Bread may be the staff of life, but water is the fountain of life. Here, the Swiss Association for Nutrition gives practical advice about what the body needs in the way of fluids, and how these can be satisfied - by water, and by non-alcoholic drinks.

Water requirements

Water comprises 60% of the body weight in men, 50% in women, and up to 80% in the newborn. Thus there are 48 kg (105 lb) of water in an 80 kg (175 lb) man. Every cell of the human body contains water, and when all the different fluids are combined - blood, lymph, urine, and bodily secretions (i.e. tears, saliva, digestive juices, nasal secretions, perspiration) - the water component is very substantial. Water has a wide variety of functions. It helps supply nutrients, enzymes, and hormones to the cells, and is essential for removal of wastes. It supplies tissues and skin with fluids and helps regulates body temperature. It facilitates digestion and elimination by adding volume and by fecal hydration.

Water volume remains constant when there is a physiological equilibrium. Water intake averages about 2650 mL (90 ounces) over 24 hours in adults, but varying, of course, between individuals. ¹ This intake includes external intake (875 mL from solid nutrients and 1440 mL from oral fluids) and internal production (335 mL water derived from oxidation or metabolism of nutrients). Water excretion likewise equals 2,650 mL over 24 hours. We lose 160 mL in the feces, 500 mL expired from the lungs, and 550 mL through the skin. The other 1,440 mL (50 ounces) is excreted in the urine.

In certain conditions the need for fluids increases sharply, such as at high temperatures, with bodily exercise, in dry cold environments, with increased salt consumption, and in cases of illness (fever, diarrhea, vomiting). Symptoms appear when we lose only 1% of our body weight in the form of water: headache, decreased mental ability, loss of concentration, decreased athletic performance, and thirst. Thirst is a recognized sign of dehydration. Any loss of fluids must be obviously be compensated by increased fluid intake.

How much must one drink?

To have a fluid intake of 2.5 liters per day, it's advisable to drink 1.5 liters (50 ounces) of liquids; the remainder will be provided by eating. About one-third of the water we consume comes from solid foods since their fluid content is often surprisingly high. At the top are vegetables (95% water) and fruit (80-95% water), but other foods also have a substantial amount of water, such as meat and fish (65-70%), bread (35%), and grains (12%). Only sugar and oil are completely water-free.

What should one drink?

The range of available beverages has increased significantly in recent years, but in most cases they don't qualify as primary beverages because of their composition. Fluid intake during the day, at meals, and to quench thirst should be supplied primarily through water.

The beverage groups: the base of the nutrient pyramid!

From a physiological view, the function of a drink is to hydrate the body. Although water is the only liquid that is essential for life, a variety of motivations drive us to consume other drinks. First there is the immediate satisfaction of the senses through the smell, taste, and temperature of the liquid being consumed, and then the satisfaction that results from feeling good (quenched thirst or renewed energy). Its social function is also a reason for drinking - offering coffee or tea to a visitor is a sign of hospitality and appreciation.

Water
Tap water or mineral water: Water is denigrated as "tasteless," it's not a "social lubricant", and it's even reminiscent of punishment ("... on bread and water"). This negative image is unjustified, because water is the only essential and recommendable drink for meeting our fluid requirements. In Switzerland, tap water is completely safe from a bacteriological viewpoint, while its mineral content varies by region. If we don't like the taste, we can flavor the water in several ways: using plant or fruit additives (lime blossom, peppermint, verbena, orange blossom), spiced tea, or bouillon.

Bottled Water: non-sparkling ('still') or sparkling mineral water has a widely varying mineral content depending on type. Differences are found especially in the amount of sodium, calcium, magnesium, iron, fluoride, sulfate, or even carbon dioxide in the water. Descriptive information is supplied on bottle labels, allowing quick comparison of mineral percentages (see Table below).

• Drink tap or mineral water whenever you want.
• An appropriate mineral water can effectively satisfy a particular need, such as a higher daily dose of calcium. Consumption of heavily salted water, on the other hand, is not recommended.
• The unpleasant taste of residual chlorine in city water will dissipate after a while if the water is left in an uncovered container, because of chlorine's volatility.
• A few drops of lemon juice or a piece of citrus peel are all it takes to give a pleasant taste to tap water or a brewed drink.
• Unsweetened fruit teas or spiced teas are recommended drinks, provided no sugar or very little sugar is added.

Fruit and Vegetable Juices
Fruit juices consist of 100% fresh fruit juice which, with the exception of additives, retains it full nutritional value - vitamin C, minerals (calcium, magnesium, phosphorus), fructose (= fruit sugar) and trace elements. Their sugar content is high - between 5% and 20% by weight.

Fruit nectar is made of 25-50% fresh fruit juice or fruit pulp, enriched with saccharose and other sugars. Fruit and vegetable juices are considered foods. They can contribute just as much to a balanced diet as the fruits and vegetables from which they are derived.

