You Ask, I Answer: Tea, Caffeine, & Hydration

I know that caffeine is a diuretic. I drink black tea in the morning then switch to herbal in the afternoon. I have convinced myself that since the herbal tea doesn't have caffeine that it is a good source of water and hydration. Am I thinking clearly in this regard?

Regarding the black tea - I make a large pot of tea with a single tea bag - pretty much 3 or 4 cups with just one bag. Does this still put me in water deficit or do I get partial credit for the water consumption?

Always wondered about this - what is the equilibrium point for water and caffeine when it comes to tea?

And, any thoughts about green tea and water consumption?

-- Quinn Andrus
American Embassy in Doha, Qatar

Many people think nutrition deals exclusively with food, but liquid intake also plays a significant role.

After all, humans can survive for up to six weeks without food, but only a week without water.

Like solid food, liquids also fall prey to myths.

A popular one? That tea is a diuretic.

The Institute of Medicine released revised hydration guidelines in April of 2004 which concluded there is no evidence that moderate intake of caffeine results in "body water deficits".

This is not to say caffeine in and of itself is not a diuretic – it is, in the sense that it increases urine production, especially when consumed in high doses.

Keep in mind, though, that the same thing can be said about water. You will urinate at a higher volume on the days you drink ten, rather than five, glasses of water.

Unlike water, though, caffeine can relax the lower esophageal sphincter and cause acid reflux.

But, let's go back to the issue of hydration.

A 2000 study published in the Journal of American College of Nutrition concluded that there is no evidence supporting the commonly held belief that caffeine-containing fluids result in dehydration.

Dehydration has to do with a very simple equation -- fluid intake minus fluid loss. If your equation results in a negative, you are dehydrated. Positive? Then you're fine.

If you feel thirsty and have a cup of tea, you will not be dehydrating yourself further.

It has been determined that in order for tea to have a significant diuretic effect and increase heart rate, one must consume approximately 300 milligrams in one sitting (that is equivalent to six cups of tea).

Additionally, it is also worth noting that, over time, regular tea drinkers develop a tolerance to caffeine.

Remember, too, that hydration recommendations do not only apply to liquids – the foods we eat also contain water.

In conclusion, healthy individuals drinking two or three cups (using three bags) of tea a day -- whether black, green, or white -- do not have to worry about dehydration.