Chapter 12

Water Works

IN THIS CHAPTER

Understanding why you need water and how much you need

Explaining the nature and functions of electrolytes

Heeding the signs that you need more water

The human body is mostly water. The usual figure is 50 to 70 percent, but exactly how much water your own body contains depends on how much muscle and fat you have. Muscle tissue has more water than fat tissue, so, because the average male body has proportionately more muscle than the average female body, it also has more water. For the same reason (more muscle), a young body has more water than an older one.

You definitely won’t enjoy the experience, but if you have to, you can live without food for weeks at a time, obtaining subsistence levels of nutrients by digesting your own muscle and fat. But water’s different. Without it, you’ll die in a matter of days — more quickly in a place warm enough to make you perspire and lose water more quickly.

This chapter explains why water is so important and offers some pointers on how to keep your body’s water level level.

Investigating the Many Ways Your Body Uses Water

Water is a solvent. It dissolves other substances and carries nutrients and other material (such as blood cells) around the body, making it possible for every organ to do its job. You need water to

• Digest food, dissolving nutrients so they can pass through the intestinal cell walls into your bloodstream, and move food along through your intestinal tract
• Carry waste products out of your body
• Provide a medium in which biochemical reactions, such as metabolism (digesting food, producing energy, and building tissue), occur
• Send electrical messages between cells so your muscles can move, your eyes can see, your brain can think, and so on
• Regulate body temperature — cooling your body with moisture (perspiration) that evaporates on your skin
• Lubricate your moving parts

Maintaining the Right Amount of Water in Your Body

As much as three-quarters of the water in your body is in intracellular fluid, the liquid inside body cells. The rest is in extracellular fluid, which is all the other body liquids, such as

• Interstitial fluid (the fluid between cells)
• Blood plasma (the clear liquid in blood)
• Lymph (a clear, slightly yellow fluid collected from body tissues that flows through your lymph nodes and eventually into your blood vessels)
• Bodily secretions such as sweat, seminal fluid, and vaginal fluids
• Urine

A healthy body must have just the right amount of fluid inside and outside each cell, a situation described as fluid balance. Maintaining your fluid balance is essential to life. If there is too little water inside a cell, the cell shrivels and dies. If there’s too much water, the cell bursts.

The body maintains its fluid balance through the action of substances called electrolytes, mineral compounds that, when dissolved in water, become electrically charged particles called ions.

FLUORIDATED WATER: THE REAL TOOTH FAIRY

Except for the common cold, dental cavities are the most common human medical problem.

You get cavities from mutans streptococci, bacteria that live in dental plaque. The bacteria digest and ferment carbohydrate residue on your teeth (plain table sugar is the worst offender), leaving acid that eats away at the mineral surface of the tooth. This eating away is called decay. When the decay gets past the enamel to the softer pulp inside of the tooth, your tooth hurts. And you head for the dentist even though you hate it so much you’d almost rather put up with the pain. But almost doesn’t count, so off you go.

Brushing and flossing help prevent cavities by cleaning your teeth so that bacteria have less to feast on. Another way to reduce your susceptibility to cavities is to drink fluoridated water — water containing the mineral fluorine.

Fluoride — the form of fluorine found in food and water — combines with other minerals in teeth and makes the minerals less soluble (harder to dissolve). You get the most benefit by drinking water containing 1 part fluoride to every 1 million parts water (1 ppm) from the day you’re born until the day you get your last permanent tooth, usually around age 11 to 13.

Some drinking water, notably in the American Southwest, is fluoridated naturally when it flows through rocks containing fluorine. In fact, sometimes this water contains so much fluoride that it causes a brownish spotting (or mottling) while teeth are developing and accumulating minerals. This doesn’t happen with artificially fluoridated drinking water, which has only the approved 1 part fluoride to every 1 million parts of water.

