Is fruit juice bad for your health?

It sounds like a crazy question, but fruit juice could be worse for you than fizzy drinks.

Juice exudes health and vitality. It is officially one of your 'five-a-day'. It's what they sell in juice bars, those yogafied temples of wheatgrass.

But fruit juice is also, according to the American obesity expert Robert Lustig, basically just sugar and is therefore, in his view, a 'poison'. Lustig is the author of Fat Chance: The Bitter Truth about Sugar (4th Estate, £13.99), published earlier this year. He sees sugar as the major culprit in the obesity crisis. Not so surprising, except for his shock revelation that the worst sugars may be those that appear the healthiest. 'Calorie for calorie, 100 per cent orange juice is worse for you' than sugary sodas, Lustig says.

This sounds alarmist, until you read some of the case studies from Lustig's childhood obesity clinic in San Francisco. One eight-year-old already has high blood pressure, thanks to a three-glasses-a-day juice habit. A six-year-old Latino boy comes to the clinic weighing 100lb, 'wider than he is tall'. His mother, a poor farm worker, has been letting him drink a gallon of juice a day because a government welfare programme gives them the juice for free.

Obviously, most of us drink nothing like a gallon of juice a day. But our juice portions are still out of whack. Over the past 30 years consumption of fructose – the sugar in juice – has more than doubled. Juice didn't used to be seen as something with which you quenched your thirst; it was more like a vitamin shot, a tiny dose of goodness. A book from the 1920s on feeding children by L Emmett Holt says that you should give toddlers just one to four tablespoons (15-60ml) of fresh orange or peach juice. Compare this with today's 200ml children's juice boxes, which contain about 17g sugar, the equivalent of more than four teaspoons.

The biggest problem with juice, as far as Lustig is concerned, is the lack of fibre. When you eat a whole apple, the sugar is 'nicely balanced' by the fibre, giving 'the liver a chance to fully metabolise what's coming in'. When you down half a pint of apple juice it 'brings a huge dose of energy straight to the liver'. Smoothies are not much better, no matter how pretty the packaging, because when fruit is blended the insoluble fibre is 'torn to smithereens'.

This news is galling for righteous types like me, who in the past have given their children lectures on the evils of fizzy drinks while smugly feeding them 'pure not-from-concentrate juice'. If I tried to ban juice in our family now, there'd be uproar. The most realistic course seems to be moderating the dosage. I notice that the juice-box manufacturers have started doing this too: Tropicana Kids cartons come with 25 per cent water added. But you may as well do the diluting yourself. In our house, juice is – on a good day, anyway – for breakfast only, with a third water to juice. What's striking is how quickly drinking watered-down juice changes your palate. 

Nowadays, when I take a sip of the hard stuff, it tastes nearly as undrinkably sweet as undiluted squash.

Im sure you're beginning to wonder "what on earth could then be good for us if scientists say everything is bad ?"