I'm so relieved.

We no longer have to drink eight glasses of water a day. An recent editorial in the online version of the Journal of the American Society of Nephrology has laid that urban myth to rest. Its authors (Drs Negoianu & Goldfarb) found that there is no clear evidence behind this long held recommendation.

Now I can keep doing what I've been doing: drinking when I'm thirsty. And telling my patients to do the same. Only now I don't have to feel guilty about it.

I stopped drinking (and recommending) 64 daily ounces of water several years ago. I had heard this health tidbit early on in my medical career, though I had never seen a good study to back it up. Yet my colleagues in the nutrition field were always touting water's benefits, and it seemed reasonable enough. So ever the dutiful doctor, I passed along the advice. And I took it myself. During residency, I would carry a water bottle in the pocket of my white coat, and sip from it while going over charts or sitting in lectures. As a runner (and a breast-feeding mother, at the time), this was probably a good idea.

But after a while it became clear that large amounts of water are not a good idea in every situation. My water-obsessed patients often showed up bloated and edematous. The ones with heart disease occasionally noted that their blood pressures went up along with their water intake. Once I was no longer a busy resident (and my babies were weaned) I actually started to get headaches when I drank too much water--not to mention that I was constantly in the bathroom. So I began to question the previously sacrosanct notion that excessive hydration is healthy.

Of course, other healing traditions have questioned this notion for decades--if not centuries. In the worlds of macrobiotic nutrition and Traditional Chinese Medicine, too much water is thought to unbalance the body. We've known about the dangers of over-hydration in the Western medical world as well. Of recent interest was a 2005 study printed in the New England Journal of Medicine. This study found that found Boston Marathon runners who drank too much water were at risk for potentially harmful hyponatremia (low sodium levels): "The strongest single predictor of hyponatremia was considerable weight gain during the race, which correlated with excessive fluid intake." Hyponatremia can cause a myriad of significant problems, including brain swelling and death.

There is no need for hyponatremia, or dehydration, for that matter. Our bodies known what we need, as long as we are willing to listen. When we are thirsty, we can drink. When we are not, we can stop.

And we will stop needing to run to the bathroom every ten minutes to rid ourselves of excess fluid.

Which is, itself, quite a relief.

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