Don't get me wrong -- water IS good for you. Every expert who talks about healthy eating says to make sure that you drink plenty of water throughout the day. But, recently it has been made very clear that drinking too much water can actually be quite dangerous. In fact, it can kill you.
You may remember the story about the California disc jockeys who ran the "Hold Your Wee for a Wii" promotion; this was an incredibly dumb stunt where contestants drank water in the radio station studio to see who could hold it the longest in hopes of winning a Wii video game console. One of the final contestants, a young mother of 3, died the next day due to the amount of water she drank.
This problem is back in the news today. Hyponatremia is a concern because it occurs on a regular basis in marathon running, and there are nearly 40 marathons being run from Honolulu to Cape May County, NJ in the next three months. It affects a lot of runners and the frightening part is that many don't know they have it until they become very sick.
“This condition, hyponatremia, occurs when you have low sodium in your body,” said Dr. James Muntz, internal medicine service chief with The Methodist Hospital in Houston. “When sodium levels drop in the fluids outside the cells, water will get in there and attempt to balance the concentration of salt outside the cells.”
As Muntz describes it, this abundance of water will cause the cells to swell. While most cells can adapt to change, the brain cannot. Symptoms of hyponatremia include vomiting, loss of appetite, headache, restlessness/fatigue, an abnormal mental status (hallucinations, confusion, change in personality) as well as muscle weakness and convulsions.
You can prevent hyponatremia several days in front of the race by using sports drinks during training and increasing your salt intake.(This last recommendation only if you don't have high blood pressure).
“During the marathon a good rule of thumb is to drink about one cup of fluid every 20 minutes,” Muntz says. “Drinking any more than that over the course of the race can get you into trouble.”
A study of runners had been performed after the 2002 Boston Marathon. It found that 13 percent of those who finished the race developed hyponatremia, with the majority of these affected runners "feeling fine” after the race. However, if someone who feels “fine” continues to drink water because they believe the nausea and weakness they are feeling is due to dehydration, they could easily end up having a seizure and falling into a coma.