The plant kingdom, however, is highly dependent on phytic acid to protect seeds against insects, mold and fungus, and to preserve freshness for germination. It is the main storage form of phosphorous in many plant tissues, yet up to 80% of the phosphorous is locked in an unusable form as phytate.
In humans and animals with a single stomach, the small amount of phytase produced- the enzyme which breaks down phytic acid- means a limited ability to break apart the tightly bound phosphorus, making it mostly unavailable for absorption.
There is also a risk of losing calcium, as the body sends this mineral to bind with phytic acid when it is prevalent in the diet. Along with other minerals, calcium, magnesium, iron and zinc tend to be bound to phosphorous as phytates. Once bound, they are then eliminated from the body. This is of particular concern for humans because phosphorous and calcium are key minerals for bone and tooth health. Furthermore, phytic acid inhibits enzymes that are needed to break down food, such as pepsin to digest proteins and amylase to digest complex sugars.
Phytic Acid in Nuts, Grains and Seeds
Phytic acid presents a challenge for those consuming large quantities of grains, legumes, nuts and seeds, since it is most concentrated in these foods. Commercial whole-wheat bread and all-bran cereals, because they are unrefined and therefore retain most of the wheat’s nutrients in the outer layers of the seeds, are especially high in phytates.
In general, nuts contain levels of phytic acid equal to or higher than those of grains. Those consuming peanut butter, nut butters or nut flours, will take in phytate levels similar to those in unsoaked grains. Raw unfermented cacao and normal cooked cacao powders, popular ingredients in many raw food desserts, are also extremely high in phytates. While exact levels will vary, phytic acid tends to be significantly higher in crops grown with the use of modern high-phosphate fertilizers than those grown in natural compost.
Studies suggest that minerals are much better absorbed from our food when phytate is absent or minimal.
How to ensure that our intake is as low as possible?
By keeping a diet which is well-balanced with fruits and vegetables and nuts, seeds and grains are kept to a minimum. With the exception of a small handful of specific foods, fruits and vegetables are naturally very low in phytates. They are also naturally plentiful in vitamin C, allowing for better iron absorption in the presence of phytates.
If and when high-phytate foods are to be eaten, soaking and sprouting are effective methods to reduce the phytic acid content and therefore release a greater portion of the vitamins and minerals, although phytates cannot be entirely eliminated. Sprouted grains should also be soaked for several hours and then cooked.
Any seeds, nuts and nut butters should be soaked or made with soaked nuts for the same reason. While humans produce very little phytase to counteract large amounts of high-phytate foods eaten on a regular basis, several strands of digestive microflora can produce phytase. Therefore, fostering an internal environment that is conducive to healthy gut flora is important. Abstaining from antibiotics and antimicrobial foods, while emphasizing plenty of fruits and vegetables, among other good habits, can contribute to an ideal environment for symbiotic bacteria to flourish.
While most research has demonstrated that phytate is an antinutrient, beneficial properties have also been found. Phytates have been linked to anti-cancer activity in the presence of tumor cells, to reducing cholesterol and keeping blood sugar in check. Of course, Nature is much more complex than science often makes it out to be, and a negative or positive effect can never be attributed solely to one specific nutrient.
What is clear, however, is that increasing the amount of raw fruits and vegetables in our diets will ensure a decreased phytate intake,
thus increasing our odds of absorbing and utilizing other important nutrients.
Furthermore, as complete nutrient-dense, water-rich foods, they will also provide us with a much wider array of healthful benefits.
By Karen Ranzi, M.A.
- Proximate Composition and Mineral and Phytate Contents of Legumes Grown in Sudan. Journal of Food Composition and Analysis 1989 2:69-78.
- Malleshi NG. Nutritive value of malted millet flours. Plant Foods for Human Nutrition 1986 36:191-6.
- Inhibitory effect of nuts on iron absorption. American Journal of Clinical Nutrition 1988 47:270-4.