What's to drink?

Water has become quite the fad in recent years. Its popularity is demonstrated by entire aisles being devoted to it in grocery stores. Who would have thought that the most basic of fluids would come in so many forms?

The attention is well-deserved as water is vital to health—and life itself. It is one of the body's most essential nutrients. Although it may be possible to survive for six weeks without food, you cannot live longer than one week or so without water.

Most abundant substance on earth…and in your body
Not only is water the most common substance on earth, it is also the most abundant substance in the human body. On average, human body weight is 50 to 75 percent water—or about 10 to 12 gallons of water. The specific percentage of water varies from person to person—affected by body composition, age and gender, among other factors.

Because the proportion of water in each of our bodies is different, it makes sense that water needs also vary from person to person. Generally speaking, most people need eight to 10 cups of water daily. Be aware that fluid needs are affected by a variety of factors.

Factors affecting fluid needs

• When exposed to extreme temperatures—very hot or very cold—your body uses more water to maintain its normal temperature.
• During strenuous work or exercise your body loses water through perspiration or evaporation from your skin.
• When you are exposed to heated or recirculated air for a long time (i.e., airplanes), water evaporates from your skin.
• Pregnancy and breastfeeding increase the amount of fluid a woman’s body needs.
• Fever, diarrhea and vomiting cause increased water loss.
• High fiber diets require extra water to process the additional roughage and prevent constipation.

The average adult loses about 10 cups of water each day through perspiration, the kidney/bladder system, bowel movements and the respiratory system which must be moist or breathing would be painful. Adequate hydration is very important in maintaining body temperature. The human body does not store an extra supply of water for those times when you need more.

Nearly all of the biochemical reactions that occur in body cells depend on water and electrolyte balance (sodium, potassium, calcium, chloride, phosphorus, magnesium, etc.). These balances are not only vital to maintaining life, but also affect physical and mental performance.

Feeling thirsty?
Thirst is a physical sensation signaling to you that your body needs more fluid to perform its functions. However, we should not wait until we are thirsty to drink. By the time our body sends us the thirst cue, we are already on the pathway to dehydration. Be aware that while thirst is a powerful indicator for most people, the signal may not be as strong in the elderly and children or during illness, hot weather and strenuous activity.

What do you reach for when you are thirsty?

Sports drinks
Believe it or not, the optimal drink for many sports activities is water! Sports drinks are meant to replace fluids, supply calories for energy and replace sodium and potassium lost through perspiration. Most athletes don't need a sports drink unless they have exercised for an hour or more. Even then, the body mainly needs fluids. However, if you are more likely to drink a sports drink rather than water during physical activity—then do it. Be aware that these drinks contain sugars, so they also supply calories.

Soda and alcohol
Coffee, tea and some soft drinks are not your body's best sources of water. Caffeine and alcohol act like diuretics, causing the body to lose water through increased urination. Decaffeinated beverages, however, do not have the same water-shedding effect.

Juice
Many are under the assumption that juice is a better option than other fluids because of the vitamins it provides. Beware that while juice can be a good source of vitamins, it is also a good source of concentrated calories. It may be wise (and more filling!) to get those vitamins you seek from the whole fruit itself—in addition, the calories are not as concentrated.

Flavored water
Do you get bored with plain water? Consider one of the many flavored water products on the market. Most flavored waters contain artificial sweeteners that do not contribute to calories but add a twist on taste! Be sure to check out the Nutrition Facts. Want the taste of flavored water without paying the high price? Consider adding a lemon slice or berries to water.

The Yale-New Haven Nutrition Advisor is created by registered dietitians and dietetic interns who staff the Nutrition Clinic at Yale-New Haven Hospital. For information, contact the Nutrition InfoLine at (203) 688-2422.

For more information on this topic, you could visit:

• Summer: Find out about fiber and fluids, Nutrition for Active Adults, Yale-New Haven Hospital
• Dehydration, Pediatric Services, Yale-New Haven Children's Hospital
• Dehydration
• American Dietetic Association
• Water for health and performance, L. Lee Coyne, PhD
• Hydration and fluid needs, about.com

Other issues addressed by Yale-New Haven Nutrition Advisor:

• Obesity—it's not just for grown-ups anymore
• Fruits and vegetables: Always in season
• Calcium: Not just for bones anymore!
• Mercury Rising
• A powerful B vitamin: Folate
• Vegging out
• Manic for organic
• Beta carotene
• Shellfish & cholesterol
• Sorting through nutrition information
• Summer fruit sensations
• Make it fun in the sun (outdoor food safety tips)
• Archive

Last revised: March 10, 2005 (jj)

Home page URL: http://www.ynhh.org

All information is intended for your general knowledge and is not a substitute for medical advice or treatment for specific medical conditions. You should seek prompt medical care for any specific health issues and consult your physician before starting a new fitness regimen.