Phytase is an important enzyme that helps the body unlock essential minerals like iron, zinc, and calcium from plant-based foods. These minerals are often bound to phytic acid, or phytate, which is a major storage form of phosphorus in many plants. While phytic acid itself has antioxidant properties, its ability to bind minerals can be a concern, particularly for those on primarily plant-based diets. Activating the natural phytase in foods can significantly mitigate this effect.
Legumes
Legumes are excellent sources of naturally occurring phytase, which can be enhanced significantly through proper preparation. The phytic acid content in legumes is primarily stored in the protein bodies of the endosperm.
- Soybeans: Raw soybeans are a notable source of phytase. Fermented soybean products, such as natto and miso, contain high levels of active phytase due to the fermentation process.
- Peas and Lentils: Soaking and sprouting these legumes before cooking can activate their phytase enzymes, leading to reduced phytic acid content and improved mineral availability.
- Chickpeas: As with other legumes, soaking chickpeas for an extended period, such as overnight, dramatically increases phytase activity.
Grains
Whole grains are rich in phytic acid, which is concentrated in the bran and germ. However, they also contain natural phytase enzymes that can be activated through specific preparation methods.
- Rye: This grain is particularly high in native phytase and is often used in sourdough bread to improve mineral absorption from the final product.
- Whole Wheat: The bran of whole wheat is a significant source of both phytic acid and phytase. Lactic acid fermentation, as in sourdough, is an effective method for activating the inherent phytase and breaking down phytic acid.
- Barley and Oats: Soaking and sprouting are effective for these grains. The germination process triggers a strong increase in phytase activity, which breaks down the stored phytates.
Nuts and Seeds
While many nuts and seeds are rich in phytic acid, some contain notable levels of phytase, especially when raw.
- Almonds and Walnuts: Soaking these nuts is a traditional practice aimed at reducing phytic acid, though research suggests its effects on phytate reduction can be minimal compared to grains. However, this process can still activate some enzymes.
- Sesame and Flax Seeds: Soaking and grinding these seeds can expose the phytase to phytic acid, initiating the breakdown process.
Fruits and Vegetables
Certain fruits and vegetables contain phytase, though often in lower concentrations than grains and legumes.
- Avocado: Research has shown that avocado contains detectable phytase activity.
- Scallion Leaves: A study noted that scallion leaves had high phytase activity, demonstrating that some vegetables can be a dietary source.
Table: Comparison of Foods High in Phytase vs. Processing Effectiveness
| Food Type | Raw Phytase Activity | Effective Processing Method(s) | Mineral Bioavailability Impact |
|---|---|---|---|
| Legumes (Soybeans, Peas) | Moderate to high | Soaking, Sprouting, Fermentation | Substantial increase |
| Whole Grains (Rye, Wheat) | Moderate to high (bran/germ) | Soaking, Fermentation (especially sourdough) | Significant increase |
| Nuts (Almonds, Walnuts) | Low to moderate | Soaking (limited effect), Grinding | Modest increase (more debated) |
| Seeds (Sesame, Flax) | Moderate | Soaking, Grinding | Moderate increase |
| Mushrooms | Undocumented for most types | N/A | Unknown/Low |
| Fruits (Avocado) | Low to moderate | N/A (eat raw) | Likely minor increase |
Microbial Sources and Supplements
For decades, commercial microbial phytase has been used in animal feed to improve nutrient absorption and reduce environmental phosphorus pollution from waste. This has paved the way for human applications, especially in food processing.
- Fermented Foods: Products made with yeast or bacteria, such as sourdough bread and certain soy products, use microbial phytase to break down phytic acid.
- Phytase Supplements: Available as dietary supplements, these offer a concentrated dose of the enzyme, often derived from fungi like Aspergillus niger. Studies suggest they can significantly increase iron and zinc absorption, though long-term effects still require more research.
How to Maximize Phytase Intake and Activation
To get the most out of phytase-containing foods, combining them with certain preparation methods is key. Simple practices can dramatically improve the enzyme's activity and, by extension, your body's ability to absorb vital minerals.
Soaking: A simple overnight soak for legumes and some grains activates endogenous phytase. Soaking also helps remove other antinutrients. Ensure you discard the soaking water as it will contain leached phytates.
Sprouting/Germination: This process activates the seed's own enzymes, including phytase, to make stored nutrients available for growth. Sprouting seeds and legumes can increase phytase activity dramatically and reduce phytic acid content by a significant margin.
Fermentation: The acidic environment created during fermentation is ideal for phytase to function. Sourdough fermentation is a prime example of this, where microbial and grain phytase work to break down phytic acid in the dough.
Conclusion
Activating the phytase enzyme in plant-based foods is a highly effective, natural strategy for improving mineral bioavailability in your diet. By incorporating simple, traditional food preparation techniques like soaking, sprouting, and fermentation, you can unlock the nutritional potential of staple foods like grains and legumes. While the phytase content and activation vary between food types, a varied diet rich in these prepared plant foods can help ensure adequate mineral absorption. The benefits extend beyond nutrition, as these methods also improve the texture and digestibility of your meals. Adopting these practices is a practical step towards enhancing overall digestive and nutritional health, especially for those who consume a high-phytate diet.
