Thu, May 01, 2008
Mind Your Body, The Straits Times
Drink to your health
SINGAPORE: Ask the question 'How much water should I drink?' and the typical answer is eight glasses daily.
But now, it seems this 'gold standard', that we've all grown up with, is without scientific proof.
Earlier this month, two scientists at the University of Pennsylvania found no evidence that downing eight glasses of water a day is good for our health.
WATER WORKS
TAP WATER: Drawn from four sources, namely water from local catchment areas, imported water from Johor, Newater and desalinated water.
Why it's good: Contains minerals such as calcium, chloride, magnesium, potassium and sodium and trace amounts of iron and manganese. Calcium benefits the bones while magnesium is good for the heart. Singapore boasts one of the world's lowest DMFT (decayed, missing and filled teeth) index for 12-year-olds, thanks to the fluoride in our tap water which has been added since 1957.
MINERAL OR SPRING WATER: Drinkable water that is drawn from an underground source and contains dissolved mineral salts such as calcium, iron and magnesium.
Why it's good: Such water usually tastes pure and clean, with little aftertaste. Often touted as possessing health-giving properties, its low mineral content means it is also suitable for babies.
Examples: Evian Mineral Water (right, 500ml, $1.60, from Isetan Supermarket) and Voda Voda Spring Mineral Water (500ml, $1.27).
SPORTS OR FITNESS WATER: Drinkable water that has undergone further purification and is scientifically formulated. It also often contains carbohydrate, electrolytes or sodium and is usually enhanced with B vitamins to help in energy metabolism.
Why it's good: Ms Png Weileen, head of sports nutrition at Singapore Sports Council, said the intake of carbohydrate and fluid has been shown to be beneficial for high intensity exercise of about 60 minutes.
Examples: Pocari Sports Water (500ml, $1.25, from Isetan Supermarket), Gatorade Rain-Berry Sport Drink (right, 591ml, $1.95).
SPARKLING WATER: Carbon dioxide is added to mineral or spring water to make it fizzy.
Why it's good: Ms Jaclyn Reutens, a dietitian at Aptima Nutrition and Sports Consultants, said that bottled water is convenient and some individuals find that bottled water tastes better than tap water.
Examples: San Benedetto Sparkling Mineral Water (1.5l, $2), Perrier Natural Sparkling Water (right, 750ml, $2.75).
DISTILLED WATER: Purified by boiling tap water and condensing the steam. It usually contains few minerals.
Why it's good: For those who don't like the taste of tap water, this is a good alternative as it is mostly tasteless.
Examples: Ice Mountain Pure Drinking Water (right, 600ml, 45 cents), FairPrice Pure Drinking Water (500ml, 36 cents).
VITAMINISED WATER: Drinkable water which contains added vitamins.
Why it's good: While vitamins are always good for you, Health Promotion Board nutritionist Benjamin Lee cautioned: 'Most vitamins added to water are water-soluble and are likely to pass out of the body quickly. However, if you were to drink many bottles of water with added vitamins, there is a chance that you might get diarrhoea.'
Consuming too much of some vitamins, like more than 3,000mg of vitamin C a day, is known to cause diarrhoea. To be safe, make sure that the vitamin C content of all the water with added vitamins you drink a day is less than 1,000mg, he added.
All items from NTUC FairPrice unless otherwise credited.
Dr Dan Negoianu and Dr Stanley Goldfarb reviewed medical literature dating back to the early 1970s and found that there were no scientifically proven health benefits to gulping so much water a day.
Apart from athletes and people living in hot, dry climates, the average healthy person does not need to drink eight glasses of water daily, they said.
Their findings, published in the Journal Of The American Society Of Nephrology on April 2, got the nod from some dietitians and doctors here.
Dr Stanley Liew, consultant endocrinologist at Raffles Hospital, said: 'Our bodies can adapt to our environment and water availability. We can rely on our thirst sensation to guide us in our water consumption. There is no need to force ourselves to drink eight glasses of water daily.'
Changi General Hospital's senior consultant sports physician and head of Changi Sports Medicine Centre Dr Ben Tan said: 'In practice, the amount depends on how much water we lose through expired air and sweat. As long as we produce relatively clear urine a few times a day, we should be fine.'
But others, like nutritionist Benjamin Lee from the Health Promotion Board, maintain that you should consume between six and eight glasses of fluid daily, including soup or porridge broth.
The body uses between one and 11/2 litres of water every day on average and more in high temperatures or when you are exercising. That's why you need water.
The human body is 70 per cent water and there is water in its circulatory system, interstitial space - spaces between the cells - and within the cells, said Dr Tan.
The electrolytes and enzymes that are in solution in the body need to be kept within a tight concentration range in order for it to function properly, he added.
Water is a major component of blood, which is in charge of supplying oxygen and nutrients to the organs. Water also assists daily bodily functions like regulating body temperature and lubricating joints for ease of movement.
Dr Liew added: 'Our kidneys rely on huge amounts of water being filtered daily to excrete toxic substances from our bodies. Deprived of water, we can survive only for days.'
A person can generally survive without water for a period of between two and seven days.
But while drinking too little water will cause dehydration, resulting in conditions like a dry mouth and darkening of urine, drinking too much can also damage one's internal system.
Water intoxication, or hyponatremia, occurs when too much water is drunk within a short space of time. This situation can cause an imbalance of the body's electrolytes, disrupting normal brain function, which can lead to swelling in the brain and death.
In contrast, severe dehydration means that the body does not have enough water to carry out its normal functions and this can cause kidney failure and even death.
Moderation is the key. After all, the more water you drink, the more is passed out as urine.
Dr Lew Kian Hwa, registrar at Alexandra Hospital's Health For Life Centre, said: 'The normal amount of urine one generates is between 800 and 2,200ml per day. It varies with your intake of water and the normal frequency of urinating which is about six to eight times per day.'
While the experts are divided over how much water one should drink, they all dismiss the notion that bottled water is healthier than tap water.
Last year, Singapore imported 154.5 million bottles of drinking water, 32 million more than in 2006. According to the Public Utilities Board (PUB), Singapore requires 300 million gallons of water a day.
Mrs Magdalin Cheong, chief dietitian and senior manager at Changi General Hospital's dietetic and food services, said: 'Water is water, tap or otherwise. As for the added nutrients in bottled water, do we need them? One's intake of vitamins and minerals should be from one's diet, not just from drinking water.'
Ms Jaclyn Reutens, a dietitian at Aptima Nutrition and Sports Consultants, said: 'The amount of minerals or fruit added in bottled water is not a significant source of nutrients.'
A PUB spokesman said that more than 80,000 tests on water quality are conducted on Singapore's water every month and Singapore's tap water exceeds the requirement of the World Health Organisation (WHO) Drinking Water Guidelines.
Dr Tan summed up the argument for sensible drinking: 'Common sense should prevail.'
This article was first published in Mind Your Body, The Straits Times, on Apr 30, 2008.
