Tea doesn't deplete the iron already in your body, but it does hinder absorption of nonheme iron. The amount of iron you absorb from foods depends on whether the iron is in ferrous or ferric form and the presence or absence of various compounds, including those found in tea, you consume along with your dietary iron. The most significant factor affecting iron absorption is the amount or iron already in your body. If you have low iron levels, your body absorbs iron more efficiently, but if your iron levels are high, your body will absorb less iron to prevent iron overload.
Heme vs. Nonheme Iron
Animal- and plant-based foods contain different types of iron. Heme iron is a ferrous form of iron having a +2 charge. It occurs in hemoglobin, a protein involved in transportation of oxygen by your blood. Heme iron is only present in foods that once contained blood, namely meat and fish. Nonheme, a ferrous type of iron, carrying a +3 charge, is in plant-based foods and is used in enriching foods. Heme iron is the better absorbed of the two types.
Absorption of Heme Iron
You absorb heme iron, the type found in animal and fish flesh, better than nonheme iron. Depending on how much iron you have in your body, you can absorb from 15 to 35 percent of the heme iron from foods. Other foods do not strongly affect the absorption of heme iron. If you drink a glass of iced tea along with a steak, for example, that will not significantly affect the amount of iron you absorb from the steak.
Hindering Absorption of Nonheme Iron
You absorb 2 to 20 percent of nonheme iron you consume. How much nonheme iron you absorb from foods or supplements depends on what other foods or supplements you are consuming at the same time. Tannins, found in tea, are among the compounds that can decrease absorption of nonheme iron. Other food components or supplements that can decrease nonheme iron absorption include calcium; phosphates in sodas; polyphenols in coffee, tea, red wine and purple grape juice; phytates in legumes and whole grains; and oxalic acid in spinach and chocolate.
Increasing Absorption of Nonheme Iron
You can increase absorption of nonheme iron by consuming it along with meat protein or vitamin C. Many compounds found in fruit also increase iron absorption.
Iron Consumption Strategies
If you want to increase iron absorption, try consuming your iron sources along with meat, orange juice or other vitamin C-rich foods, but avoid drinking tea, soda, coffee or other iron-absorption inhibitors with your main sources of iron. Consult a health care provider or registered dietitian to assess whether your iron intake is appropriate for your age, sex and condition.
References
- Springleaf Iced Tea: Tea and Iron Absorption
- "British Journal of Nutrition"; Inhibition of Non-Haem Iron Absorption in Man by Polyphenolic-Containing Beverages; Richard F. Hurrell, et al.;1999
- Massachusetts Institute of Technology Sports Medicine; Optimizing Your Diet: Best Foods for Specific Minerals; K. Davis
- Office of Dietary Supplements: Iron
- Harvard University Health Services: Iron Nutrition
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