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Green Tea

Posted: Thu Jul 26, 2012 10:10 am
by mickey
Hi, Tom,

Does green tea contain tannin? I am interested as I have an iron deficiency.

Re: Green Tea

Posted: Fri Jul 27, 2012 9:05 am
by Tom Hagerty
Yes, tea contains tannins, darker teas containing more than lighter teas. Tea, though, does not contain tannic acid, which is used to make leather. But what you want to know is if these tannins in tea have any effect in preventing or slowing down the absorption of dietary iron. This is a complex issue that I will try to make simple.

The iron you get in food is in two forms - heme and non-heme. Heme iron is in the meat you eat; non-heme iron is the iron you get from plant sources - vegetables, whole grains, leafy greens, and the list goes on. The heme iron you get from meat is unaffected by the tannins in tea. But the non-heme iron you get from plant sources is definitely affected by these tannins. The iron that you absorb from plant sources is poorly absorbed to begin with, so adding tannins to the mix makes this iron even less bioavailable.

If you are borderline anemic or have a low serum ferritin level, I would be careful about drinking gallons of tea, especially if you are a vegetarian or one who eats little meat. I prefer drinking tea at least an hour before or after meals. This way the tannins have little effect on iron absorption.

Re: Green Tea

Posted: Sat Jul 28, 2012 8:10 am
by mickey
How can I easily monitor my iron levels, to ensure they are sufficient ?

Re: Green Tea

Posted: Mon Jul 30, 2012 7:25 am
by Tom Hagerty
By far the best test for finding out if have sufficient iron levels is the serum ferritin test. You have to ask a doctor specifically for this test. The test measures the carrier molecule for iron. This is a protein that stores the iron. If you have low ferritin levels you iron levels are almost certainly low. The best range of serum ferritin is between 20 and 80 ng/ml (nanograms per mililiter). Between 40 and 80 is even better. If you are below 20 you are iron deficient; if you are above 80 you have too much iron. Too much iron is not good either. That's why it's not a good idea to get your iron from supplements - the chance of iron overload. Red meat is the best source of bioavailable iron. The iron you get from plant sources (spinach, broccoli) is assimilated poorly.