How long does it take to break down phytic acid?

December 29, 2025 •

3 min read

Phytic acid, a compound found in many plant foods, is known for binding to essential minerals like iron, zinc, and calcium, hindering their absorption. While complete elimination is often unnecessary for a balanced diet, proper preparation can significantly reduce its levels and improve nutrient bioavailability. This process varies widely depending on the method and food type.

Quick Summary

Methods like soaking, sprouting, and fermenting can reduce phytic acid, with breakdown times varying based on the specific technique and food. Warm temperatures and acidic mediums can accelerate the process, increasing mineral bioavailability.

Key Points

Soaking: Takes 7-24 hours, often with an acidic medium, to reduce phytic acid in grains and legumes.
Sprouting: Involves germination over 1-10 days, significantly increasing phytase activity to break down phytates.
Fermentation: Highly effective method, with sourdough taking 4-12 hours for significant reduction.
Cooking: Provides moderate reduction, particularly when combined with prior soaking.
Optimal Conditions: Warm temperatures (45-65°C) and a slightly acidic pH (5.0-6.0) boost phytase activity.
Food Type Matters: Natural phytase varies; rye and wheat are high, oats and brown rice are lower.

Understanding Phytic Acid and Phytase

Phytic acid, or phytate, is the primary storage form of phosphorus in many plants, especially grains, legumes, nuts, and seeds. It is considered an 'anti-nutrient' because it can bind to essential dietary minerals such as iron, zinc, calcium, and magnesium, making them less available for absorption by the body. Humans lack sufficient levels of the enzyme phytase in their digestive tracts to effectively break down phytic acid. Breakdown (dephytinization) is primarily achieved through specific food preparation techniques that activate the food's own enzymes or introduce external ones.

Key Factors Influencing Phytic Acid Breakdown

Several factors influence the effectiveness and speed of phytic acid reduction:

Method: Soaking, sprouting, and fermentation have different effects.
Food Type: Natural phytase content varies; rye and wheat are high, oats and brown rice are lower.
Temperature: Phytase is most active in warm conditions (45-65°C / 113-149°F).
pH Level: An acidic medium (pH 5.0-6.0) is ideal for phytase.
Time: Duration of preparation correlates with reduction.

How Long to Break Down Phytic Acid: Method-Specific Timelines

Soaking Grains and Legumes

Soaking involves submerging food in water, often with an acidic medium, to activate natural phytase enzymes.

Soaking Time: Typically 7-24 hours. Longer soaks (up to 36 hours for some legumes) with water changes may be used.
Conditions: Warm water and adding acid (vinegar, lemon juice) increase efficiency. A study on chickpeas showed a 47-55% reduction with a 2-12 hour soak.
Effectiveness: Best for foods with high inherent phytase like rye and wheat, and for beans/legumes.

Sprouting (Germination)

Sprouting activates natural phytase to break down phytic acid and release minerals.

Sprouting Time: Significant reduction occurs within days. Malting millet for 72-96 hours reduced phytic acid by 23.9-45.3%. Significant reduction in cereals can take around 10 days.
Process: Initial soaking (12-24 hours), followed by rinsing and keeping moist until sprouts appear.
Benefits: Reduces phytic acid and can increase nutritional value.

Fermentation

Fermentation, especially lactic acid fermentation, is highly effective. Organic acids create an ideal environment for phytase.

Fermentation Time: Sourdough bread fermented for 4-8 hours at a warm temperature can significantly reduce phytic acid in whole wheat (up to 60%+). Longer fermentation (around 12 hours) can almost eliminate phytates in whole rye bread.
Mechanism: Uses both the food's enzymes and microbial phytases.
Applicability: Excellent for flours (sourdough) and fermented products like tempeh.

Cooking and Pressure Cooking

Cooking alone offers moderate reduction, but it's less effective than other methods. Cooking legumes for an hour can reduce phytic acid up to 80%, especially after soaking. Pressure cooking is very effective, particularly after soaking.

Comparison of Phytic Acid Reduction Methods

Choosing the Right Method for Your Food

For daily cooking of legumes, overnight soaking and cooking are usually sufficient for a balanced diet. Sourdough fermentation is most effective for whole grain flours high in phytates like rye and wheat. Soaking and dehydrating nuts and seeds can be an option for large quantities. The best method depends on the food and dietary needs; those with mineral deficiencies or diets high in phytates may benefit from more aggressive techniques.

For brown rice, which has lower natural phytase, accelerated fermentation can be highly effective (up to 96% reduction). An 8-hour soak with an acidic medium also provides notable reduction before cooking.

Conclusion

Breaking down phytic acid is time and method-dependent. Soaking takes several hours, fermentation 4 to 24 hours, and sprouting multiple days. For most people with varied diets, traditional methods like soaking and cooking are adequate to improve mineral availability. However, individuals with specific concerns might benefit from longer or advanced techniques like fermentation. Proper food preparation helps maximize nutrient absorption from plant foods.

Are Anti-Nutrients Harmful?

Frequently Asked Questions

For grains with high natural phytase like rye and wheat, sourdough fermentation is highly effective. For others, soaking overnight followed by cooking is reliable.

While oats have lower natural phytase, soaking them overnight (at least 12 hours), optionally with an acidic medium, can help reduce phytic acid.

Soaking beans for 12-24 hours, changing water, significantly reduces phytic acid. Combined with thorough cooking, it's very effective.

Fermentation is highly effective and can lead to near-total reduction, but complete elimination isn't always guaranteed or necessary. Significant reduction is the goal.

Cooking alone offers moderate reduction, less effective than other methods. Combining cooking with a preliminary soak significantly increases reduction.

A minimum of 7 hours is recommended for soaking nuts and seeds, sometimes with salt. After soaking, they can be dehydrated.

Yes, plain water activates some phytase, but adding an acidic medium like lemon juice or apple cider vinegar significantly boosts enzyme activity and speeds breakdown.