The Doctor Weighs In

By Dov Michaeli MD, Ph.D

The response to the editorial by Dan Negoianu and Stanley Goldfarb on medical myths which we covered in a recent posting is absolutely amazing. Several people jumped to the defense of drinking 8 glasses of water a day. But the vehemence of the comments proved my point: the less light the more heat. None of the comments actually cited real evidence.

But one comment from Kurdistan was absolutely hilarious, so I am going to share it with you the reader. My comments in italics.

Dr Mohammad Shaikhani, a consulting physician in Sulaimanyah, in the Kurdish region of Iraq , writes:

“Other medical myths common among our local populations, having no sound scientific basis & include:

1. Acidic food such as lemon is good for hypertension.

On the other hand, the myth that acidic and  spicy foods cause stomach ulcer is still widely believed in the Western world.

2. Bitter food is good for diabetes.

Hmmm. How would that work? One likely mechanism is that the food is so unpalatable that  diabetics would refuse to eat, and lose weight. I am not kidding. Several substances, when mixed with mouse chow, were shown to “cure” diabetes in mice. Such pablum was actually published in scientific journals. Closer examination (and better controls) showed that the mice simply avoided the food because it was disgusting to them.

3. Honey & dates are safe for diabetics.

So this is why this delicacy is featured so prominently in the bible. In my naїveté I thought that my Rabbi’s claim that the Jews had diabetes when the rest of the goyim where still climbing trees was just rank chauvinism. Sorry Rabbi, wherever you are.

4. Typhoid & measles patients should not eat yogurt.

Maybe, how would we know? I have never seen a case of either typhoid or measles, let alone a yogurt-eating, typhoid-stricken one. 

5. Typhoid, measles & influenza patients should not have a bath until cured.

Now this makes perfect sense; these are highly contagious diseases, and one way to control their spread in the population is make the patient  unbearably odoriferous . One would think, though, that between avoidence of yogurt and stinking to high heaven typhoid and measles should have beeen eradicated in Kurdistan a long time ago.

6. Jaundice clears by looking at moving fish in water.

I actually did it once, and I felt so mentally numb that I fell into deep stupor.

7. Whooping cough can be cured by passing through tunnels.

And while you are at it, beware the light at the end: if the whooping cough didn't get you-the oncoming train will.

8. Inhalers for asthma are addicting.

I did notice the latest fad supplanting glue sniffing: inhaling steroids. Congress should definitely hold hearings.

9. Garlic prevents heart disease & lowers blood pressure.

How multicultural; this belief was actually propagated by some villages in Italy that specialize in growing garlic. And have you heard of the garlic festival in Gilroy, CA? Only the odor will cause your blood pressure to plunge to dangerous levels; some visitors actually faint. I must admit that the garlic cult is quite universal. My parents, coming from Eastern Europe, believed in the curative powers of garlic as well. In fact, my maternal grandmother cured my mother’s colds by smearing crushed garlic dissolved in hot oil on her chest. It worked every time: after 3-4 days the cold miraculously disappeared. My father scoffed at this primitive concoction. In his more educated family, they smeared melted pig’s fat (I kid you not) on his chest, to cure his pneumonia. He swore by it; in fact, this "cure" started his lifelong love afair with bacon.

So who are we to laugh at the Kurds? When it comes to medical myths, we are all Kurds.

By Dov Michaeli MD, Ph.D

A recent editorial in the Journal of the American Society of Nephrology reviewing all the evidence to back up the claims of “drink 8 glasses of water a day” drew my attention to the whole subject of “medical myths”. Every physician could attest to episodes of irate true believers refusing to accept any criticism or skepticism. To my astonishment, I came across many physicians who vehemently believe in those urban myths. It is a curious observation of mine: There exists an inverse correlation between the amount and quality of the evidence and temperature: the less light the greater the heat. It is as if you attacked a central tenet of their beliefs, shaking up their view of the world. Even in scientific meetings I have witnessed many heated arguments, where hand waving and personal insults were  substitutes for solid data.

So with this in mind, I am going to put my life on the line and try to debunk as many medical myths as come to mind. Feel free to send poison mail. Or maybe, if you can think of a myth, email me and I promise to protect your identity.