• However, they cannot be considered primary beverages because of their sugar content, even though they have a naturally high nutritional value. Anyone drinking large quantities of these beverages is ingesting too much sugar. We recommend an intake of two to three fruits per day, or an equivalent of 0.15 liters of fruit juice as a substitute for one fruit.
• The sugar content of fruit juices can be diluted with water.

Fruit Juice Drinks (Sweetened Fruit Drinks)
Beverages enriched with fruit juice must contain at least 10% of the specified juice. They are made by diluting fruit juice, fruit syrup or fruit concentrate with water and adding sugar.

• They are much less valuable than as fruit juices; from the perspective of their nutrients, they are more like soft drinks with fruit juice.

Soft Drinks
Soft drinks with fruit juice contain 4-10% fruit juice, soft drinks with fruit or plant flavor 0-4%. These "sodas" are carbonated by adding carbon dioxide.

Colas - that is, sodas with caffeine - also belong to this category, as well as tonic water, to which quinine is added for the purpose of giving a slightly bitter taste. The most common feature of these beverages is their sugar content, which ranges between 100 and 120 g per liter, that is, 25-30 spoons of sugar! These flavored beverages contain very few vitamins or minerals. From a nutritional perspective, their value is therefore completely negligible.

• Drinking too many liquids in the form of sweetened beverages can cause nutritional imbalance, and such beverages should therefore be used moderately.

Syrup
Syrup has the commercial advantage of being easy to store and use. Fruit syrup contains only 30% fruit juice, however, and a syrup with fruit flavor none at all! From a nutritional perspective, it is therefore the same as the other sweetened beverages: rich in sugar and poor in nutrients.

• It is advisable to limit consumption of syrup because of its sugar content.

'Light' Beverages
Practically all beverages (nectar, soda, syrup...) are available in a light form, which contains less sugar than their original. Instead of sugar, highly concentrated sweeteners (saccharine, aspartame) or other types of sugar with a stronger sweetening effect (e.g., Sorbitol) may be used. A liter of beverage sweetened in this way corresponds to an energy supply of between 10 and 100 kcal.

• Light beverages may be an alternative to sugared products. However, the danger is that one may become used to the sweet taste and not want to give it up.
• They are particularly useful to limit intake of sugar and calories in people who are overweight or have diabetes.
• Excessive consumption of these beverages can cause problems (e.g., diarrhea), especially in children. It's therefore advisable not to drink more than 1-2 glasses a day.

Stimulant Beverages
Coffee and tea are distinctive because of their caffeine content. They should only be consumed in small quantities because they are stimulants.

• Coffee substitutes from grains or caffeine-free coffee are good alternatives.
• Since caffeine-containing coffee has a diuretic effect, a glass of water should be drunk after every cup of coffee.
• Heavy drinkers of coffee or tea must watch their consumption of added sugar or cream.

"Energy drinks" , so called because of their composition, should be considered soft drinks to which caffeine or guar gum are added. They are touted as beverages that promote well-being and vitality.

• These energy drinks (also called isotonic drinks) are not miracle drinks and should be consumed in moderation, and never in association with alcohol.

Alcopops or Premix are energy drinks with alcohol added (5%).

Milk and Milk Beverages
Milk, drinking yogurt, whey, and milk serum are considered foods. They are rich in minerals (calcium, phosphorus) and in vitamins A, D, and B. These beverages contribute to a well-balanced diet just as much as solid foods in the milk product category.

• These beverages with high natural nutritional value cannot be considered primary beverages. We recommend consumption of two to three milk products per day, and any one of these may be substituted by 200 mL milk.

The market also offers soft drinks made of milk or its derivatives . Milk, whey, or milk serum are diluted with water and enriched with sugar, fruit juice, or plant extracts.

• These beverages do not have the same nutritional value as milk. Because of their composition, they fall instead into the category of soft drinks. They should be consumed in small quantities.

Please note

• Only water is essential for life.
• Drink at least 1.5 liters per day - i.e., about 8 large glasses.
• Keeping a diary over several days helps you get used to drinking more.
• Since 1/3 of fluid intake comes from solid foods, people who don't eat very much (especially few fruits or vegetables) must drink more.
• Only small quantities of sugar-containing beverages should be consumed, and only as a substitute.
• Fluid nutrients such as milk und fruit juice may be substituted for solid foods of the same category.

Mineral content of different mineral waters

Source

Schweizerische Vereinigung für Ernährung / The Swiss Association for Nutrition (SAN). Merkblätter zur Ernährung, Vol. II. Main Editor: Herr Hansjörg Ryser, Bern.Website at: http://www.sve.org/english/index.html

Links

• Make Water Your Fountain of Life
• Study Shows Coffee Not Hazardous to Heart Health

Footnotes

1. 100 mL = 3.3 fluid ounces