Tuesday, 15 April 2014

Foods High in Phytates

by Sandi Busch
Sprouting reduces phytate while retaining nutrients.
Sprouting reduces phytate while retaining nutrients.
Phytate has been dubbed the anti-nutrient, but it’s also a beneficial phytonutrient. Phytate binds with minerals and prevents their absorption, possibly leading to deficiencies, especially if your diet is high in fiber and whole-grain foods. It’s also an antioxidant and may help fight some cancers. Maintain a balance by monitoring your consumption of high-phytate foods and by getting enough of the nutrients affected by phytate.

Definition

Phytate is known by eight different names but the most common are phytic acid, inositol hexaphosphate and IP-6. Phytate is found in all plants because it stores the phosphorus needed to support germination and growth. An enzyme called phytase neutralizes the phytate to release the phosphorus. Plants and most animals have their own phytase. Unfortunately, humans don’t. Bacteria in the intestine produce small amounts, but not enough to digest phytate. The phytate then binds with iron, calcium and zinc, which means the minerals can’t be properly absorbed.

Grains

The amount of phytate you'll get from any food source varies depending on growing conditions and processing techniques. Measurements used to report phytate content are sometimes stated as a percentage of dry weight and other times as milligrams in a 100-gram portion. Regardless of these differences, you’ll find wheat bran, rice bran, whole wheat, corn, rye, oats and brown rice at the top of the list. Phytate is highest in bran-based products. Whole-wheat flour has about half the phytate of bran but double the amount in corn, oat, rice or processed white flours, according to the book "Food Phytates."

Beans and Nuts

You can count on beans and nuts to contain phytate, but the amount ranges from approximately .4 percent to as high as 2 to 3 percent of dry weight, according to "Food Phytates." Soy, pinto, kidney and navy beans, as well as peanuts, are at the high end. They have double the amount of phytate found in peas, lentils, chickpeas, white beans, walnuts and mung beans. Unlike grains that have a large concentration of phytate in the bran, phytate is equally distributed throughout seeds.

Potatoes

When dry weights are compared, potatoes have almost as much phytate as seeds, according to a study published in the April 2004 issue of the “Journal of Food Composition and Analysis.” Even though cooking typically eliminates some phytate, that’s not true in potatoes. Whether potatoes are baked, boiled, microwaved or fried, they retain virtually all of their phytate. Based on average consumption, the researchers noted that phytate consumed in cooked potatoes may account for a substantial portion of the average American’s daily intake of phytate.

Preparation

Some methods of commercial food processing destroy phytase, which means that the food retains more phytate. Other processes that actually reduce total phytate are soaking, fermenting and sprouting. Soaking rice, beans and raw nuts for 24 hours, followed by cooking them for the longest time possible, can reduce phytates by 50 percent, according to the Weston A. Price Foundation. When beans are sprouted, total phytate goes down by as much as 75 percent. Sprouting retains nutritional value, but the longer you soak and cook food, the more essential vitamins and minerals you’ll lose together with the phytate. Following recommended daily intakes should ensure you get sufficient nutrients, because the recommendations are adjusted for the possibility of substances such as phytates that impact bioavailability.


References

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