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Polyphenol-Rich Foods – Can They Cause an Iron Deficiency?

Dr. Kristie Leong

Polyphenols are natural compounds found in plants that have antioxidant benefits. Many experts recommend eating a polyphenol-rich diet to help reduce the risk of conditions such as heart disease and cancer. Could there be drawbacks to adding more polyphenol antioxidants to your diet? According to a new study, polyphenol-rich foods may reduce the absorption of iron, and, possibly, lead to an iron deficiency.

Polyphenol-Rich Foods: What Are They?

Ever wonder what foods contain polyphenols? The best sources of polyphenol antioxidants are dark chocolate, tea, berries, walnuts, coffee, wine, olive oil, fruits, and vegetables - all foods that are widely considered to be healthy.

Can the Polyphenols in Foods Cause an Iron Deficiency?

Recently, researchers discovered that the polyphenol antioxidants in green tea and grape seed extract block absorption of iron by the intestines. They do this by binding to iron and forming a complex that can't be transported into intestinal cells. Because they can't be absorbed, these iron-containing complexes are excreted into the feces.

The majority of men and post-menopausal women aren't deficient in iron, so this loss of iron would be less of a problem for them. For some older women and men, lowering iron stores may actually be beneficial to overall health. On the other hand, some pre-menopausal women already have low iron stores due to regular menstrual bleeding and eating too many polyphenol-rich foods could further lower them.

Do Polyphenol-Rich Foods Reduce Absorption of Other Nutrients?

If polyphenol antioxidants can cause an iron deficiency by blocking absorption of iron, they may also interfere with that absorption of other minerals such as calcium, zinc, and magnesium that have a similar electrical charge. This hasn't been well studied, so it's too early to say whether it holds true.

Can Polyphenol-Antioxidants Cause an Iron Deficiency: The Bottom Line?

Polyphenol antioxidants have some promising health benefits, but they may also reduce iron absorption. Is there a way to still get the benefits of polyphenols without lowering iron levels?

Try eating polyphenol-rich foods at a meal where you're not eating foods rich in iron - and don't drink tea, wine or coffee when you eat a meal. If your doctor prescribed an iron supplement, take it on an empty stomach - or with only a small amount of food that's not high in fiber or polyphenols. If you’re concerned about your iron levels, avoid taking supplements that contain very large quantities of polyphenols - and get your iron levels checked every six months.

The bottom line? Polyphenols are beneficial, but consume them in moderation.


References:
Medical News Today. “Iron Absorption Inhibited By Polyphenol Antioxidants”

Health Disclaimer. Copyright ©2010. Dr. Kristie Leong is a family practice physician and medical writer. Published with permission.