By 2012, 67 percent of all Americans had access to adequately fluoridated public water supplies. Because fluorides are absorbed into bone, early on, some had feared that this might lead to an increased risk of cancer from fluoridated water. That has proved to be completely untrue. Today, the result of drinking fluoridated water has been an entirely healthful, lifelong 50 percent to 70 percent reduction in cavities.

Many minerals, including calcium, phosphorus, and magnesium, form compounds that dissolve into charged particles. But nutritionists generally use the term electrolyte to describe sodium, potassium, and chlorine. The most familiar electrolyte is the one found on every dinner table: sodium chloride — plain old table salt whose molecules dissolve in water into two ions: one sodium ion and one chloride ion. (For the non-chemists, an ion is an electrically charged atom.)

The electrolytes’ primary job

Under normal circumstances, the fluid inside your cells has more potassium than sodium and chloride. The fluid outside is just the opposite: more sodium and chloride than potassium. The cell wall is a semipermeable membrane; some things pass through, but others don’t. Water molecules and small mineral molecules flow through freely, unlike larger molecules such as proteins.

The process by which sodium flows out and potassium flows in to keep things on an even keel is called the sodium pump. If this process were to cease, sodium ions would build up inside your cells. Because sodium attracts water, if there is more than a normal amount of sodium inside the cell, extra water will flow in, eventually, bursting and killing the cell. Happily, the sodium pump, regular as a clock, prevents this, allowing you to move along, blissfully unaware of those efficient, electric ions that tell the water in your body where to go. (See the nearby sidebar “How does water know where to go?”)

HOW DOES WATER KNOW WHERE TO GO?

Osmosis is the process governing how water flows through a semipermeable membrane, such as the one surrounding a body cell. It allows water to flow through the membrane from the side where the liquid solution is least dense to the side where it is more dense, thus equalizing the density on both sides of the cellular wall.

You may ask, “How does the water know which side is more dense?” That one’s easy: Wherever the sodium content is higher, the fluid is more dense. When more sodium is present inside the cell, more water flows in to dilute it. When more sodium is in the fluid outside the cell, water flows out of the cell to dilute the liquid on the outside.

So when The Ancient Mariner complained, “Water, water everywhere, and not a drop to drink,” he wasn’t kidding. He was talking about the osmotic process that occurs if you drink seawater, causing liquid to flow out of your cells to dilute the denser salty liquid in your intestinal tract. The more seawater you drink, the more water you lose from your cells as you literally drink yourself into dehydration.

Of course, the same thing happens — though certainly to a lesser degree — when you eat salted pretzels or nuts. The salt in your mouth makes your saliva saltier, drawing liquid out of the cells in your cheeks and tongue, which feel uncomfortably dry. Solution: A glass of water.

Other tasks electrolytes perform

In addition to maintaining fluid balance, sodium, potassium, and chloride (the form of chlorine found in food) ions create electrical impulses that enable cells to send messages back and forth between themselves so you can think, see, move, and perform all the bioelectrical functions that you take for granted.

Sodium, potassium, and chloride are also major minerals (see Chapter 11) and essential nutrients. Like other nutrients, they’re useful in these bodily processes:

• Sodium helps your body digest proteins and carbohydrates and keeps your blood from becoming too acidic or too alkaline.
• Potassium is used in digestion to synthesize proteins and starch; it’s also a major constituent of muscle tissue.
• Chloride is a constituent of the hydrochloric acid (stomach acid) that breaks down food in your stomach. It’s also used by white blood cells to make hypochlorite, a natural antiseptic.

Getting the Water You Need

Because the body doesn’t store water, you need to take in a new supply every day, enough to replace what you lose when you breathe, perspire, urinate, and defecate. On average, this adds up to 1,500 to 3,000 milliliters (50 to 100 ounces, or 6 to 12.5 cups) a day. Here’s how:

• 850 to 1,200 milliliters (28 to 40 ounces) is lost in breath and perspiration.
• 600 to 1,600 milliliters (20 to 53 ounces) is lost in urine.
• 50 to 200 milliliters (1.6 to 6.6 ounces) is lost in feces.

