Coffee, Sex, Health, & Religion

Last Update: 11 May 2007

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Coffee and Dehydration--Urban Myth

Health Benefits of Coffee

Coffee, Sex, & Religion

Problems with Coffee

Coffee and Dehydration--Urban Myth
The logic goes like this: Diuretics cause dehydration. Caffeine is a diuretic. Coffee contains caffeine. Hence drinking coffee causes dehydration. The flaw in this logic is that coffee is NOT mostly caffeine, it is mostly water. The water provides hydration, while the small amount of caffeine has negligible or no effect. Many studies have shattered the myth about coffee and dehydration, but a recent thread in the newsgroup aus.bicycles showed that the scientific evidence apparently has not have reached everyone. Again, note the importance of distinguishing between the beverage of coffee, and the substance of caffeine; the small amount of caffeine in coffee is a diuretic, but it does not somehow eliminate the hydration effect of the large amount of water, or, according to several of the studies, diminish it at all. It is a shame that some people are giving up all the health benefits of coffee based on an urban myth. There are too many studies to list them all, but I've included some of them below.
Investigations comparing caffeine (100-680 mg) to water or placebo seldom found a statistical difference in urine volume. In the 10 studies reviewed, consumption of a CB resulted in 0-84% retention of the initial volume ingested, whereas consumption of water resulted in 0-81% retention.

Wow, now it looks like caffeine increases hydration!
Q - I’ve heard that drinking tea and coffee is bad for you as they promote dehydration and so should be avoided by athletes as they harm performance. Is this true?

A - I commonly hear this question asked and the usual reply, by a well meaning person, is that tea and coffee are diuretics (lead to body water loss), contain ‘toxins’ or that you have to drink equivalent volume of water to counteract their water-losing effects. If this were true, Great Britain would be holding fewer medals  at World and Olympic level! Sometimes dietary advice persists in nutrition based on anecdotal evidence, voodoo science and myth. Conclusions are drawn on topics that seem ‘obvious’ or logical and yet have not been subjected to the rigor of scientific appraisal. Professor Ron Maughan and accredited sports dietitian, Jane Griffin, recently reviewed the scientific evidence to look at the commonly held view that tea is a diuretic and that that normal tea drinking habits are associated with poor fluid balance. 

The bottom line is that there is no evidence base in the scientific and medical literature for the commonly quoted idea that all caffeine-containing drinks should be avoided in situations where fluid balance is, or might become a problem.
The way it's almost always stated, in books, magazines and newspapers, the 8-by-8 rule specifically discounts caffeineated beverages, such as coffee. This is flat wrong. Caffeine does cause a loss of water, but only a fraction of what you're adding by drinking the beverage. In people who don't regularly consume caffeine, for example, researchers say that a cup of java actually adds about two-thirds the amount of hydrating fluid that's in a cup of water.
"For years, newspaper and magazine articles have repeated the notion that caffeine is dehydrating as if it's absolute fact," says University of Nebraska researcher Ann Grandjean, EdD. But in a study published in the October 2000 Journal of the American College of Nutrition, Grandjean and her colleagues at the Center for Human Nutrition showed that it's pure fantasy. 

The researchers looked at how different combinations of water, coffee, and caffeineated colas affected hydration levels in a group of 18 men between the ages of 24 and 39. During one phase of the experiment, the only fluid the volunteers consumed was water. During another, 75% of their intake was caffeineated. 

"Using almost every test ever devised to measure dehydration, we found no difference at all," says Grandjean.

The full study can be found at:

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"Recent research points toward the equivalent of about two or three cups of caffeinated beverages having little or no diuretic effect."

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"Unfortunately, the hydration issue got wrapped up in other issues like sugar content, aspartame side affects, phosphoric acid vs. bone calcium and caffeine; valid issues but nothing to do with hydration. Caffeine is another debunked issue. The old argument was that caffeine is a diuretic so it defeats the hydration. Recent studies have shown, however, that its diuretic effect is much less than previously thought and people who regularly drink caffeinated drinks show little affects from it. I know that’s true for me. An excerpt from the web site:

In the newer study, 18 healthy young men drank either water alone or water plus other beverages including coffee and caffeineated colas in assorted combinations. The researchers found that urine volumes had  not varied according to whether the subjects had consumed caffeinated or non-caffeinated beverages. They said the reason their findings differed from those of the earlier study was probably that their subjects had regularly consumed caffeinated beverages daily until the experiment. Other investigators have likewise suggested that the body adapts to caffeine intake so that eventually it has little or no effect on water losses."

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But studies like the one published in the 2000 Journal of the American College of Nutrition found that if you are a habitual coffee drinker, you retain practically all the liquid in every cup of coffee you drink because your body has adjusted to the slight diuretic effect of caffeine.

If you are not used to drinking coffee, your body will retain only two-thirds of every cup you drink but this is a far cry from the negative fluid loss that once was believed. Other studies have found that two to three cups of coffee a day has little effect on dehydration but six cups or more will lead to a 3 percent loss of body water.

