"You really should drink more water" - a well intended but mildly irritating piece of advice delivered to each one of us from time to time. Around 60 percent of the body is made up of fluid, making it more vital than food for our nutrition. Hunger strikers have survived for 60-70 days without a bite, but deprived of water (and salt) this would be less than a week.

Two liters or 8x240ml cups are the standard recommended amounts for the adult population. This is a useful, but highly generalized figure and precise calculations depend on age, weight and body temperature. Allowing 35ml fluid per kg body weight for those between 18-60 years (30ml for those over 60 years) gives a more accurate figure in addition to replacing excess losses through sweating, respiration, diarrhea etc. Also try to ensure your urine remains pale yellow to colorless throughout the day.

I'm probably not helping my reputation as a dietitian by confessing that I find plain water a little tedious - adding a slice of lemon or icing in the freezer certainly makes it more palatable, and cold drinks are absorbed more quickly through the stomach.

Contrary to popular belief, tea and coffee do count. Avoid relying on these as they have a mildly diuretic effect - especially if you are unaccustomed to caffeinated drinks. Green tea is lower in caffeine, and there are a huge variety of caffeine-free herbal, flower and fruit teas available here. The Chinese habit of carrying around a flask of cold tea is certainly a good idea.

Fruit juice is another option but limit to 1-2 cups per day - it is rich in vitamin C but contains large amounts of natural sugar and citric acid. Diluting juice is advisable and especially important with children to protect their teeth.

Also full of sugar, soda is calorific and certainly detrimental to dental health. Reduced sugar squash drinks are a good option, although I have yet to find them in Beijing. A glass of milk or soy milk each day will help with both fluid and calcium intake.

Choosing fluid-dense food options also helps. Soups and broths are, of course, primarily liquid, and in the hot weather you can experiment with cold soups such as Gazpacho, Vichyssoise and chilled cucumber soup. Include a crisp salad with main courses - cucumbers, tomatoes and radishes are particularly good.

For a fluid-filled dessert, try granitas, sorbets and jellies. For a real thirst quencher, indulge in a towering shaved ice dessert at Bellagios. Fruit is a brilliant option, and snacking on any type will really help with meeting the milliliters. The so-named watermelon contains 96 percent water, making it an especially good choice.

Dehydration can be a potentially lethal condition especially when accompanied by vomiting and diarrhea. Fluid, sodium, and other electrolytes may need to be replaced in hospital with intravenous fluids. Early signs of dehydration include low urine output, increased thirst, dry mouth and decreased blood pressure. Conversely it is possible to drink too much water leading to water intoxication whereby levels of salt and other electrolytes become too diluted. Earlier this year in California, a woman died following a water-drinking radio contest in which she consumed 7.5 liters in a very short period of time.

This nutrition-related column is written by Nina Lenton, a qualified dietitian living in Beijing and working at Bayley and Jackson Medical Center. Contact her at nina.lenton@bjhealthcare.com.

(China Daily 07/19/2007 page14)