Skip to content
Ntro

Which nutrients do phytates block?

•
4 min read

Phytates, also known as phytic acid, are natural compounds found in plant seeds that can interfere with the absorption of essential minerals. Specifically, they have a strong binding affinity for minerals such as iron, zinc, and calcium, creating insoluble complexes in the digestive tract that the body cannot easily absorb. For most people on a balanced diet, this effect is minimal, but for those with mineral deficiencies or diets heavily reliant on high-phytate foods, it can be a significant concern.

Quick Summary

Phytates, or phytic acid, block the absorption of key minerals like iron, zinc, calcium, and magnesium by binding to them in the digestive tract. High intake of phytates, common in plant-based diets, can reduce mineral bioavailability, though various preparation methods help mitigate this effect.

Key Points

  • Iron Absorption: Phytates significantly inhibit the absorption of non-heme iron from plant-based foods.

  • Zinc Bioavailability: The chelation effect of phytates reduces the bioavailability of zinc, especially in diets rich in grains and legumes.

  • Calcium Binding: Phytates bind with calcium ions, forming insoluble compounds that hinder its absorption, though effects can be mitigated.

  • Preparation Methods: Soaking, sprouting, and fermenting foods are effective ways to reduce phytate content and improve mineral absorption.

  • Balanced Diet: For most people with a varied diet, phytates are not a major concern; however, individuals with mineral deficiencies or on strict plant-based diets should be mindful.

  • Beneficial Properties: Despite their antinutrient properties, phytates also offer health benefits, including antioxidant effects and potential protection against certain diseases.

In This Article

Understanding Phytates: Nature's Mineral Binders

Phytates, chemically known as myo-inositol hexakisphosphate (IP6), are the primary storage form of phosphorus in many plant tissues, particularly in the seeds, grains, legumes, and nuts. In the wild, this compound serves several critical functions for the plant, including protecting it from predators and providing the necessary phosphorus for germination. However, when consumed by humans, phytates act as an "antinutrient" because our digestive systems lack the enzyme phytase, which is necessary to break down the compound and release the bound minerals. This chelation process is most effective at the slightly acidic to neutral pH levels found in the small intestine, leading to reduced mineral absorption.

The Key Minerals Blocked by Phytates

Phytates are poly-anionic molecules, meaning they carry multiple negative charges that attract and bind to positively charged mineral ions (cations). This binding effectively renders the minerals unavailable for absorption through the intestinal wall, leading to their excretion. The minerals most affected by this process include:

  • Iron: Phytates have a potent inhibitory effect on the absorption of non-heme iron, the type found in plant-based foods. This is a particular concern for vegetarians and vegans, or populations where diets are predominantly plant-based. Studies have shown that consuming just 5–10 mg of phytic acid can reduce iron absorption by up to 50%.
  • Zinc: Zinc absorption is also significantly hindered by the presence of phytates, especially when consumed in high amounts. Low zinc bioavailability is a major concern in developing countries where diets rely heavily on whole grains and legumes.
  • Calcium: Phytates bind to calcium, forming insoluble salts that cannot be absorbed. While less of a concern for meat-eaters, those on a high-phytate, low-calcium diet can be at risk, potentially leading to long-term issues like bone loss.
  • Magnesium and Manganese: The absorption of magnesium and manganese can also be negatively impacted by phytates, although the effect is often considered less severe than with iron and zinc.

Practical Strategies for Reducing Phytates

While the chelating effect of phytates is a reality, it's important to remember that many phytate-rich foods are highly nutritious. Rather than avoiding them, several traditional and modern food preparation methods can dramatically reduce their phytic acid content and enhance mineral absorption.

