Phytic acid or phytate (when in salt form) is one of the many phytochemicals found in nature that are considered non-essential nutrients, meaning they’re not needed to sustain life. However, most non-essential plant chemicals, including phytic acid, can still have a significant impact on human health.
For plants, phytic acid is the predominant storage form of phosphorus and is considered a common plant antioxidant. Phytic acid is found in various quantities in soy, peanuts, whole grain cereals, rice, wheat and corn and products containing these foods. For humans, however, there’s mounting evidence that phytic acid is an anti-nutrient that binds with minerals such as iron, magnesium, calcium, and zinc, making them useless for the human body. At the same time, there’s a small body of research that phytic acid may have a few positive benefits, including acting as an antioxidant, an energy store, and an anti-inflammatory agent. Phytic acid is also thought to reduce the early onset of colon cancer. Yet, phytic acid’s action as an anti-nutrient appears to outweigh any of its potential benefits. Moreover, it’s high concentration in many important staple crops makes phytic acid an important health concern.
How Phytic Acid Binds to Minerals
Although vital in plants, in humans phytic acid’s phosphorus is not biologically available. Phytic acid is polyanionic (a molecule possessing multiple negative sites) due to the many phosphate groups. These negatively charged “arms” of the phytic acid molecule bind with important positively charged minerals in the body, especially calcium and zinc. When this happens, phytic acid is transformed into its salt form known as phytate. Once the surrounding minerals are bound to phytate they are rendered insoluble and cannot be absorbed by the digestive tract.
Ways to Minimize Phytic Acid Consumption
Does phytic acid’s effect on mineral absorption mean that were not meant to enjoy any foods containing phytic acid? Of course not! Apart from conveniences such as refrigerators and electric ovens were invented, people traditionally preserve and process their foods with methods that inadvertently reduce phytic acid content. The processing techniques commonly used include soaking and fermentation. These methods help render grains and seeds easier to cook and increase their storage life.
Through the soaking process, seeds and grains are soaked long enough (12 to 36 hours) to germinate and soften, which allows for faster cooking times (important if you don’t have access to a gas burner) and better digestion. What wasn’t known until recently, however was that soaking also activates a grain’s phytase content. Phytase is an enzyme that breaks down phytic acid!
Some grain and seeds, however, contain very little natural phytase (oat meal and rice for example), so simple soaking does very little to reduce phytic acid content. This is where lacto-fermentation comes in. During lacto-fermentation, seeds and grains are soaked long enough to allow beneficial bacteria to form (such as lactic acid bacteria), which keep harmful pathogens at bay and make foods safe to store at room temperature for long periods of time. The fermentation process can also encourage the growth of phytase producing bacteria that supply enough phytase to break down most of the phytic acid content in seeds and grains! In fact, lacto-fermentation is one of the traditional Chinese ways of preparing brown rice but has has recently gone out of practice (due to the invention of the rice cooker).
The take away: Phytic acid prevents the absorption of many of the minerals that make seeds and grains potentially healthy foods. Traditional, pre-industrial, ways of preparing these foods inadvertently made them more nutritious. Take the time to get the most out of your food an optimize your health by soaking all seeds (quinoa and beans) and grains for at least 12 hours. For rice and oatmeal, consider using lacto-fermentation.
Is Brown-Rice Toxic? It All Depends.
References: Top cultures. Phytochemicals. Gaetke, Gaetke LM, McClain CJ, Toleman CJ, Stuart MA. “Yogurt protects against growth retardation in weanling rats fed diets high in phytic acid.” J. Nutr. Biochem. 2010;21:147-152., Peng WU, Tao Z, Ji-chun T. “Phytic acid contents of wheat flours from different mill streams.” Agricultural Sciences in China. 2010;9:1684-1688., Nagel R. “Living With Phytic Acid.” Weston A. Price Foundation Website., Raghavendra P, Halami PM. “Screening, selection and characterization of phytic acid degrading lactic acid bacteria from chicken intestine.” International Journal of Food Microbiology. 2009;133:129-134., Lönnerdal B. “Soybean ferritin: implications for iron status of vegetarians.” Am J Clin Nutr. 2009;89:1680S–1685S.
Originally posted 2013-08-15 09:00:15.