What foods drain iron?

January 7, 2026 •

4 min read

On average, the body only absorbs about 10% of the iron we consume, and certain foods can decrease this amount further by inhibiting the absorption process. Understanding what foods drain iron is crucial for maintaining healthy iron levels, especially for those at risk of deficiency, such as women and children. This can impact overall energy levels and well-being.

Quick Summary

This article explores the dietary compounds that significantly inhibit iron absorption, such as tannins, phytates, oxalates, and calcium. It details which foods contain these inhibitors and offers practical strategies to maximize your body's iron uptake.

Key Points

Tannins and Polyphenols Block Absorption: Compounds in tea, coffee, and wine inhibit the absorption of iron, particularly the non-heme iron found in plants.
Phytates in Grains Reduce Bioavailability: Phytic acid in whole grains, legumes, and nuts can bind to iron, but soaking or sprouting can reduce its impact.
Calcium Inhibits Both Iron Types: High intake of calcium from dairy or supplements can interfere with both heme and non-heme iron absorption, so separate their consumption from iron-rich meals.
Oxalates in Greens Limit Absorption: Found in spinach and other greens, oxalates can bind to iron, but cooking can help mitigate this effect.
Eggs and Soy Also Affect Absorption: Eggs contain phosvitin, while soy proteins also inhibit iron uptake, especially from plant sources.
Vitamin C is a Powerful Enhancer: Pairing iron-rich foods with sources of Vitamin C can significantly increase non-heme iron absorption, helping to counteract inhibitors.
Timing is Everything: Strategically spacing out meals and beverages can prevent key inhibitors from affecting your iron intake, improving overall nutrient absorption.

Iron is an essential mineral vital for producing hemoglobin, the protein in red blood cells that transports oxygen throughout the body. When dietary iron intake is high but overall absorption is low, it can lead to health issues. The key to maximizing iron intake is not just what you eat, but what you eat with it. Not all iron is created equal; there are two main types: heme iron from animal products, which is more readily absorbed, and non-heme iron from plant sources, which is more vulnerable to inhibitors.

Tannins and Polyphenols

These compounds, found in various plant-based items, can hinder non-heme iron absorption by binding to it in the digestive tract. Consuming items high in tannins with a meal can significantly reduce iron uptake.

Tea and Coffee

Tea (black, green, herbal) and coffee are notable sources of tannins and phenolic compounds that strongly inhibit iron absorption. It is recommended to consume these beverages between meals, ideally at least an hour apart, to minimize their effect.

Other Sources

Other sources of these inhibitory compounds include cocoa, dark chocolate, red wine, and certain fruits like berries, as well as some herbs and spices.

Phytates (Phytic Acid)

Phytates are found in plant seeds, grains, and legumes and can bind to minerals like iron, zinc, and calcium, preventing absorption. Even small amounts of phytates can negatively impact non-heme iron bioavailability.

Foods high in phytates: Whole grains, legumes (like lentils and chickpeas), nuts, and seeds are significant sources.
Reducing phytates: Preparation methods such as soaking, sprouting, or fermenting grains and legumes can lower their phytic acid content and enhance iron absorption.

Calcium

Calcium is essential for bone health but uniquely inhibits the absorption of both heme and non-heme iron. This is particularly true when large amounts of calcium are consumed with iron, especially from supplements.

High-calcium foods: Dairy products (milk, cheese, yogurt) and calcium-fortified cereals are examples.
Best practice: To reduce calcium's impact, consume high-calcium foods or supplements at different times than your main iron-rich meals.

Oxalates (Oxalic Acid)

Oxalates are present in certain plant foods and can bind with non-heme iron and calcium, forming compounds that are poorly absorbed.

Foods high in oxalates: Spinach, kale, beets, wheat bran, and chocolate contain significant levels.
Preparation methods: Cooking vegetables can help decrease their oxalate content and improve iron absorption.

Other Inhibitors

Beyond the main culprits, other foods can also affect iron absorption.

Eggs: The protein phosvitin in egg yolks can bind to iron, reducing its absorption.
Soy Proteins: Proteins in soy products can also interfere with non-heme iron absorption.
Dietary Fiber: High amounts of unprocessed fiber, especially from bran, can bind to iron and other minerals.

