May 18, 2007

You Ask, I Answer: Water

Do we really need to drink 8 glasses of water a day?

-- Derek Naughman
Minneapolis, MN

This is undoubtedly one of the most prevalent nutrition myths.

This all stems from a scientific report which concluded that humans need approximately 64 to 75 ounces of fluid a day.

The mass media reported this as "64 ounces of water a day," completely oblivious to the fact that said figure accounted for water present in the food we eat as well as beverages other than H2O (milk, coffee, tea, soda, juice, etc).

If the food we ate was lacking in water, it would practically be impossible to swallow it. Granted, some food (cucumbers, watermelons) offers more hydration than others (peanut butter).

Yes, you read correctly -- coffee contributes to that water figure. Some of you might be confused, since caffeine, a natural diuretic, dehydrates.

Many clinical research trials, however, have shown that regular coffee drinkers' bodies get used to the caffeine intake and their fluid loss, if any, is minimal.

While it is possible that a new coffee drinker may need slightly more hydration, after a few months of drinking 2 cups of coffee a day, his body will not need to replenish the fluids once lost to caffeine.

Of course water is one of the best beverages you can have, since it is free of added sugars, artificial sweeteners, and calories.

However, milk (dairy or soy) offers calcium, protein, and vitamin D, while tea and coffee offer some great antoxidants.


Simply put, drink when you feel thirsty and you'll be just fine. This will most likely vary with context. You will drink more fluid if you are exercising, and will feel more thirsty in summer than winter.

If your thirst only requires 4 or 5 cups of liquid a day, so be it. Don't force water down your throat because "you have to drink 8 glasses a day" (you don't!). If any "expert" references the "8 glasses of water a day" figure as dogma, feel free to correct them.

As for that myth claiming that by the time we are thirsty we are actually dehydrated -- absolutely not true. Thirst and dehydration happen under very different conditions in the body.

Older people need to be increasingly aware of staying hydrated, though, since humans' thirst mechanism loses efficiency with age.

1 comment:

Anonymous said...

When did this myth get started and how? Seems like for the past 7 yrs friends started talking about it. But just before that bottled water became a trend to carry around. Please tell me it wasn't the bottle water companies who started this! You're suggesting, "drink water when you're thirsty" sounds unique, but hey, that's how I grew up.
R from Ohio