Phytate, also known as phytic acid or inositol hexaphosphate (IP6), is a naturally occurring compound found within various plant-based foods. It functions as the primary storage form of phosphorus in plant tissues, particularly in seeds, grains, legumes, and nuts.
Phytate’s Role in Nutrient Absorption
Phytate binds to essential dietary minerals in the digestive tract, forming stable, insoluble complexes with metallic cations such as iron, zinc, calcium, and magnesium. This binding significantly reduces the bioavailability and absorption of these minerals.
The pH levels in the small intestine can increase the formation of these phytate-mineral complexes, causing them to precipitate and become less available for absorption. For individuals consuming diets rich in phytate-containing foods, especially those on predominantly plant-based diets without proper food preparation, this can lead to concerns about mineral deficiencies over time. While humans produce some phytase, an enzyme capable of breaking down phytate and releasing its bound minerals, the activity of this enzyme in the human digestive system is limited.
Beyond Antinutrient: Potential Health Benefits
Despite its impact on mineral absorption, phytate also possesses several beneficial biological activities. It exhibits antioxidant properties, which can help combat harmful free radicals in the body. This antioxidant capacity may play a role in reducing low-grade inflammation.
Research indicates phytate’s potential in disease prevention, including its association with a reduced risk of certain cancers, such as colon, breast, and prostate cancers. It has been shown to inhibit the growth of various cancerous cell lines and may even promote the differentiation of malignant cells, encouraging them to behave more like normal cells. Phytate has also been linked to preventing kidney stone formation by inhibiting calcium salt crystallization. Furthermore, it may contribute to blood sugar regulation, offering potential benefits for individuals with conditions like type II diabetes mellitus.
Reducing Phytate Content in Foods
Several practical methods can effectively reduce phytate levels in plant-based foods, enhancing mineral availability. Soaking grains and legumes in warm water, often with an acidic medium like lemon juice or vinegar, can activate naturally occurring phytase enzymes and leach out some phytic acid. Soaking times can vary, but typically range from 8 to 24 hours, with longer durations generally leading to greater reduction.
Sprouting involves soaking and germinating grains or seeds, which significantly activates phytase, breaking down phytate content by 37% to 81% in various grains and legumes. This process not only reduces phytate but also can increase the overall nutrient content. Fermentation, as seen in sourdough bread or fermented legumes, is another highly effective method, potentially reducing phytic acid by up to 90% under optimal conditions, such as a pH of 4.5 and temperatures between 45° and 55°C. Cooking methods, particularly boiling, can also contribute to reducing phytic acid, though typically to a lesser extent, around 20%. Combining these methods, such as soaking followed by cooking or sprouting and then fermenting, can further enhance phytate degradation and improve nutrient absorption.