Boosting Iron Absorption: A Comparison


Inhibitor Type	Primary Food Sources	Iron Type Affected	Management Strategy
Tannins & Polyphenols	Coffee, Tea, Cocoa, Wine	Non-Heme	Consume between meals, not with them.
Phytates	Whole Grains, Legumes, Nuts	Non-Heme	Soak, sprout, or ferment grains and legumes.
Calcium	Dairy Products, Fortified Cereals	Heme & Non-Heme	Separate consumption from iron-rich meals.
Oxalates	Spinach, Kale, Beets, Chocolate	Non-Heme	Cooking can reduce oxalate levels.
Soy Proteins	Soybeans, Tofu	Non-Heme	Can be mitigated by combining with enhancers like Vitamin C.
Eggs (Phosvitin)	Egg Yolk	Non-Heme	Consume eggs separately from iron-focused meals.

Conclusion

While various foods contain compounds that can inhibit iron absorption, understanding these interactions allows for strategic dietary choices to manage their impact. Non-heme iron from plants is more susceptible to inhibitors than heme iron from animal sources. Pairing non-heme iron with vitamin C-rich foods, and timing the consumption of inhibitors like coffee, tea, and calcium, are effective strategies. Soaking or sprouting grains and legumes can also be beneficial. For most people with a balanced diet, these inhibitors don't cause deficiency, but those at risk can significantly improve absorption by following these tips.

For a deeper understanding of mineral absorption biochemistry, authoritative sources are available.

Tips for Better Iron Absorption

Boost with Vitamin C: Combining non-heme iron sources with Vitamin C-rich foods enhances absorption.
Strategize Beverages: Drink coffee, tea, or red wine between meals rather than with them.
Separate Calcium and Iron: Avoid consuming high-calcium foods or supplements simultaneously with iron-rich meals.
Prepare Grains and Legumes Properly: Soaking, sprouting, or fermenting can reduce phytate content and improve absorption.
Cook in Cast Iron: Using a cast-iron skillet can increase the iron content of food.
Consider Heme Iron Sources: Including animal sources of iron can boost overall intake due to better absorption.

Maximize Your Iron Intake

Consume Vitamin C: Pairing non-heme iron sources with vitamin C-rich foods like citrus fruits or bell peppers significantly enhances absorption.
Strategize Beverages: Avoid drinking coffee and tea with iron-rich meals due to tannin content, consuming them between meals instead.
Separate Calcium: Do not consume high-calcium dairy products or supplements at the same time as an iron-dense meal, opting to have them with a snack.
Prepare Grains and Legumes: Soaking and sprouting can reduce phytate levels in these foods, improving iron bioavailability.
Cook with Cast Iron: Using a cast-iron skillet, particularly with acidic foods, can naturally increase food's iron content.

Frequently Asked Questions

If you are iron deficient, you should consume coffee and tea at least one hour before or after your main iron-rich meals. The tannins and polyphenols in these drinks are potent inhibitors of iron absorption.

While spinach contains iron, it is also high in oxalates, which significantly hinder its absorption. To maximize the iron you do get, eat spinach with a source of vitamin C, and note that cooking can reduce the oxalate content.

You can reduce the phytate content in legumes, nuts, and grains by soaking them overnight, sprouting them, or fermenting them. These processes help to neutralize the phytic acid, improving iron absorption.

No, you don't need to avoid dairy entirely. The key is to avoid consuming high-calcium dairy products or supplements at the same time as your main iron-rich meals. Separating their intake by a few hours can prevent the inhibitory effect.

To maximize iron absorption from beans, a plant-based source of non-heme iron, eat them with a vitamin C-rich food like tomatoes or bell peppers. Soaking and sprouting the beans before cooking also helps.

Yes, eggs contain a protein called phosvitin that binds to iron and can inhibit its absorption. If you have an iron deficiency, it's best to consume eggs away from other iron-rich meals to minimize this effect.

Yes, non-heme iron from plant-based foods is significantly more affected by dietary inhibitors like tannins, phytates, and oxalates. Heme iron from animal sources is much more readily absorbed and less impacted by these compounds.