In a previous post, I talked about how that I am absolutely convinced that when I don’t drink enough water, I get headaches and don’t sleep well at night, even if some scientists disagree with that assessment. Here is a lengthier discussion on that.
Since the article wasn’t freely available, I can’t look at “all the studies” on headaches and dehydration or water intake, but I will say this: What if some of the studies looked at daily water intake of one liter or 1.5 liters? A liter is a little more than a quart (32 oz.), so if some studies suggested drinking two liters, but most study participants only took in one liter or 1.5 liters, then that was less than 64 oz. Also, for some people, drinking 64 oz. may not be enough.
One potential problem I see with this research — assuming it to be accurate and non-biased — is the “one size fits all” mentality which does not take into account individual characteristics of study participants. I one time heard it described this way — assume there are 99 random men in a group — what would the average net worth be? Now add Bill Gates into this group, and then what would the average net worth be? Even if all 99 men were about to file bankruptcy for having a negative net worth, Bill Gates’s huge positive net worth would be enough to counteract their millions of negative net worth. In the same way, some medications or procedures (or drinking water) may have minimum risk or benefit for the average population, but may have huge complications or benefits for a few people. The original discussion that I took the above Bill Gates reference from was about Vioxx — that most people had little or no benefit from the drug (compared to already available drugs for arthritis), while a few people had tremendous benefit, which skewed the statistics in the early studies. Add to that, that when it was released to the public at large and millions of people took it, a few had tremendous negative effects (such as heart attacks), that then skewed the statistics about the risk. I’m not minimizing heart attacks — just saying that most people who took Vioxx will have no problems with it, but a few will have major problems. In a similar way, drinking 64 oz. of water may not be a magic cure for society at large, but a few may receive significant benefit from it — like me with headaches and insomnia, or my mom for high blood pressure.
My mom is 60, and last year happened to find out she has high blood pressure. (I’m not sure how she figured this out, since she doesn’t go to doctors, but maybe on a fluke she had somebody take her blood pressure.) Anyway, she bought herself a home blood-pressure monitor, and discovered that her blood pressure was consistently on the high side. Her chiro suggested she drink a gallon of water per day. She thought she drank a lot to start with, but when she filled her gallon pitcher with water in the morning, and drank from it all day (to keep track of how much she actually drank), she was surprised to find it difficult to drink more than half of it. She kept up with it, though, and started drinking the full gallon, and within a couple of weeks, her blood pressure had dropped to normal — without any medications, or changes in diet or exercise (although she walks several miles a day). One gallon is 128 oz., or double the “recommended daily minimum” that the above researchers supposedly debunked.
But while I couldn’t get so much as an abstract for the above-mentioned review of studies, I did find at least a couple of small studies which seem to indicate that there are benefits for some people in drinking more water than average.
This study concludes, “Water-deprivation headache is common, recognized by the public, but not described in the medical literature.” Do click on the link and read the whole thing, because I think it is quite eye-opening, even if it is just an abstract. It also demonstrates that just because something hasn’t been studied or described in medical literature, it doesn’t mean that it doesn’t exist. In fact, the doctors were surprised at how frequent mentions of this link between water deprivation and headache occurred on the internet. While this study pre-dates the above-mentioned review (and would have been supposedly included in the review which finds no benefit to drinking water), my personal experience leads me to believe this study. The abstract says that 10% of people in the group had experienced a headache caused by a lack of water. Which means that 90% of people did not. So while the “average” person in the group did not experience a water-deprivation headache, for those who did, drinking a glass or two of water remedied it.
This small study on migraine patients showed some benefit to drinking water — a decrease in the severity of migraines as well as fewer total hours of headache pain — and suggested that a larger study would be in order.
I tried to find other studies (Google Scholar, “water, headache”), and most of the links talked about things like swimming, hot baths, or medications dissolved in water (which didn’t discuss drinking water), or didn’t have enough information on the link (no abstract, etc.). I wish I could find more studies, to see which ones the above-mentioned reviewers found which concluded no benefit to drinking two quarts or more of water; but in the meantime, I will continue to drink a lot of water, because although it may not have benefits for the general public, it certainly has benefit for me.
However, just as in everything, there can be “too much of a good thing.” There is something called “water intoxication” — it is possible to drink too much water. I think the generally accepted idea is that the kidneys can clear about 3 gallons of water per day, which seems an impossibly high amount of water to drink, but I know it has happened, so use common sense in this as in everything else.