Is Caffeinated Tea Really Dehydrating?

Phytonutrients exclusive to the tea plant appear so powerful that they can reverse disease even when just applied to the skin. Now officially incorporated into the Centers for Disease Control STD Treatment Guidelines, the topical application of green tea extracts on external genital warts results in an astounding 100% clearance in more than half the patients tested (see my 2-min. video Treating Genital Warts With Green Tea).

Green tea may even stop skin cancer. In Treating Gorlin Syndrome With Green Tea, I describe a remarkable case report of a woman with basal cell nevus syndrome, a rare genetic condition in which one’s body becomes covered in skin cancers. Her cancer was apparently reversed with topical green tea body wraps. This builds on research into the dietary reversal of other cancers (see Cancer Reversal Through Diet?).

These examples are a testament to the Power of Plants. It’s in line with research on cinnamon (The Safer Cinnamon), saffron (Saffron for the Treatment of Alzheimer’s), watermelon (Watermelon as Treatment for Erectile Dysfunction), flaxseeds (Just the Flax, Ma’am), and Indian gooseberries (Amla Versus Diabetes). Since there are few or no downsides to plant food remedies–if anything, lots of positive side effects!–I have rarely hesitated to prescribe such natural products in my own medical practice.

Which type of tea is best to consume internally? The same leaves of the same plant are used to make white, green, oolong, and black tea. The primary difference is how they are processed; white being the least processed and black being the most. In Green Tea vs. White, I showed that green tea has the most antioxidant power–unless you added lemon, in which case white tea pulls ahead. New research has taken this a step further and tested their respective abilities to prevent DNA damage. In my 2-min. video Antimutagenic Activity of Green vs. White Tea, green is pitted against white in a head-to-head test against a potent carcinogen found in grilled chicken. White won, and the longer it was brewed, the more protective it became.

The longer-the-better brewing time didn’t surprise me, but this did: Cold Steeping Green Tea. Another way to maximize the phytonutrient absorption from tea is to eat it; see Is Matcha Good for You? and A Better Breakfast. One can overdo it though (see Overdosing on Tea). Other ways to protect one’s DNA include eating broccoliavoiding bacon, not overdoing stevia, as well as eating a plant-based diet in general (see Repairing DNA Damage and Research Into Reversing Aging).

Isn’t caffeinated tea dehydrating though? Comparing up to 6 cups of caffeinated black tea a day to water, researchers studied the common assertion that tea acts as a diuretic and is not as hydrating as plain water. Find out the results in my short video Is Caffeinated Tea Dehydrating? The nutrition without calories concept in the video refers, not surprisingly, to my video Nutrition Without Calories.

For more on caffeine myths, see What About the Caffeine? For the antioxidant comparison of black tea to other teas, see Better Than Green Tea? The “less healthy beverages” line is likely an allusion to soda, about which I have a dozen videos including Food Industry “Funding Effect”Mercury in Corn Syrup?Diet & Hyperactivity, and Is Sodium Benzoate Harmful?

-Michael Greger, M.D.

Image credit: ienjoysushi / flickr


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

23 responses to “Is Caffeinated Tea Really Dehydrating?

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  1. Can atrial fib. patients safely drink caffeinated teas in moderation? I love tea but have avoided caffeinated teas in recent years since my diagnosis. Do decaf teas also provide the same health benefits?


  2. Dr. Greger, does drinking nut/seed-based milks, like hemp or almond, interfere with absorption of antioxidants in tea (particularly green tea)?  I saw the study on this with soy and cow’s milk that said they did interfere and wondering whether the same is true of nut milks.  Thanks!


        1. What your stating is not factually based with evidence that millions of people who drink mate do not get cancer. We should strive to avoid as many carcinogens as possible.


          1.  The evidence is people are alive in heavy drinking countries and not getting more cancer due to mate. Where is your evidence that mate causes cancer?


                1.  You need a study to show that these potent carcinogens specifically from yerba mate cause cancer? This is what carcinogens tend to do. You can find anything on the internet. I am more interested in the science.



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