  • Soaking: Soaking legumes, nuts, and grains in water overnight activates the plant's own phytase enzymes, which begin to break down the phytic acid. This is a common practice used to prepare foods like beans before cooking. For example, soaking chickpeas for 12 hours can reduce phytic acid by over 50%.
  • Sprouting: The process of germination, or sprouting, further activates phytase, causing a significant breakdown of phytic acid. Sprouting grains and legumes before cooking is an effective way to lower phytate levels.
  • Fermentation: Lactic acid fermentation, as used in sourdough bread, is particularly effective at degrading phytates. The acidic environment and the activity of microorganisms help break down the compound, improving mineral bioavailability.
  • Cooking: While not as effective as soaking or fermenting, cooking can also reduce phytate content. Prolonged cooking, especially boiling, can help lower the concentration of phytic acid.
  • Combining with Vitamin C: Consuming phytate-containing foods with a source of vitamin C can significantly improve non-heme iron absorption, effectively counteracting the inhibitory effect.

Benefits vs. Drawbacks: A Comparative Look

Feature Antinutrient Effect Beneficial Effects
Mineral Absorption Inhibits absorption of crucial minerals like iron, zinc, calcium, and magnesium, potentially leading to deficiencies. -
Antioxidant Properties - Acts as a potent antioxidant, helping to neutralize harmful free radicals in the body.
Cancer Protection - May help protect against certain types of cancer, particularly colon cancer.
Cardiovascular Health - May prevent the formation of calcium deposits, which can protect against cardiovascular disease.
Bone Health Can potentially reduce calcium absorption over the long term if not managed, increasing osteoporosis risk in vulnerable groups. Can prevent bone loss, with higher phytate intake correlated with stronger bones in some studies.
Blood Sugar Control - Can help regulate blood sugar by slowing carbohydrate digestion, which is beneficial for managing insulin resistance.

Conclusion

Phytates, or phytic acid, are naturally occurring compounds in many healthy plant-based foods that can impede the absorption of essential minerals such as iron, zinc, calcium, and magnesium. For most individuals consuming a varied and balanced diet, the impact on mineral status is minimal. However, for those with nutrient deficiencies, vegetarians, or those on diets high in phytate-rich foods, it is wise to employ preparation methods like soaking, sprouting, and fermenting to reduce phytate levels. Moreover, consuming foods rich in vitamin C alongside high-phytate meals can enhance iron absorption. The key takeaway is that phytates are not inherently "bad" and offer significant health benefits, but being mindful of their presence and how food is prepared can help optimize nutrient intake.

References

Note: The content presented is for informational purposes only and should not be considered medical advice. Always consult with a healthcare professional before making significant changes to your diet, especially if you have a known mineral deficiency.

Frequently Asked Questions

Phytic acid, or phytate, is a compound found in plant seeds, grains, and legumes. It serves as the main storage form of phosphorus for the plant but acts as an "antinutrient" in human digestion because it binds to minerals like iron, zinc, and calcium, reducing their absorption.

Phytates most notably block the absorption of iron (specifically non-heme iron from plants), zinc, and calcium. The absorption of magnesium and manganese can also be affected, though often to a lesser extent.

For most people who consume a well-balanced diet with a variety of foods, the impact of phytates on mineral absorption is minimal. It is more of a concern for those with pre-existing mineral deficiencies, vegetarians, vegans, or populations relying heavily on high-phytate staples.

You can reduce phytate levels by soaking grains, nuts, and legumes overnight before cooking. Other effective methods include sprouting (germination) and fermentation, as seen in sourdough bread.

No, phytates do not block all mineral absorption. Their inhibitory effect is limited to the meal in which they are consumed and does not affect absorption from subsequent meals or snacks. The overall impact depends on the total amount of phytate consumed and the balance of your diet.

Cooking can reduce phytic acid content to some degree, but it is not the most effective method on its own. Combining cooking with soaking or other preparation techniques is more effective at significantly lowering phytate levels.

Phytates also have beneficial properties. They act as antioxidants and have been linked to protective effects against certain cancers, cardiovascular calcification, and bone loss, showing that they are not purely negative compounds.

Related Topics:

#magnesium #zinc #Iron deficiency #calcium #phytic acid #mineral absorption #Nutrient Bioavailability #antinutrients

Medical Disclaimer

This content is for informational purposes only and should not replace professional medical advice.