What are Phytates?
Phytates are the salts of phytic acid, also known as myo-inositol hexakisphosphate (IP6). This molecule is the primary storage form of phosphorus in many plant tissues, particularly the hulls and kernels of seeds, grains, and legumes. In nature, this compound plays a vital role in providing phosphorus and mineral cations to the plant seedling during germination. However, in human digestion, the high density of negatively charged phosphate groups on the phytate molecule gives it a strong affinity to bind with positively charged mineral ions.
When we consume foods high in phytates, these molecules bind to minerals in our gastrointestinal tract, especially in the neutral pH environment of the small intestine where most mineral absorption occurs. This process, called chelation, forms insoluble mineral-phytate complexes that are resistant to human digestion and cannot be absorbed by the body. Because humans lack the enzyme phytase in sufficient quantities to break down phytates, these mineral complexes are simply excreted. The impact of this is most pronounced in populations that rely heavily on unrefined plant-based foods for their staple diet, where a combination of high phytate intake and potentially low mineral intake can lead to mineral deficiencies.
Minerals that Bind with Phytates
- Zinc: Zinc has one of the strongest binding affinities for phytates. The formation of zinc-phytate complexes is a major factor in compromised zinc status, especially in high-phytate diets. The presence of high calcium levels can further exacerbate this binding by creating an even less soluble calcium-zinc-phytate complex.
- Iron: Phytates are a primary inhibitor of non-heme iron absorption from plant-based foods. The inhibitory effect is dose-dependent, meaning even small amounts of phytates can reduce iron absorption. This is particularly relevant for vegetarians and vegans who get most of their iron from plant sources.
- Calcium: Although some binding occurs, the effect of phytates on calcium absorption is most concerning when dietary calcium intake is already low. A high dietary calcium-to-phytate ratio is crucial for preventing negative interactions. However, excessive calcium can worsen the inhibitory effect of phytates on zinc absorption.
- Magnesium: The interaction between phytates and magnesium is less straightforward than with zinc and iron. The binding affinity is lower, and the impact may only be significant when magnesium intake is already marginal.
- Copper: Research has shown that copper can also bind with phytates, particularly at the pH levels found in the small intestine. Some studies, primarily in poultry science, have indicated that copper's high affinity for phytates can interfere with mineral availability.
- Manganese: As with other divalent cations, manganese can be chelated by phytates, reducing its bioavailability.
How to Mitigate Phytate's Effects
Fortunately, several traditional food preparation methods can significantly reduce phytate levels in food, improving the bioavailability of minerals.
- Soaking: Soaking grains, legumes, nuts, and seeds in water for several hours or overnight activates endogenous phytase enzymes that break down phytic acid. Discarding the soaking water further removes some of the dissolved phytates.
- Sprouting or Germination: This process involves germinating seeds or grains, which dramatically increases the activity of natural phytase enzymes, leading to a substantial reduction in phytate content. Sprouting can be performed at home and is a very effective strategy.
- Fermentation: Fermentation, such as in making sourdough bread or traditional fermented foods, employs beneficial bacteria that produce phytase. The acidic environment created during fermentation also helps to activate the grain's native phytase, resulting in significant phytate degradation.
- Cooking: While less effective than soaking or sprouting, cooking, especially with methods like boiling, can degrade some of the phytic acid. Combining cooking with soaking can yield better results.
- Pairing Foods: Consuming foods rich in vitamin C, like citrus fruits or bell peppers, alongside high-phytate meals can help counteract the inhibitory effect on iron absorption. Some proteins and organic acids can also help improve mineral absorption.
Comparison of Diets: High vs. Low Phytate
| Feature | High-Phytate Diet | Low-Phytate / Properly Prepared Diet |
|---|---|---|
| Mineral Bioavailability | Reduced, leading to lower absorption of minerals like zinc, iron, and calcium. | Enhanced, improving the absorption and utilization of essential minerals. |
| Typical Foods | Unrefined whole grains, raw beans, uncooked seeds, and nuts. | Soaked, sprouted, or fermented versions of high-phytate foods. |
| Preparation | Minimal or no preparation methods used to break down phytates, such as simple cooking. | Utilizes soaking, sprouting, and fermentation to activate phytase enzymes. |
| Mineral Status Risk | Higher risk for mineral deficiencies, especially for vegans, vegetarians, and those in developing nations relying on plant-based staples. | Lower risk of mineral deficiency due to improved nutrient access, even with a plant-centric diet. |
| Health Considerations | While not inherently bad and offers antioxidants, chronic high intake in vulnerable groups can impact mineral status. | Optimizes nutritional status by overcoming the inhibitory effects of phytates while still benefiting from other plant compounds. |
Are Phytates Inherently Bad for Your Health?
It is important to remember that labeling phytates as simply 'bad' is an oversimplification. While their ability to bind minerals is a negative aspect from an absorption perspective, phytates also offer potential health benefits. They act as antioxidants, protect against inflammation, and have been studied for their potential anticancer properties. For most people in developed countries who consume a diverse and balanced diet, the presence of phytates is unlikely to cause significant mineral deficiency.
The real issue is not the presence of phytates, but rather the overall dietary context. For individuals with high phytate consumption coupled with marginal mineral intake, such as some vegans, vegetarians, or those on resource-limited diets, the inhibitory effect can be more pronounced. In these cases, employing the preparation techniques mentioned above is a practical and effective strategy to maximize nutritional gains from plant-based foods.
Conclusion: Navigating a High-Phytate World
Understanding which minerals are binding with phytates is a crucial part of optimizing nutrient intake, especially in a modern diet that heavily features whole grains, nuts, and legumes. While the chelation process can inhibit the absorption of key minerals like zinc, iron, and calcium, this does not mean that phytate-rich foods should be avoided. Instead, we should embrace traditional and time-tested preparation methods like soaking, sprouting, and fermentation. By doing so, we can deactivate phytates, unlock the full nutritional potential of plant-based foods, and ensure that our bodies receive the essential minerals needed for optimal health. This balanced approach allows for the benefits of plant-based nutrition while mitigating its drawbacks, promoting a truly healthful and nourishing diet.
