Quench your thirst for knowledge about water consumption

Mar 16, 2014

We hear all sorts of recommendations when it comes to drinking water: drink 6-8 glasses of water a day, drink fluids when you have a cold and drink still water instead of flavored water or soda. All this advice is enough to make your head spin -- and your bladder swim.

This week on Take Care, Dr. Stanley Goldfarb discusses some common misconceptions about water consumption in part two of his interview. Goldfarb is a professor of medicine at the Perelman School of Medicine at the University of Pennsylvania. He has a specialty in renal electrolyte and hypertension, and is a leading expert in the topic of water consumption.

Click 'Read More' to hear the second part of our interview with Dr. Goldfarb.

People are usually worried about not drinking enough water, but what about drinking too much water? Goldfarb says it takes a very extreme circumstance to drink too much water, but it is possible, and can be fatal.

“There are several circumstances in which that’s happened. I think perhaps your listeners were aware of this poor child that was forced to drink water as a punishment by her parents and died from it,” Goldfarb said. “So, if one drinks too much water and drinks it too rapidly, you can overcome the ability of the kidneys to excrete water, which is quite robust, but it is finite.”

Goldfarb explains that when you drink too much water, the condition hyponatremia occurs. When that happens it means there is a low level of sodium in the blood because the blood has been diluted from drinking too much water.

Goldfarb warns of this possibility, which could happen to people like marathon runners, who might drink too much water during a race. But he adds that the body has a very efficient mechanism for excreting water, so this problem is typically avoided.

When it comes to consuming the proper amount of water, Goldfarb says drinking still water is not the only way to do it. Contrary to some theories, other beverages like coffee and soda contribute to hydration just as much as regular water.

“In terms of the fluid content, it’s all the same. But drinking it as coffee or tea or sodas or fruit juices or water, it’s all the same. And it really doesn’t matter except for the fact that drinking lots of sugar-containing drinks may have adverse effects,” Goldfarb said.

Goldfarb also says that even though coffee, tea and soda have caffeine, it’s not enough for them to act as diuretics. A diuretic is a substance that elevates the production of urine, and caffeinated beverages do have mild diuretic effects. But Goldfarb says that the effect is small, and that these beverages contribute to hydration just like water does.

According to Goldfarb, plenty of foods, like fruits and vegetables, can also help you stay hydrated. But he also says others, like meats, may cause you to lose a little more water.

“There’s water in many foods,” Goldfarb said. “So the diet will influence how much water that you’ll need to take in in order to replace those obligate losses.”

Goldfarb also clarifies other common beliefs about water. He says that drinking water while you have a cold could be helpful. But this is to make up for water loss, and has nothing to do with your stuffed up or runny nose.

“It’s true that individuals who have fever will tend to have more water loss through their skin than individuals who have a normal body temperature,” Goldfarb said. “But does drinking loss of water improve mucous flow? It’s unlikely. It’s not really ever been carefully looked at but it’s quite unlikely.” 

There’s a myth that drinking water before getting a blood test will help in the process of having the blood drawn. Goldfarb says this is simply untrue. He also says that is could be dangerous to drink a large amount of water right before a blood test.

Most of Goldfarb's research on water can be summed up this way: drink when you’re thirsty, and your body will get the water it needs.