What Is Phytic Acid and Why Should You Reduce It?
Phytic acid is the main way phosphorus is stored within plant seeds, especially in the outer bran layers of whole grains like oats. When consumed, this compound can bind to minerals, including iron, zinc, magnesium, and calcium, in the digestive tract, forming insoluble phytates. Since the human digestive system lacks sufficient phytase—the enzyme needed to break down phytic acid—these minerals can pass through the body unabsorbed, potentially leading to mineral deficiencies over time, particularly for those on a high-grain, vegetarian, or vegan diet.
Removing or significantly reducing phytic acid is often referred to as 'dephytinization.' This process can make the essential vitamins and minerals naturally present in oats more bioavailable and improve the nutritional value of your meal.
How to Reduce Phytic Acid in Oats
While oats contain less inherent phytase compared to other grains like rye, several effective methods exist to tackle phytic acid. Combining these approaches is often the most potent strategy for maximum reduction.
Method 1: Soaking with an Acidic Medium
Soaking is the simplest and most common method for reducing phytic acid. The process works best with warmth and an acidic environment, which helps activate any remaining phytase and encourages beneficial bacteria to break down phytates.
Steps for Soaking:
- Use a ratio of 1 part rolled oats to 1.5 parts warm, filtered water. Using warm, but not boiling, water is optimal, as the phytase enzyme is most active at temperatures between 45–65°C.
- Add an acidic ingredient. This can be 1-2 tablespoons of lemon juice, apple cider vinegar, or live whey per cup of oats.
- Stir the mixture thoroughly in a glass or ceramic bowl.
- Cover the bowl and let it sit at room temperature for at least 8 to 12 hours, or overnight.
- In the morning, the oats can be rinsed and cooked, or used directly in recipes for overnight oats. Rinsing is optional but can help remove some of the acidulated liquid.
Method 2: Fermentation with a High-Phytase Grain
Because oats are naturally low in the phytase enzyme, fermenting them with a starter or flour from a high-phytase grain (like freshly ground rye or buckwheat) is a highly effective technique. The lactic acid produced during fermentation also helps degrade phytates.
Steps for Fermentation:
- Combine your rolled oats with a small amount of freshly ground rye or buckwheat flour.
- Add a live, acidic starter culture such as a rye sourdough starter or a probiotic liquid like kefir.
- Mix with warm water to a porridge-like consistency.
- Allow the mixture to ferment for 12 to 24 hours at room temperature.
- After fermenting, cook the oats as desired. Studies show fermentation can achieve a significant reduction in phytic acid.
Method 3: Sprouting the Oat Groats
Sprouting, or germination, activates the phytase enzyme naturally present in the grain to break down phytic acid. This method is suitable only for intact oat groats, as rolled or steel-cut oats are too processed to sprout. Sprouting significantly reduces phytic acid, sometimes by up to 98%.
Steps for Sprouting:
- Thoroughly rinse whole oat groats and soak them in filtered water for 8-12 hours.
- Drain and rinse the groats again.
- Place the groats in a jar covered with a breathable lid (like cheesecloth) and store in a warm, dark place.
- Rinse and drain the groats every 8-12 hours to prevent mold growth.
- Small sprouts will appear within 1-3 days. Once sprouted, they can be cooked or dehydrated for later use.
Comparison of Phytic Acid Reduction Methods
| Method | Effectiveness | Best For | Pros | Cons |
|---|---|---|---|---|
| Soaking | Moderate | Rolled, steel-cut oats, overnight oats | Simple, requires minimal preparation time | Requires an acidic medium, less effective than sprouting or fermenting |
| Fermentation | High | Porridge, baked goods, sourdough | Highly effective, enhances flavor and texture, improves digestibility | Requires a live starter and high-phytase grain (like rye), takes longer |
| Sprouting | Very High | Whole oat groats, dehydrated snacks | Most effective method for phytic acid reduction | Only works for intact oat groats, more time and labor-intensive |
| Cooking | Low to Moderate | Any oat type | Requires no pre-preparation, convenient | Significantly less effective than other methods, especially without pre-soaking |
Combining Techniques for Better Results
For those seeking the highest level of phytic acid reduction, combining methods is the most powerful strategy. For instance, you could use fermented sprouted oat groats for maximum effect. For a simpler, everyday approach, combine soaking with an acidic medium followed by cooking. The heat from cooking, after the phytates have been broken down, helps to further solidify your efforts. To improve iron absorption specifically, consider adding foods rich in vitamin C, like berries, to your cooked oatmeal, as it significantly enhances the bioavailability of non-heme iron.
Conclusion
Preparing oats to remove phytic acid is a worthwhile effort for anyone looking to maximize the mineral absorption from their grains. While soaking is an accessible and effective first step, advanced techniques like fermenting with a high-phytase grain or sprouting oat groats offer the most significant reductions. By incorporating these traditional food preparation practices into your cooking routine, you can turn a simple bowl of oatmeal into an even more nutrient-dense and digestible meal. Understanding these methods empowers you to control your nutrition and get the most out of one of the world's healthiest grains.
Resources for Further Information
For more in-depth research on phytic acid and grain preparation, see the National Institutes of Health article on the Reduction of phytic acid and enhancement of bioavailable micronutrients in food grains: https://pmc.ncbi.nlm.nih.gov/articles/PMC4325021/.
