate content of soy- and grain-based diets prevents their absorption.
The soybean has one of the highest phytate levels of any grain or legume that has been studied,16 and the phytates in soy are highly resistant to normal phytate-reducing techniques such as long, slow cooking.17 Only a long period of fermentation will significantly reduce the phytate content of soybeans.
When precipitated soy products like tofu are consumed with meat, the mineral-blocking effects of the phytates are reduced.18 The Japanese traditionally eat a small amount of tofu or miso as part of a mineral-rich fish broth, followed by a serving of meat or fish.
Vegetarians who consume tofu and bean curd as a substitute for meat and dairy products risk severe mineral deficiencies. The results of calcium, magnesium and iron deficiency are well known; those of zinc are less so.