The “Drink 8 Glasses Of Water A Day” Myth And Dehydration Debunked. Part 2

(DougCookRD.com)

 

In Part 1, I reviewed some of the more popular (and unfounded) reasons for the ‘Drink 8 glasses of water a day’ myth and gave a quick overview of fluid balance in human health. In this post, I’ll look at the historical evidence that led to this myth a discuss any possible down sides to drinking all that water.

 

A look back on the history of dehydration and expanding industries

The recommendation to drink lots of water as a cure-all for dehydration and disease dates back to the 19th century and the practice of hydropathy, developed by Vincent Priessnitz (1799-1851). He not only advised his patients to drink excessive amounts of water as a way to flush out the “disease-causing offending agents”, but to also sit under cascading waterfalls and partake in sitz baths (sitting in hip deep water).

 

A strong proponent of this practice was an Australian hygienist John Hern who considered water drinking as “one of the most valuable curative agents of the time” according to Spero Tsindo, member of the Faculty of Humanities and Social Sciences from La Trobe University, Victoria, Australia, who wrote a review on the water guzzling dogma. Hern’s method of hydropathy required his patients to drink the equivalent of 1.1 to 1.7 liters of added water each day to prevent dehydration (before it strikes!); an amount that has persisted until today.

 

As I alluded to in Part 1, all myths have an element of truth at their core. To offset normal water losses, we need about 6 cups of added fluid per day. Whether its 6 cups or 8 cups isn’t the point but rather that the recommended amount refers to added fluids, or dietary fluids, and dietary fluids are mostly made up of, you guest it, water. Somewhere in the past, in the recesses of nutritional history, the ‘added fluid’ message was misinterpreted, and exchanged for, water.

 

The rest, as the saying goes, is history. People have been lead to believe that they need to drink about 8 cups of water on top of all the other sources of fluid in the diet such as tea, coffee, juice, soup, or liquids added during food prep like milk or milk alternatives. More recently, you can add fresh pressed vegetable juices, or even the trendy coconut water, which are all the rage now, to the mix.

 

And I’d also like to put to rest, once and for all, the myth that caffeine-containing beverages lead to dehydration. This has NEVER been supported by research in a meaningful way. Any minuscule amount of increased losses due to moderate caffeine consumption will be offset by the kidneys which tightly regulate water/fluid balance. The kidneys’ primary role are to maintain the body’s fluid balance followed by excretion of wastes and the production of 2 key hormones: active vitamin D and erythropoietin (for red blood cell production).

 

The burden of proof is on anyone who touts the myth that caffeine will rob you blind of your body’s precious water and led to dehydration: where’s the evidence? Anyone?Aluminum water bottle_VPZ Design

 

Are there any special interests behind the ‘drink more water’ message?

Maybe. Thirty or so years ago we didn’t see bottled water anywhere now it’s a multi-billion dollar industry and we’vegot the endless shelves in the beverage aisles and our over-stuffed landfills to prove it. Don’t use plastic? Maybe you’re one of the people with the ubiquitous trendy water bottles that you refill and carry with you everywhere. I can’t remember the last time I was at a meeting where almost half the attendees didn’t come with their faithful water bottle companion; dutifully taking several sips of water during the course of a 45 to 60 minute meeting. Where is all that water going? We only lose about 500 ml, or 2 cups, via breathing and perspiration per every 24 hours, not in 45 minutes!

 

Be sure you’ve bought the right kind though; your water bottle carries with it new found status, unless of course it’s made from inferior plastic with the evil-du-jour BPA.

 

Does drinking too much water have a down side?

Are there any unintended consequences of the ‘drink half your weight in water’ message besides all of that diluted, watery urine and trips to the bathroom?

 

A qualified yes.

 

Under normal circumstances the minerals [potassium, sodium, magnesium, chloride etc] inside and outside of your cells, including your blood, are at a perfect concentration. The fluid outside of your cells is normally higher in sodium and your body likes it that way. Drinking copious amounts of water can cause the sodium concentration outside of your cells to decrease because the excess water dilutes it; a condition called hyponatremia, or low blood sodium. In response, water moves from the blood into the cells to try and fix this undesired dilution of the blood.

 

Who cares? You should.

 

Under extreme cases hyponatremia can lead to seizure and death; rare but not impossible. Smaller, less obvious consequences, of chronically lower sodium concentration/excess water consumption can include:

  • Poor sleep quality
  • Fatigue
  • Muscle spasms
  • Headaches
  • Urgency to pee in the middle of the night
  • Frequent urination
  • Low body temperature
  • Cold extremities (hands, feet)

 

The negative impact of chronically mild hyponatremia is covered in great detail by health researcher Matt Stone at 180 Degree Health; a site that, as the name implies, takes a 180 degree view on health and nutritional conventional wisdom. Be prepared to be taken to the edge of your nutritional knowledge comfort zone; I was, and continue to be, as I learn about research and concepts that I’d never learned about in mainstream nutrition education or a traditional dietetic internship.

How much water should you drink?

Water. Is it good or bad?

Mild water intoxication. Podcast

Your body is mostly water. Well, not exactly

 

 

What’s the bottom line already?

Know this; there is nothing magical about plain water from whether it’s from the tap, or bottle, than the naturally occurring water in food or other beverages. Water is water and as long as you’re in fluid balance, you’re ‘solid’ as they say.

 

Let thirst be your guide; drink when you’re thirsty just like you eat when you’re hungry. If you need more water, from any source, your body will let you know.

 

To drink water constantly throughout the day to ‘prevent’ dehydration is as logical as eating throughout the day to prevent hunger. The body has a sophisticated and eloquently designed ability to regulate its water requirements and fluid balance under normal conditions (scheduled hydration during training and intense exercise is a different context) has been working for the human race for hundreds and hundreds of thousands of years; it’s the same basic system that works in animals as well who do just fine without having to be told to drink.

 

If I have to chose between a ‘health guru’ and my body’s innate ability, an ability that has enable the human race to survive, you can guess where I’m gonna put my money.

 

References

Gardner EJ, Ruxton CHS, Leeds AR. Black tea – helpful or harmful? A review of the evidence. Eur J Clin Nutr. 2006;61(1):3-18.

Grandjean AC, Reimers KJ, Bannick KE, Haven MC. The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration. J Am Coll Nutr. 2000;19(5):591-600

Heinz, V. “Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 × 8”?  American Journal of Physiology – Regulatory, Integrative and Comparative Physiology Published 1 November 2002Vol. 283 no. R993-R1004.

Paque, C. Water consumption in Saharan nomads. A remarkably reduced and constant consumption. Nouv Presse Med. 176;5(32):2087-90.

Maughan RJ, Griffin J. Caffeine ingestion and fluid balance: a review. J Hum Nutr Diet. 2003;16(6):411-20.

McCartney M. Waterlogged? BMJ.2011;343:d4280. PubMed PMID:2175074.

Tsindo S. What drove us to drink 2 litres of water a day? Australian and New Zealand Journal of Public Health. 2012;36(3):205-207

Walter F., PhD. Boron (2005). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders. ISBN 1-4160-2328-3. Page 829.

Whorton JA. Nature Cures: The History of Alternative Medicine in America New York (NY): Oxford University Press:2002.

Photo credit: VPZ DesignsSandeep Singh Thukral

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