Extension Connection

Drenching the Water Myths
By Janet Hackert, Nutrition Specialist

Water is an essential nutrient, yet there may be some misconceptions about it. The July 2008 issue of Tufts University Health and Nutrition Letter dispels some of these myths.

Water is crucial for human life. Blood is, on average, 92% water, and other parts of the body, such as muscles and brain, are 75% water. Water is needed to control body temperature, to lubricate and cushion joints, to transport nutrients, and to remove waste.

But there are myths about water that have been drenched. Here are some of them.

Myth:  People require eight 8-ounce glasses of straight water daily. In fact, in 1945, the Nutrition Council found that people do need approximately 64 ounces of water every day. But that water can come from straight water or other beverages like milk and juice. It can also come from foods. Some foods’ water content is more obvious than others’. For example, it is no surprise that watermelon is 91% water by weight and grapefruit is 89%. Broccoli is also 89% water by weight and carrots are 88%. Roasted chicken with no skin is 65% and even whole wheat bread is 38%!

Myth:  Caffeinated beverages, such as tea, coffee and caffeinated soda or pop, don’t count in getting enough water for the day. Actually, caffeine does have a diuretic effect (that is, it draws water from the cells), but a person would have to consume a huge amount for this to take place.

Myth:  By the time people feel thirsty, they are dangerously dehydrated. In a healthy adult, thirst comes when blood is concentrated by about 2%. “Dehydration” is defined generally as concentration by about 5%. According to the Institute of Medicine, “Fluid intake, driven by thirst… allows maintenance of hydration status and total body water at normal levels.” So drinking to satisfy thirst works to maintain that balance. A caution would be for older adults for whom the sensation of thirst does not kick in as quickly. Especially on hot summer days (or cold, dry ones), older adults should be a little more conscientious about staying hydrated.

Sources: Tufts University Health& Nutrition Letter, July 2008, p 4-5; ADA Food and Nutrition Guide, 3^rd Edition, Roberta Larson Duyff, 2006, p 157; Nutrition Action Healthletter, Center for Science in the Public Interest, June, 2008, p12-13.

(Written July 4, 2008)

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Extension Connection Barb Ubben, Web Manager harrisonco@missouri.edu Last revised: 05/25/04