Toss in some extra ounces for a safe margin, and you come up with the anecdotal eight 8- or 10-ounce glasses of water a day. But, in fact, not all the water your body requires has to come from plain water.

For starters, about 15 percent of the water that you need is created when you digest and metabolize food, producing carbon dioxide (a waste product that you breathe out of your body) and water composed of hydrogen from food and oxygen from the air that you breathe. The rest of your daily water comes directly from what you eat and drink.

Next, as nutritionists know, some of the water you require is right there in your food. Fruits and vegetables are full of water. Lettuce, for example, is 90 percent water. Even foods that you’d never think of as water sources provide water, including hamburger (more than 50 percent), cheese (the softer the cheese, the higher the water content — Swiss cheese is 38 percent water; skim milk ricotta, 74 percent), a plain, hard bagel (29 percent water), milk powder (2 percent), and butter and margarine (10 percent). In fact, the only foods with no water are pure oils.

In 2008, the National Institutes of Health bypassed the eight-glass rule, saying that women get enough water from about 91 ounces (2.7 liters) of water a day from all sources; men, about 125 ounces (3.7 liters) a day. And the usual qualifier holds: Everybody is individual, so these are only guidelines.

Not all liquids are equally liquefying. The caffeine in coffee and tea and the alcohol in beer, wine, and spirits are diuretics, chemicals that make you urinate more copiously. Although caffeinated and alcohol beverages provide water, they also increase its elimination from your body — which is why you feel thirsty the morning after you’ve had a glass or two of wine.

In other words, a healthy adult in a temperate climate who isn’t perspiring heavily can get enough water simply by drinking only when he or she is thirsty.

BAD NEWS BOTTLES

Most people in the United States get their drinking water straight from the tap, but a steadily growing number of Americans get theirs in plastic bottles.

Exactly how many people buy exactly how many bottles of water may vary a bit from source to source, but according to the Beverage Marketing Corporation, consultants to the beverage industry, by 2014, Americans were downing 11 billion gallons of bottled water a year, up from about 4.7 billion in 2000. That number translates to nearly 34 gallons of bottled water per year for every man, woman, and child in the country.

Those gallons don’t come cheap. The National Resource Defense Council estimates that bottled water costs anywhere from 240 to 10,000 (!) times as much as safe tap water. They’re also expensive for the environment. According to the Environmental Protection Agency, in 2008, Americans tossed away 2.48 million tons of plastic bottles and jars to live forever in landfills or make their way out to sea. Worldwide, the United Nations estimates that every single square mile of ocean on the planet contains 48,000 pieces of floating plastic.

Container recycling laws, local bans on bottled water, and newly reusable bottles offer hope of some relief from the tons of plastic garbage. So does new technology suggesting that ultraviolet light and heat may render plastic bottles degradable.

Until then, the better bet is to buy a light-weight thermos and carry tap water. Your wallet and your planet will thank you.

Evaluating Electrolytes

The electrolytes sodium, potassium, and chlorine are chemicals that dissolve in water, separating into atoms called ions that conduct electricity. In your body, electrolytes enable the transfer of messages back and forth between cells so keeping them balanced is essential to maintaining the normal function of your organs, tissues, and cells.

Sodium

The Centers for Disease Control (CDC) estimated that most American adults consume an average 3,400 milligrams (about 1.5 teaspoons) of sodium a day. But the AI (Adequate Intake; more about that in Chapter 3) of sodium for healthy adults age 18 to 50 is 1,500 milligrams (about 2/3 teaspoons) a day; the recommended intake for older adults is 100 to 200 milligrams less. These are levels of consumption many experts such as the American Heart Association consider protective against hypertension (high blood pressure) and other forms of heart disease.

Certainly, people who are sensitive to sodium or have certain medical conditions, such as diabetes, may indeed end up with high blood pressure that can be lowered if they reduce their sodium intake. For more about high blood pressure, check out High Blood Pressure For Dummies, by Alan L. Rubin, MD (Wiley).

