Quench Your Thirst
by Dana Denis, MSPH., RD (topic expert: nutrition)

How much water does it take to quench your thirst? Eight glasses a day? Does it have to be water? How about caffeinated beverages, sports drinks and carbonated beverages? Can you drink too much water? What does the most current research show?

The Institute of Medicine answered these questions and others in a review of all available research on water and hydration. They came up with the following guidelines. Most individuals can maintain proper hydration by drinking when they are thirsty.

• In general, women need approximately 11 cups of fluid per day and men over 15 cups of fluid each day.
• Approximately 80% of our fluid intake comes from beverages; the remainder comes from the food we eat.
• When food is taken into account, women should drink about 9 cups of fluid per day and men 13 cups a day -- but again, many factors affect hydration and you should drink to quench your thirst.
• Does it have to be water? No. Even though water is the perfect replenishing fluid in most situations, all fluids contribute to hydration.
• What about caffeinated beverages? Previously, caffeinated beverages were excluded from the hydration equation. This was based on the assumption that caffeine acts as a diuretic and promotes excessive fluid loss. Recent studies show that this "diuretic effect" is transient and is not present when caffeine is consumed on a regular basis. Therefore, that cup of coffee in the morning counts too!
• What about carbonated beverages? Those bubbles do not exclude these beverages from counting towards your fluid replacement. In fact, if carbonated water tastes better to you, then you might drink more of it! Watch out for the waters and sodas with added sugar and therefore added calories.

The above statements are only recommendations, as many factors affect our fluid needs. For example, you may need more fluid if you live in a hot climate or have a high activity level.

When I am walking or exercising should I drink water or a sports drink?The answer to this depends on the duration and intensity of the activity and the climate. If you are doing vigorous exercise for over one hour, having fluids with added sodium and potassium, as well as some carbohydrate (glucose, dextrose, sucrose, and fructose) may be beneficial. This will replace sodium and potassium loss from sweat, as well as a small amount of the carbohydrate lost during exercise.

Can you drink too much water? Yes. More is not necessarily better. Too much water can cause the sodium in your blood to become diluted and drop dangerously low, which is called hyponatremia and can even lead to death. This is seen primarily in athletes trying to keep hydrated during long exercise events.

Avoid high calorie-nutrient poor fluids. Of course water is the best hydration fluid in most circumstances, but if you do not like drinking water be assured that other beverages do contribute to hydrating your body. BE CAREFUL! Especially if you are watching your calories, you want to make smart choices. Avoid high calorie sodas (about 12 calories per ounce). Even though juice can provide great nutrition, too much also leads to excessive calorie intake (about 15 calories per ounce). Even some waters will contain sugar - read your labels.

To increase your fluid intake:

• Try adding lemon or lime to your water or add a small amount of fruit juice for a little added flavor.
• Eat foods that contain significant amounts of water. Some examples are lettuce, broccoli, watermelon, citrus, apples, carrots, and yogurt.
• Try skim milk and get the bonus of added calcium and vitamin D.
• Have a bottle of water with you - make it easier to reach for water instead of a soda.

Watch for signs of dehydration, such as dry mouth or dark urine. Before exercise, be sure you are hydrated. During your activity, try to replace fluid losses. The amount depends on the duration and intensity of the workout and the climate. After exercise, don't forget to drink and replenish your body.

Drink when you are thirsty to quench your thirst and you should provide your body enough fluid to meet your daily needs.

References:

1. National Academy of Sciences. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride and Sulfate. Available at www.nap.edu/catalog%2010925.html; 2004.
2. American Dietetic Association Website: www.eatright.org/.