The latest on hydration

Originally Published: August 20, 2004
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Dear Alice,

I frequently hear that beverages with caffeine or alcohol are not good for replenishing fluids and preventing dehydration. But in reality aren't they just a bit less effective at hydrating your body than other beverages? In other words, if you were stuck in the desert with nothing to drink but beer, coffee and cola, would you actually be worse off and die of thirst sooner if you drank these beverages versus not drinking anything at all?

Feel free to reword the question!

Dear Reader,

Let's start with the basics. Your body needs water. Water is one of the most important nutrients in the body, making up approximately 75 percent of our brain and 70 percent of our muscles. Water is essential to almost all of a body's functions. Everyday, we use and lose water through sweating, urinating, and breathing. If we do not replenish our water supply, we become dehydrated. The consequences of dehydration range anywhere from slight headaches and muscle cramping to loss of consciousness and even death.

The drinks you mention — beer, coffee, and cola — are all water based. Even though they contain carbonation and caffeine, they are still a form of fluid. So if you were stuck in the middle of a desert, you would probably last longer drinking coffee and/or cola than you would if you drank nothing at all.

Nutritionists have traditionally not counted caffeinated beverages as part of their daily fluid intake, because caffeine, similar to alcohol, is a diuretic, a substance that tends to trigger urination. In this way, diuretics can contribute to dehydration. However, during the Spring of 2004, the Institute of Medicine issued new hydration guidelines that now advise women to consume 91 ounces of fluid (2.7 liters or approximately eleven 8-ounce cups), and men, 128 ounces (3.7 liters or sixteen 8-ounce cups), and, different from before, all beverages count. The report also stated that available research evidence does not support the argument that caffeine leads to cumulative body water deficits. Approximately 80 percent of an individual's total water intake comes from drinking water and beverages, including caffeinated beverages, while the other 20 percent comes from food. The report concluded, then, that caffeinated as well as non-caffeinated beverages contribute to total fluid intake. Because not all nutritionists and other health care providers agree with the report, hydration remains a hotly debated topic.

Again, back to basics: each person's water needs is different. People who live in hot climates, exercise and/or sweat a lot, or are ill, in particular, likely need more water than the average adult. One way to determine your level of hydration is to notice the color of your urine. If it's dark yellow or orange, you may be dehydrated. Urine that is very light yellow or clear and colorless like water is a sign of a hydrated body. And if you're thirsty, drink your fluids.

Alice