Alcohol, meanwhile, is truly dehydrating because the body needs water for your liver to metabolize all that tequila you just drank. However, studies found that one drink won't harm you and diluted alcoholic drinks like beer can count as a fluid replacement as long as you drink moderately.
Finally, strong evidence now indicates that not all of the prescribed fluid need be in the form of water. Careful peer-reviewed experiments have shown that caffeineated drinks should indeed count toward the daily fluid intake in the vast majority of persons. To a lesser extent, the same probably can be said for dilute alcoholic beverages, such as beer, if taken in moderation.
We've all heard that caffeine is dehydrating. However, we've talked to a couple of experts who point to studies that say, you know what, when we look at it, people get just as hydrated from caffeineated beverages as they do from decaffeinated beverages. So of course you don't want to drink just caffeineated beverages all day, but if you have a cup of coffee in the morning and a cup of tea in the afternoon, you can count that as some of your water -- some of your water intake. 

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Myth: Drinking coffee, caffeinated drinks or alcohol in hot weather causes you to lose extra fluid. Coffee's not the best bet for a hot day, but it won't dehydrate you. 

People buy into this one because caffeine-spiked drinks are diuretics — hey tend to make you urinate. But drinking a cold Coke or an iced cappuccino won’t cause you to pee out much more than drinking the same amount of water. Just go easy on the frosty six-packs; alcohol has a much stronger diuretic effect than coffee or cola. Sports drinks and beverages that contain sodium are your best bets for hydration on a hot day, because sodium helps your body retain fluid.

Hopefully the myth of coffee and dehydration will someday die, but I'm not holding my breath. There are a lot of well-intentioned, but ignorant, people that are intent on perpetuating it.



Heath Benefits of Coffee
Amazingly, there are still many people that believe the old wives' tales about coffee causing all sorts of maladies. These people are either unable to open their minds or they are clinging to misinterpreted religious beliefs. For example, coffee has been shown in several medical studies to aid in weight loss. Yet you often see unqualified people who advise that coffee should be avoided during a weight loss regimen. The fact is that coffee must be taken in high doses to be effective as part of a weight loss program so there is really no effect at all for most people, but it need not be avoided. The funniest statement I saw was that coffee was bad for weight loss because you typically drink coffee when you eat a Dunkin' Donut.

An article at states that studies have shown that coffee:

An article that was at (now defunct) stated:

"Most people don't think of coffee as a medicinal herb, but it is. The beans are actually seeds of the coffee shrub, therefore an herbal product. And the caffeine coffee contains is clearly a drug. That's why the vast majority of American adults use it every morning to help them wake up. American coffee consumption is currently a staggering 10 pounds per capita annually."

Consumer Reports stated in an article:

Tea is not the only beverage that contains antioxidants. Cocoa and coffee-especially the strong brews favored by French consumers-typically have higher antioxidant activity than green or black tea, according to a study from the Nestlé' Research Center in Switzerland. (Herbal teas chamomile, lime flower, mint, rosehip, and verveine--had by far the least antioxidant power.) Coffee and cocoa are both rich in polyphenols, the same class of antioxidants that gives non-herbal tea its apparent disease-fighting powers. However, the evidence from the type of nutritional studies conducted on tea drinkers indicates that coffee and cocoa have only a tepid positive effect in humans. Other beverages that have high to moderately high antioxidant power include grape juice, red wine, tomato juice, and orange juice.

Another article about the antioxidants in coffee also cites the Nestle study:

Coffee beats green tea by containing four times the amount of health-boosting antioxidants, which can assist in preventing or postponing the onset of degenerative diseases, according to a new study. The study, carried out in Switzerland by the Lausanne-based Nestle Research Center, examined the effects of green tea, cocoa, herbal teas and coffee on antioxidant activity.

"We have known for some time from our monitoring of on-going research findings that there are many potential health benefits of consuming coffee," an official of the International Coffee Organization said in a statement Wednesday. "This latest and exciting research finding may help us better understand and prevent common diseases which are triggered by oxidative reactions." Antioxidants reduce the effects on the human body of harmful substances known as free radicals which may be a major contributor to cardiovascular disease, cancer, cataracts and decline of the immune and nervous system.

What's interesting about the Consumer Reports article is the mention of herbal teas and how they have the least anti-oxidant power. Macintosh users that drink herbal tea should be made aware of the fact that they are drinking a beverage with virtually no health benefits.

Given all the medical benefits of coffee I'd be more inclined to label it a wonder-drug! So now that most medical and nutrition experts have recognized the phenomenal health benefits of coffee, it's only natural that most cyclists want to imbibe this healthy, nourishing beverage while on the road or trail.