The question is whether extra sodium is hazardous to everyone. The answer is, maybe not. Like several vitamins, electrolytes dissolve in water, so they’re excreted in urine. The amount of electrolytes you put out in your urine is a measure of how much sodium, potassium, and chloride you consumed in food and beverages. The more you take in, the more you put out.

This simple formula proved useful in August 2014, when a team of scientists published a report in the New England Journal of Medicine based on data from a Prospective Urban Rural Epidemiology (PURE) survey of more than 100,000 people. Their analysis showed that people at both ends of the excretion spectrum — very low levels and very high levels — had a higher risk of death and cardiovascular disease than those in the middle. Naturally, this has led to many interesting discussions among nutritionists and other experts; the end result is not yet in sight.

Potassium and chloride

Potassium and chloride are found in so many foods that here, too, a dietary deficiency is a rarity. In fact, the only recorded case of chloride deficiency was among infants given a formula liquid from which the chloride was inadvertently omitted. Currently, the AI for potassium and chloride were set at 4,700 milligrams (4.7 grams) for potassium and 2,300 milligrams (2.3 grams) for chloride.

When you need more

Most Americans get plenty of water and the electrolytes as a matter of course, but sometimes you actually need extra, such as in the following instances.

When you’re sick to your stomach

Repeated vomiting or diarrhea drains your body of water and electrolytes. Similarly, you also need extra water to replace the liquid lost in perspiration when you have a high fever.

When you lose enough water to be dangerously dehydrated, you also lose the electrolytes you need to maintain fluid balance, regulate body temperature, and trigger dozens of biochemical reactions. Plain water doesn’t replace those electrolytes. Check with your doctor for a drink that will hydrate your body without upsetting your tummy.

WHEN PLAIN WATER IS TOO PLAIN

Serious dehydration calls for serious medicine, such as the World Health Organization’s electrolyte replacement formula:

• 6 level teaspoons sugar
• 0.5 teaspoon salt
• 1 quart fluid (approx. 1 liter)

The best fluid is plain, clean water. In an emergency — or in a place where the water is less than perfectly safe — the formula allows substitutes, such as freshly poured coconut water or clear consommé or unsweetened weak tea or fruit juice. If only questionable water is available, boil it.

Warning: If you’re reading this while lying in bed exhausted by some variety of turista — the traveler’s diarrhea acquired from impure drinking water — don’t make the formula without absolutely clean glasses, washed in bottled water. Better yet, get paper cups.

When you’re exercising or working hard in a hot environment

When you’re warm, your body perspires. The moisture evaporates and cools your skin so that blood circulating up from the center of your body to the surface is cooled. The cooled blood returns to the center of your body, lowering the temperature (your core temperature) there, too.

If you don’t cool your body down, you continue losing water. If you don’t replace the lost water, things can get dicey because not only are you losing water, but you’re also losing electrolytes. The most common cause of temporary sodium, potassium, and chloride depletion is heavy, uncontrolled perspiration.

Deprived of water and electrolytes, your muscles cramp, you’re dizzy and weak, and perspiration, now uncontrolled, no longer cools you. Your core body temperature begins rising, and without relief — air conditioning or a cool shower, plus water, ginger ale, or fruit juice — you may progress from heat cramps to heat exhaustion to heat stroke. The latter is potentially fatal.

When you’re on a high-protein diet

You need extra water to eliminate the nitrogen compounds in protein. This is true of infants on high-protein formulas and adults on high-protein weight-reducing diets. See Chapter 6 to find out why too much protein may be so harmful.

When you’re taking certain medications

Because some medications interact with water and electrolytes, always ask whether you need extra water and electrolytes whenever your doctor prescribes the following:

• Diuretics: These drugs increase the loss of sodium, potassium, and chloride.
• Neomycin (an antibiotic): This medicine binds sodium into insoluble compounds, making it less available to your body.
• Colchicine (an antigout drug): This medicine lowers your body’s absorption of sodium.

