Phosphorus is stored in plant-based foods as phytic acid. When phytic acid binds to other minerals such as manganese, zinc or iron, the two form a compound known as a phytate. Because humans don't have the enzymes needed to break down phytates, as much as 50 percent of these minerals -- especially iron -- passes out of the body unabsorbed. Phytic acid can offer some health benefits, however -- a high intake may lower your risk of heart disease, diabetes, cancer and kidney stones. Knowing how to maximize the nutrition you receive from foods rich in phytic acid can help.
Variety of Nuts
Nuts are one of the richest natural sources of phytic acid. Almonds can contain up to 9.4 grams of phytic acid in every 100 grams, while walnuts may supply up to 6.7 grams and cashews almost 5 grams. Toasting nuts before eating them can increase the amount of minerals you absorb since heat inactivates phytic acid. Initially soaking the nuts can also decrease the phytic acid concentration, as can eating the nuts with a food that's high in vitamin C, such as strawberries or oranges.
Whole, Not Refined Grains
Whole grains contain a far higher concentration of phytic acid than refined grains since most of the phytic acid in cereal grains is found within the outer bran layer. Wheat bran contains up to 7.3 grams of phytates in 100 grams and rice bran 2.6 to 8.7 grams. Oats, barley and wild rice supply amounts ranging from 0.4 to 2.2 grams per 100 grams of the food. Presoak the grains to lower the phytic acid, or prepare them with a source of yeast, such as in bread.
High Concentration in Seeds
Approximately 7 percent of the dry weight of seeds is contributed by phytic acid, says nutritionist Dr. Mike Roussell on the Shape website. Examples include sesame seeds, which have 1.4 to 5.4 grams of phytic acid in every 100 grams, linseed, flax seed, rape seed and sunflower seed kernels. Soybeans fall into this category because they are the seed of the soy plant. The beans themselves have 1 to 2.2 grams of phytic acid in 100 grams, while tofu has up to 3 grams of the compound. Soak, then dry-toast or roast the seeds as you would nuts.
All Types of Beans
Kidney, pinto, black and navy beans may contain as much as 2.4 grams of phytic acid in every 100 grams. Dry cowpeas can supply nearly 3 grams per 100 grams of the legumes, and broad beans may have between 0.51 and 1.7 grams. To get the biggest reduction in phytic acid per serving, nutrition author Amanda Rose recommends covering dried beans with warm water, then soaking them in a warm spot overnight before cooking. Consuming the beans with a small amount of meat, fish or poultry will also increase the amount of minerals you absorb from cooked beans.
- Precision Nutrition: All About Phytates (Phytic Acid)
- Linus Pauling Institute: Iron
- Molecular Nutrition & Food Research: Phytate in Foods and Significance for Humans - Food Sources, Intake, Processing, Bioavailability, Protective Role and Analysis
- Phytic Acid: Soaking Beans
- Shape: Ask the Diet Doctor - Should I Soak Nuts, Seeds and Grains?
- Journal of Food Science and Technology: Reduction of Phytic Acid and Enhancement of Bioavailable Micronutrients in Food Grains