Practically speaking, the important thing to take away from all these studies is that certainly there are very few negative aspects to caffeine consumption while the potential benefits are enormous. Some of these benefits are proven, some are theorized from circumstantial evidence. I.e., it is a fact that non-coffee drinking men are five times as likely to have Parkinson's disease, but it is possible that something in the brain composition of the men that are more resistant to Parkinson's also predisposes them to heavy coffee drinking and that the coffee has nothing to do with it at all.

Coffee has been proven to increase athletic performance in endurance sports such as cycling and cross-country skiing, but does not appear to help in short intense sports (i.e. sprinting, weight training, see: (it's gotta be true because it was written by a Gator!).

There are health benefits in drinking real tea as well, but not in so-called "herbal tea." The same Republicans that drink flavored coffees are the ones drinking vanilla-creme-raspberry herbal tea.

The following table has links to various articles about coffee's health benefits:

Click for Link to Article

Antioxidants 1, 2
Athletic Performance
Apnea in Premature Infants (I have personal experience with this one!)
Cancer (bladder)
Cancer (colon) 1  2
Type 2 Diabetes 1, 2, 3
Endurance and Performance
Gallstones1 2
Impotence (article has expired see virility)
Heart Health
Kidney Stones
Parkinson's 1 2
Radiation Poisoning
Skin Cancer
Virility (scroll down to "Beyond Folklore: Some Scientific Substance")

Coffee, Sex, & Religion
A National Geographic article states that coffee craze started in Yemen and spread across the Muslim world. A lot of the anti-coffee crusaders were motivated by factors such as the effect that coffee sales had on competing beverages, and the fact that coffee houses were becoming more popular than other houses of worship (maybe Starbucks will next try to open outlets inside churches, mosques, and synagogues).

Ian Bersten's Coffee Sex and Health Book
There is now a book about Coffee, Sex, and Health by noted coffee historian and Jewish secular humanist Ian Bersten (aptly titled Coffee, Sex, and Health).

It's an excruciatingly detailed account of the history of coffee around the world and how it came to be regarded as a dangerous, unhealthy beverage that induced deviant sexual behavior among its imbibers.

The ISBN is 0957758103. For some reason this book is not available from the major on-line booksellers, perhaps because it is not from a U.S. publisher. Use the link below to purchase this book.

Click here to read the transcript of an Australian Broadcasting Corporation interview with Ian Bersten.

While coffee is now classified as an herb (see, many scientists believe that coffee should be classified as a vegetable (if Republicans can turn catsup into a vegetable as they tried to do during the Reagan regime, then anything is possible). What it all boils down to is that coffee is not just a beverage; experts agree that it is good food. It should be noted that like many foods, coffee should be consumed in moderation, because even good foods can be harmful when you eat too much of them.

Problems with Coffee
Like many herbal products, coffee beans contain compounds that are used in pharmaceuticals. Caffeine is the compound that concerns the most people, and there are some negatives associated with excessive caffeine use. Caffeine stimulates the central nervous system. It  can makes some people jittery. It can cause insomnia. It can cause disturbance of heart rate and rhythm.

According to an e-mail I received, there is a link between migraine headaches and coffee. I found one link at that states: "Many migraine suffers can identify single foods as headache triggers -coffee, chocolate, junk foods, and alcoholic beverages are common triggers of migraine but normal food components - milk, wheat, barley, rye, oats, corn, eggs, peanuts, soy, almonds, cashews, oranges and fish can also be headache triggers." Another article on this subject is at: This article states that "...People who have a high caffeine intake may experience headaches or withdrawal symptoms if they suddenly cease getting their normal amount of caffeine." This actually makes a lot of sense since the same reason that caffeine intake helps stop a headaches would account for why withdrawal from caffeine would cause them.

Is Coffee Linked to Miscarriages? Most studies say no, caffeine in moderation, is not linked to miscarriages, but there is one seriously flawed study that suggests a high intake of caffeine does increase the risk.

An article about the latest study which suggests a link at lower levels of caffeine consumption, can be found at: .

This study has one major flaw (and major is an understatement!). The article states: "there were differences found, however, between the two groups of women. For example, the authors note, "the women who had (miscarriages) were significantly older than the control subjects, were more likely to have been born outside the Nordic countries...and were more likely to have had previous pregnancies and previous (miscarriages)."

Talk about a significant difference! Older women are much more likely to have miscarriages and women who have had previous miscarriages are more likely to have them again. The significance of being born outside of the Nordic countries is not clear because it doesn't say which countries they were born in, but the Nordic countries have some of the best health care systems with widespread access regardless of economic circumstances. Clearly, if the statements in this article are correct, this study is virtually worthless.

In any case, it is prudent for pregnant women to take all precautions possible and eliminating coffee or limiting it to a low level does make sense.

Cardiovascular Health and Cardiac Arrhythmias
According to "there are clearly people who have serious cardiac arrhythmias (irregular heartbeat) due to caffeine consumption. We have to say that, concerning cardiovascular health and cardiac arrhythmias, some people are sensitive to the effects of caffeine. If that is true of cardiac effects, it could be true of other things."

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