If your shot at good health is a daily glass of fresh fruit juice, it might be time to change that habit.

The Health Promotion Board (HPB) says that a glass of juice is not as healthy as you think, because it contains as much sugar as a sweetened drink.

HPB chief executive officer Zee Yoong Kang said: "Many people think juices are good for health and, yes, there are nutrients, but they should limit their intake to one glass a day."

Dr Annie Ling, director of HPB's Obesity Prevention Division, said: "In fact, fruit juices generally contain much higher sugar levels than sweetened drinks." She added that sugar levels in fruit juices vary, with higher sugar levels in more acidic fruit like apples and berries.

Freshly squeezed juice contains 10 to 20 per cent less sugar than packaged drinks, which are reconstituted from concentrates.

Said Dr Ling: "We apply the same allowance for sugar sweetened drinks to fruit juices - no more than one glass a day."

Singaporeans take an average of 11 teaspoons of sugar a day, with the top fifth hitting 18 teaspoons a day, HPB figures show.

The World Health Organisation (WHO) recommends no more than 10 teaspoons of "free sugar" daily, or sugar added to foods by the manufacturer and those naturally present in honey, syrups and fruit juices. One in three people here takes more than that.

Professor Jim Mann, of the WHO Nutrition Guidance Expert Advisory Group, said this does not include sugars in whole fruit and vegetables which digest more slowly and take longer to enter the blood stream. So eating the fruit is far better than drinking it as it gives you the nutrients without the sugar rush.

Mr Zee said that two-thirds of sugar consumed here come from drinks, including fruit juices.

This much sugar is detrimental to health and one reason for the ballooning obesity rate, he said, with the bulk of sugar coming as "empty calories" in drinks. This is because highly refined carbohydrates wear out the insulin-producing part of the pancreas. Also, Dr Ling explained: "Insulin causes fat cells to go into storage overdrive leading to weight gain."

Even the supposedly healthy yoghurt drinks have about five teaspoons of sugar in a 200g portion - or just two spoons less than a 330g carbonated drink.

Mr Zee hopes to reduce consumption of sugar here over time by persuading people to learn to enjoy less sweet drinks. He dismissed calls for a health tax on white sugar, which he says will not work as people will simply switch from one unhealthy food to another. Furthermore, such a tax will hit the poor hard. Instead, he wants to change their palate.

People in Japan and Hong Kong take their drinks with less sugar than Singaporeans. Even jasmine tea, which is drunk with no sugar in Japan and 21/2 teaspoons of sugar in Hong Kong, has four teaspoons of sugar when sold here.

Dr Ling said the "growing level of sugar consumption over the years" is a concern. According to HPB figures, people here have increased their sugar consumption by 10 per cent from 2009 to 2012.

This month's WHO Bulletin says recent "rigorous" and "scientific" evaluation reinforces the 2003 recommendation to reduce sugar intake. Prof Mann said there is an enormous body of evidence that reducing sugar consumption "is almost certain to halt the epidemic of obesity and to reduce the risk of type 2 diabetes and other related non-communicable diseases". This includes breast and colorectal cancers and cardiovascular disease.

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