Soy Phytates

Plants store phosphorus, an essential nutrient for plants and animals, in their seeds to support the growth of young seedlings. This phosphorus is stored in the form of phytate (inositol hexametaphosphate). Plant phytates are considered by some to be “anti-nutrients” because phytates consumed in the human diet can complex with essential minerals like iron and zinc and inhibit absorption in the gut. Others, however, consider phytates to be important food constituents that act not only as natural food-preserving antioxidants, but also help reduce risk of heart disease and cancer in those who consume whole grains, beans, seeds and nuts.

Soybeans contain significant amounts of phytate (1.3-1.4%), and some point to this as a reason to avoid soy foods.  However, it is important to note that most whole grains, beans, seeds, and nuts are also rich in phytates (Table 1), and there is a wealth of science to support the fact that these foods are important constituents of a healthy, well-balanced diet that supports longevity and reduced disease risk. As such, it is difficult to argue that soy should be avoided based on its phytate content when so many healthy foods contain comparable levels of phytates.

It is also important to note that on a percent basis, isolated soy protein contains far less phytate than do whole soybeans.






Table 1.  Phytate contents of some common grains, beans, and nuts.  Values from NR Reddy and SK Sathe (eds).  Food Phytates.  CRC Press, 2001. 

Food	Phytate Content (%)
Whole Wheat	0.7-1.1
Wheat Flour	0.3-1.4
Wheat Bran	2.0-5.3
Corn	0.8-1.0
Oats	1.0
Barley	1.0
Brown Rice	0.9
Soybeans	1.3-1.4
Soy Protein Isolates	0.7-0.9
Kidney Beans	2.6-2.9
Lentils	0.4-0.5
Chick Peas	0.6
Small White Beans	1.2
Great Northern Beans	2.6-2.9
Peas	0.8-1.2
Hazel Nuts	1.9
Walnuts	0.6-2.4
Almonds	1.3-3.2
Cashews	0.6-2.0