Dear Mr. Dad: This summer is shaping up to be a hot one and I'm concerned that my wife and kids (and probably myself) aren't drinking enough water. How much should we be drinking and why is it so important (I need facts to convince the skeptics in the family)?
A: You've probably heard that we should drink eight 8-ounce glasses of water every day. Unfortunately, there's no hard science behind that number, but it's a good place to start. On a relatively mild day, we lose two to three liters (8-12 cups) of water simply by breathing, sweating, urinating, and digesting. Men are on the higher end of the scale, women on the lower. If you exercise regularly or spend time in hot climates, you'll need even more just to stay even.
Symptoms of dehydration range from mild (headaches, poor concentration, dry mouth, constipation, lack of energy, dry skin, and irritability) to severe (dizziness, rapid heartbeat, muscle spasms, shriveled skin, sunken eyes, confusion, and even death).
Keeping track of your water intake and monitoring your symptoms is important. But a far easier way of determining whether you're properly hydrated is to simply look at your urine. Unless you've just taken some vitamins, urine should be clear or very pale yellow. If it's dark yellow or has a strong odor, you're probably dehydrated.
Water plays a key role in digesting, absorbing, and transporting nutrients and in safely eliminating toxins and waste from our systems. It helps cushion our joints and protect our organs. Not getting enough of it has consequences. Here's what research tells us:
– Kids are more susceptible. Since children often don't recognize when they're thirsty, they're at higher risk of becoming dehydrated.
– Fluoride. Fluoride (which many municipalities add to the water supply) can help prevent cavities and tooth decay. Fluoride is typically found only in tap water, not in bottled water.
– Healthier teeth and gums. Saliva, which is mostly water, is critical to maintaining good oral health because it washes away food particles, acids, and bacteria that can cause cavities or gum disease. Even minor dehydration can have a major impact on salivary gland function.
– Better digestion. Drinking water before, during, and after meals helps the body break down our food. That means nutrients get where they're supposed to more efficiently. It also means less constipation.
– Body temperature regulation. Sweating cools us, but if we don't replace the water that's lost, body temperature will rise. That's why it's important to drink extra water before, during, and after working out, and throughout the day in hot climates.
– Better brain- and mental health. Not getting enough water is associated with reduced short-term memory, cognitive function, focus, alertness, concentration, mood, as well as an increase in confusion and anxiety.
– Better physical health. Staying properly hydrated has been linked with reduced risk of exercise-induced asthma, urinary tract infections, hypertension, heart disease, and other conditions.
– Better physical and mental performance. Athletes can sweat away 4-10% of their bodyweight in a single workout. But even smaller water losses can drastically reduce performance (you won't be able to work out as long or as hard).
– Lower cancer risk. Several studies have found that people who drink five or more cups of water every day have half the risk of developing bladder or colon cancer of those who drink fewer than two cups a day.
– Reduced risk of kidney stones. At some point in their lives, 12-15% of Americans will form a kidney stone. Drinking a lot of liquid can reduce the risk by making sure that calcium, uric acid, and other substances are swept out of your system before they have a chance to crystalize into pain-inducing pebbles.
– A final note: Just about any fluid (yes, including milk, soda, and caffeinated drinks) can count toward your hydration goals. But in most cases, water is best, in part because it's cheap, widely available, and has no sugar or calories.
(Read Armin Brott's blog at www.DadSoup.com, follow him on Twitter, @mrdad, or send email to email@example.com.)