The claims that drinking 8 glasses of water a day is good for you

There are numerous claims of health benefits of drinking lots of water, but the most oft-repeated ones are:

· It increases your skin tone, keeps it hydrated, and gives it a youthful appearance.

· It washes out toxins accumulating in the body.

· It suppresses appetite and aids in weight-loss diets.

· It prevents sports injuries.

· And finally, the blanket claim: it increases longevity.

Where did those claims come from?

Here are some fascinating historical findings, some of which I found in Slate Magazine’s The Explainer column by Nina Shen Rastogi:

•  How long was this myth around? Answer: the 8x8 (eight 8 oz glasses) myth going all the way back to 1796, in a German text by Dr. Christoph Wilhelm Hufeland called Makrobiotik. The book includes an anecdote about the surgeon general to the king of Prussia, a vibrant 80-year-old man who had "contracted the habit of drinking daily from seven to eight glasses" of cold water and thus "enjoyed much better health than in his youth." (An English translation of this book was published 1843.)
• Fast forward to the 19^th century: The hydrotherapy craze that swept through Europe and then America in the late 19^th century encouraged the notion that people needed to be drinking more water.
• By 1900, the New York Evangelist reported that a women's association on the Lower East Side was being instructed by a Dr. Vinton that one needed to ingest "at least eight glasses of water a day" and take "four times as much water as food." (Incidentally, the girls were also told that it was dangerous to get one's feet wet, that it wasn't good to "wear many skirts," and that their brains were "soft like jelly."). Well, what can you expect from an evangelist, especially from New York ?
• By the 1910s and 1920s, the popular press was full of exhortations to consume six to eight glasses on a daily basis. Charles Atlas, the bodybuilder, was fond of recommending the same amount.

Who can argue with such authoritative sources?

But now for something a bit more authoritative: the U.S. government's Food and nutrition Board. The board's "Recommended Dietary Allowances" from 1945 include the following advice:

“A suitable allowance of water for adults is 2.5 liters daily in most instances. An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods.”

 What the popular, and less popular press, missed was the last sentence, which pointed out that you can get most of that water just by eating. If you actually had to drink all 2.5 liters, you'd need around 10 8-ounce glasses per day.

In more recent decades, there have been plenty of proponents of the 8x8 theory. In 1967, Dr. Irving Stillman, one of the earliest advocates of a high-protein, low-carbohydrate diet, insisted that his followers drink eight glasses of water a day in order to wash away ketones, or "ashes left in the furnace." This doctor, his financial success notwithstanding, would have failed my biochemistry class at UCSF.

The controversial 1992 bestseller Your Body's Many Cries for Water, which calls for a minimum of eight to 10 glasses of pure water a day (not coffee, not soda), probably played a role in spreading the myth, as has the bottled-water industry, which has exploded since the 1980s.

And the scientific evidence?

In a word: none.

The key to debunking these claims is actually in that last sentence of the U.S. Food and Nutrition Board statement of 1945, namely you can get most of your water requirements from food. We can get a bit more scientific about it and point out that animal and plant cells are made up of mostly water. Surprising? The cell cytoplasm is made of a gel, something akin to gello. Did you know, for instance that cucumbers are over 90% water? And so are many other vegetables and fruits.

How much should we drink?

The short answer is: as much as you feel you need to drink. Of course, if you exercise a lot, or live in a warm climate you need to drink more. But don’t sweat it—your body will signal its needs for hydration through dry mucous membranes in the mouth; or if deficit is more pronounced—through orthostatic hypotension, which means a drop in blood pressure when you stand up from a sitting of lying position. You don’t have to measure your blood pressure for that—you will know it when you experience it: you’ll feel dizzy. And if these two signals fail to alert you, pay attention to your urine. If you notice a marked decline in volume and the color turning deeper yellow, it is a signal that your body is trying to conserve  water. Time to replenish the tank.

And yes, coffee, tea, soda—they all count as fluids. The myth that these don’t count because they are diuretic is just that—an undocumented belief.

Take home message

First, don’t believe what you hear. Ask for the evidence; you’d be surprised by answers like “everybody knows that”, or even worse.

And second, for all you H2O guzzlers, take it easy. Drink as much as you feel like, and chalk up rest to water conservation.