The intense summer heat brings thirst, dry throats and loss of energy. Water resolves all these problems and, for the health-conscious, does not have any calories. Luckily, there are many more kinds of water to choose from nowadays than just tap and carbonated bottled water.

Alternatives include natural artesian water from Fiji, spring water from Norway, water that is flavored or has added minerals, ready-to-drink fruit spritzers, energy drinks and old-fashioned green tea.

Take your pick; it really doesn't matter. There is only one golden rule this summer: Drink plenty of it! After all, water is not only a trendy lifestyle product. It is also, and most importantly, the main ingredient of life.

Every day we ingest a liter or more liquid via food, for example, by eating watery fruits and vegetables like melons and tomatoes. The German Nutrition Society (DGE), based in Bonn, recommends intaking at least an extra 1.5 liters in the form of liquids. "When temperatures exceed 35 C, you'd also do well to drink double that amount," says DGE spokeswoman Antje Gahl.

She stresses that even athletes should increase their water intake in summer: A glass of water or apple spritzer a half or quarter-hour before the athletic activity is generally sufficient.

But during activities that last longer than an hour, such as running, she recommends drinking a half-glass or glass "in small swallows" every 15 minutes, even when temperatures are normal.

Another useful tip is not to wait until you're thirsty before having a drink, and this is especially true for older people. With advancing age, the sensation of thirst diminishes, says Wolfgang Wesiack, president of the Wiesbaden-based Association of German Internists (BDI).

The risk of dehydration is especially high in summer because perspiration causes the body to lose more liquid. If the lost liquid is not replenished, the blood can thicken. This reduces the body's ability to function and can lead to confusion and even loss of consciousness or kidney failure.

"The best time to drink water is between meals," advises Barbara Hendel of Munich, a holistic medical doctor and author of the book Water and Salt, Wellspring of Life. The ideal time would be about 15 minutes before a meal or an hour or two afterwards.

"You can also drink water during meals, of course, but too much dilutes the digestive juices and delays or hampers digestion," she says.

The kind of liquid you drink is also important. Although coffee and alcohol consist largely of water, Hendel says, "They also contain other substances, so the water has fewer free docking places to bind toxic substances and excrete them." High-proof spirits even take water from the body.

Wesiack recommends natural mineral water because it contains salts that the body loses through perspiration, but the most popular mineral water is still the carbonated kind, with medium-fizzy varieties not far behind.

Non-carbonated and slightly flavored waters are also enjoying increasing popularity, but Wesiack sees no physical benefits in the latter. He says that lifestyle products with, say, strawberry flavors are "not medically indicated", in other words, unnecessary.

Soft drinks are unsuitable thirst quenchers because of their high sugar content, which makes you thirstier, the DGE notes. It says that herbal or fruit teas, fruit spritzers and low-calorie refreshing drinks are better.

The DGE's Gahl suggests a simpler and cheaper alternative: tap water! Foreigners should note, however, that the DGE was targeting German consumers, and they would do well to stick to the bottled version while in China.

(China Daily July 18,2008)