We all know that confectionary and fizzy drinks are bad for our teeth. But damaging sugars also lurk in healthy foods, such as fruit. Hilly Janes bites back at a sticky dental situation

I have just been to the dentist. He gave me three enormous fillings and told me off for eating too many sweeties. No, I am not an 11-year-old. I am 47. People of my age shouldn't need fillings, he says. It's all down to my diet.

As I squirmed in the chair – with embarrassment, not pain, he's an excellent dentist – he asked me whether I consume lots of fruit or juice. I have only just started visiting Neil Stephen, who practises privately in central London. Sadly, I couldn't blame my cavities on such healthy habits. Only an ostrich could be unaware of the medical profession's advice to eat five portions of fruit and veg a day to help prevent cancer and heart disease, but I don't like fruit, so that can't be the problem. What about fizzy drinks? True, I like the odd Diet Coke, but several cans went down the sink recently, because they'd been in the cupboard for so long that they were past their sell-by date. So it can't be the fizzy drinks.

It's not that the decay came as a shock. I've been having fillings since I was seven, not to mention braces, abscesses, root-canal treatment, crowns and veneers. But I've always managed to make excuses for myself. Even though this was my first check-up for several years – work, small children, you know how it is – I wasn't quite expecting the price to be three hour-long drilling and filling sessions.

Perhaps it was having a baby, I suggested. Everyone knows it diverts your calcium, and I'm so desperate for excuses that I'll even pass the buck on to a helpless infant. This, according to Mr Stephen, is a myth. Hormonal changes can increase the risk of gum damage, but constantly tasting sweet baby foods is a more likely cause of decay in mothers of young children.

Did I suck sweets, he prompted? Who, me? Never! Then I remembered the Mintoes. These were dispensed to our son on country walks when he was still very small. There's nothing like a boiled sweet to keeping you going, I said to myself as I sucked away. Soon there was a bag of sweets in the car for long journeys, or even for quite short journeys. Eventually my husband (he's very hot on dental hygiene) insisted that I stop, for the sake of my teeth. I still haven't 'fessed up to Mr Stephen.

Would I like to fill in a diet sheet over three days, recording everything I was eating? he asked, helpfully. The problem is, I would cheat. The sheet would possess magic powers that propelled me away from the biscuit tin at tea-time and suppressed the overpowering desire after lunch to raid my son's Treat Box, where we stash the edible contents of party bags for once-a-week rations.

It was time to face facts. It's not that I was eating vast quantities of anything naughty; it's nibbling throughout the day that does the damage. "Bacteria that live in the mouth feed on the sugars, and their waste product is acid that makes holes in your teeth," Mr Stephen explains. "Saliva will mend the hole within 24 hours, but if you consume more sugar within that time, the saliva will not be able to cope. It's all microscopic, but over time the effect builds up." Brushing your teeth straight afterwards doesn't help, he explains, because the teeth have been softened by the acid, so you are brushing away their surface.

Mr Stephen suggests limiting "tooth-attacking" stuff to once a day. If biscuits are your weakness, for example, you are better off scoffing a couple, rather than nibbling your way slowly through half a packet. There's another myth that sweet treats after meals are less damaging, but it's not when, but how often, that counts. The same goes for fruit and juice, as the acid also eats away at the teeth, although if you eat it within a meal it is diluted.

How are we to reconcile the dentist's advice with the doctor's orders to eat all those apples every day? Jane Clarke, a state registered dietician and the author of the Body Foods books on healthy eating, accepts that fruit can damage your teeth, but stresses that its ability to combat life-threatening diseases outweighs the potential harm.

"As long you are not drinking more than a glass of freshly squeezed juice or a couple of portions of fruit a day, then you should be OK," she confirms. It is probably wiser to major on the vegetables, because they offer a wider range of nutrients.

Some people can eat sugar with impunity – thanks, in all probability, to their genes. Lucky them. All the same, I have much to be grateful for. Three of my teeth have been rescued, and I have been shown how to improve my brushing and flossing. The dentist has even given me a cute new toothbrush. It has a very dainty head and it is bright pink. Eat your heart out, Barbie – just keep off the sweet stuff.