All About Phytates (Phytic Acid)
By Ryan Andrews
Phytic acid – the storage form of phosphorus – is one of those pesky “anti-nutrients” the Paleo community keeps telling you to avoid.
It’s often considered an anti-nutrient because it binds minerals in the digestive tract, making them less available to our bodies.
Yet these same anti-nutrient properties can also help in the prevention of chronic disease.
What is phytic acid?
Seeds — such as nuts, edible seeds, beans/legumes, and grains — store phosphorus as phytic acid. When phytic acid is bound to a mineral in the seed, it’s known as phytate.
The tables below compare various seed types according to their phytic acid/phytate content.
As you can see, phytic acid content varies greatly among plants. This is due to the type of seed, environmental condition, climate, soil quality, how phytate is measured in the lab, and so forth.
Roots, tubers, and other vegetables may also contain phytic acid, but usually in lower amounts.
The most concentrated sources tend to be whole grains and beans. Phytic acid is isolated in the aleurone layer in most grains, making it more concentrated in the bran. In legumes, it’s found in the cotyledon layer (where the protein is).
When we eat the plant, phytates are hydrolyzed during digestion to myo-inositol-1,2,3,4,5,6-hexkisphosphate (IP6) and lower inositol polyphosphates including IP1 through IP5 (these are phytate degradation products).
Who’s eating phytic acid?
Everyone who eats plants consumes some phytic acid. It’s all a question of degree.
As you can imagine, intake tends to be much higher among those who follow non-Westernized diets. In developing countries, plants are staple foods, which means people eat more of them, and therefore get more phytic acid.
In developed countries, plant-based or vegetarian eaters tend to consume more phytic acid than omnivores. Further, males usually consume more phytic acid than females, simply because they eat more food.
Most phytate (37-66%) is degraded in the stomach and small intestines.
Ordinarily, our bodies regulate phytate levels pretty well, adjusting uptake in the gut and excretion until body levels come into balance.
Vitamin D status in the body seems to influence how much phytate is actually retained. The more vitamin D, the more phytate retained; the less vitamin D, the less phytate retained.
Potential problems with phytic acid
Phytic acid can bind minerals in the gut before they are absorbed and influence digestive enzymes. Phytates also reduce the digestibility of starches, proteins, and fats.
Here’s an example.
Vegan eaters often consume more iron than omnivores. Yet, they also consume more anti-nutrients, including phytates, and these reduce the amount of iron available to their bodies. Consuming 5-10 mg of phytic acid can reduce iron absorption by 50%.
This is why vegetarian eaters should eat more iron than omnivores (33 mg for veg eaters vs. 18 mg for omnivores).
- Adult men lose ~1 mg of iron per day
- Adult menstruating women lose ~1.4 mg/day
- Postmenopausal women lose ~0.8 mg/day
- Lactating women lose ~1.1 mg/day
While in the intestines, phytic acid can bind the minerals iron, zinc, and manganese. Once bound, they are then excreted in waste.
This can be a good or bad thing, depending on the condition. It’s a bad thing if you’re having trouble building up iron stores in the body and have developed iron-deficiency anemia.
When is it a good thing? Keep reading – you’ll find potential benefits of phytic acid below.
Potential benefits of phytic acid
Despite its potential drawbacks, phytic acid is similar in some ways to a vitamin, and metabolites of phytic acid may have secondary messenger roles in cells.
Some experts even suggest that it’s the phytic acid in whole grains and beans that lends them their apparent protective properties against cardiovascular disease, cancer, and diabetes.
(Remember, the grains with little to no phytic acid are the refined ones.)
The supplement industry has caught on to this. Have you even seen a bottle of inositol hexaphosphate, or IP6? …read more
Read more here: Precision Nutrition