Dehydration: When the Body Doesn’t Get Enough Water

Every day, you lose an amount of water equal to about 4 percent of your total weight. If you don’t take in enough water to replace it, warning signals go off loud and clear.

First signs

Early on, when you’ve lost just a little water, equal to about 1 percent of your body weight, you feel thirsty. If you ignore thirst, it grows more intense.

When water loss rises to about 2 percent of your weight, your appetite fades. Your circulation slows as water seeps out of blood cells and blood plasma. And you experience a sense of emotional discomfort, a perception that things are, well, not right.

Worsening problems

By the time your water loss equals 4 percent of your body weight (5 pounds for a 130-pound woman; 7 pounds for a 170-pound man), you’re slightly nauseated, your skin is flushed, and you’re very, very tired. With less water circulating through your tissues, your hands and feet tingle, your head aches, your temperature rises, you breathe more quickly, and your pulse quickens.

Really bad trouble

After this, things go downhill more quickly. When your water loss reaches 10 percent of your body weight, your tongue swells, your kidneys start to fail, and you’re so dizzy that you can’t stand on one foot with your eyes closed. In fact, you probably can’t even try: Your muscles are in spasm.

When you lose enough water to equal 15 percent of your body weight, you’re deaf and pretty much unable to see out of eyes that are sunken and covered with stiffened lids. Your skin has shrunk, and your tongue has shriveled.

The crash

When you’ve lost water equal to 20 percent of your body weight, your body is at the limit of its endurance. Deprived of life-giving liquid, your skin cracks, and your organs grind to a halt. And so do you.

Ave atque vale, or as the Romans say when in the United States, Canada, Great Britain, Australia, or any place where English is the mother tongue: “Hail and Farewell.”

WATER WORDS

Chemically speaking, H₂O (one molecule hydrogen, two molecules oxygen) is a queer duck, the only substance on earth that exists as a liquid (water) and a solid (ice) — but never as a bendable plastic material. No, as chemistry teachers explain each year to first-year chemistry students, snow is not plastic water. It’s a collection of solids (ice crystals). Semantically speaking, water is also challenging. For starters, water may be hard or soft, but these terms have nothing to do with how the water feels on your hand. They describe the liquid’s mineral content:

• Hard water has lots of minerals, particularly calcium and magnesium. This water rises to the Earth’s surface from underground springs, picking up calcium carbonate as it moves up through the ground.
• Soft water has fewer minerals. In nature, soft water is surface water, the runoff from rain-swollen streams or rainwater that falls directly into reservoirs. Water softeners are products that attract and remove the minerals in water.

What you get at the supermarket is another list of water words:

• Distilled water is tap water that has been distilled, or boiled until it turns to steam, which is then collected and condensed back into a liquid free of impurities, chemicals, and minerals. The term distilled is also used to describe a liquid produced by ultrafiltration, a process that removes everything from the water except water molecules. Distilled water makes clean, clear ice cubes and serves as a flavor-free mixer or base for tea and coffee. It won’t clog a steam iron, and it’s valuable for chemical and pharmaceutical processing.
• Spring water is water from springs relatively near the Earth’s surface. This water has fewer mineral particles and what some people describe as a “cleaner taste” than mineral water.
• Mineral water is water from deeper down; it picks up minerals on its journey upwards. Mineral spring water is naturally alkaline, which makes it a natural antacid and a mild diuretic.
• Still water is spring water that flows up to the surface on its own. Sparkling water is pushed to the top by naturally occurring gases in the underground spring. So, you ask, what’s the big difference? Sparkling water has bubbles; still water doesn’t.
• Springlike or spring fresh are terms designed to make the water in the bottle seem more prestigious. Products labeled with these terms aren’t spring water; they’re most likely to be filtered tap water, the liquid that flows out when you turn on the faucet (see distilled water, earlier in this list).