Does caffeine cause dehydration?

Thinking & research conflicts on whether caffeine causes dehydration.

We discuss the issue, make recommendations & present a chart detailing the amount of caffeine in selected products at bottom of page.

One experiment showed that consuming caffeine did not lead to losing more urine and therefore doesn’t suggest a caffeine dehydration connection.

However, studies like this are examples of research that is not complete enough to draw conclusions. It simply leads to many other questions.

Do dehydration effects take longer than 4 – 6 hours?

What are dehydration effects for habitual coffee drinkers?

Maybe urine output remains stable but losing just a little, unmeasurable amount of water from cells, over time, may lead to chronic cell dehydration that cannot be measured in a short-term study.

Caffeine dehydration is worsened by adding chemicals, sugars, creamers.What’s the connection between tea & dehydration?

What if caffeinated drinks are combined with sweeteners and creamers? Etc.

Other studies do show caffeine dehydration link. They too do not definitively answer the question.

However, what scientists know about the role of caffeine on biological processes strongly suggests that cola, teas & coffee dehydrate, at least mildly.

Moreover, the lack of enough fluids in the body may make caffeine effects stronger.

This is not good as the following list on the effects of caffeine on the body suggests.

The effects of caffeine on the body

Caffeine has several harmful effects on the body. Some of those effects lead to health problems including dehydration. (In particular #s 3, 6 & 7 below may be cause or lead to dehydration.)

1)Caffeine reduces the hormone melatonin, needed for restful, deep sleep

2)Risk factor for low birth weight newborn

3)Decreases memory enzymes

4)Can damage DNA

5)May cause or worsen attention problems

6)May effect overall brain functioning

7)Caffeine stimulates central nervous system

8)Releases fatty acids that go into the blood system

9)Combined with artificial sweeteners, caffeinated drinks may combine bad effects of caffeine with bad effects of chemical sweeteners for a one – two wallop.

10)Constant, high caffeine intake may cause adrenal fatigue leading to chronic fatigue

Dr. Batmanghelidj suggested that cravings for caffeine signal a need for water. The cravings are learned behaviors where drinking is associated with drinking caffeinated drinks instead of water.

Try drinking primarily water with very few other beverages. You should soon notice that you start craving water like you used to crave coffee or cola. This is the craving that we should all feel but gets displaced onto other drinks. You might conclude that caffeine is bad, period. That’s not our conclusion.

Rather, respect the powerful effect that caffeine has on our bodies and use it strategically.

Examples, a few cups of coffee may break an asthma attack in a pinch. Caffeine may increase endurance if consumed in moderation an hour before exercise.

The problem is that if you are a heavy chronic user, are in poor shape & do not drink enough water, caffeine becomes an ever-present toxic rather than a useful supplement.

So drink a cup of Joe, or a few cups of tea high in antioxidants. Just make sure that your other lifestyle choices are healthy.


Caffeine Levels (in milligrams)

Coffee (10 oz.) brewed, drip, 230 mg

Coffee (10 oz.) instant, 130

Coffee (10 oz.) decaf, 5

Tea (10 oz, brewed), 80-120

Iced tea (12 oz), 70

Hot cocoa (8 oz), 5

Soft drink (12 oz) Coca Cola, 45

Pepsi Cola, 40

Dr. Pepper, 40

Diet Coca Cola/Pepsi Cola, 40-45

Mountain Dew, 55

This entry was posted in Health.

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