It's a kneejerk British reaction. As soon as children squirm in their pushchairs, raising a querulous voice or complaining of thirst, we thrust something sweet into their sticky little hands. Sweets, biscuits, cakes, fizzy drinks - all are props to modern parenting. We trade sugar for peace and complicity. But it doesn't last: the short-term saviour becomes a sugary trap.

The toddler initially silenced by sweets becomes a monster once the sugar fix has worn off. They grow into children who say they don't like the taste of water because it's "plain" or an orange because it's too sour. Sugar can wreck a child's health. Excess sugar is converted to fat and leads to obesity. Obesity leads to more disease, such as diabetes.

Sugar also helps make foods loaded with fat and carbohydrate more tasty and these supplant more nutritious foods in a child's diet. No wonder that by 16, one in four British children is overweight. Then there's dental caries. It costs the taxpayer twice as much as heart disease and children are uniquely vulnerable because their teeth are still soft. Half the children in the UK aged 7-10 have tooth decay. This is not news to health-conscious parents, some of whom now favour low-calorie, artificial sweeteners as a solution.

Unfortunately sweeteners are a minefield too. OK, they don't rot teeth, but some scientists believe they act as appetite stimulants. In other words, a "diet" drink can make your child feel like eating a bar of chocolate. And the high phosphorous level in such drinks is implicated in weakening bones and causing osteoporosis. Not even honey, molasses, syrup and fruit juices are safe - damage teeth too.

So how much sugar can a child eat and stay healthy? The latest EU proposal is that children should eat sugary foods no more than four times a day, reflecting dentists' thinking that frequency of sugar consumption matters more than quantity. Nutritionists say sugar should account for no more than 10% of an adult's energy needs and probably less for children. The government's long-awaited survey of British children's diets recently revealed that sugar accounts for 16-17% of the average child's energy, with some clocking in at 30%.

That is no surprise given the confusion that reigns, in part thanks to advertisers. The health coalition, action and information on sugars, complained to the advertising standards authority that the claim that Ribena was "tooth-kind" was misleading. Last month the complaint was upheld. Ribena are to appeal. But can you blame a parent for thinking it was good for teeth when packs carry the endorsement of the British dental association?

Sugar turns up in some bizarre places. "Canned vegetables and sauces such as brown sauce and ketchup are the two most hidden sources," says Lord Rodgers, chairman of the advertising standards authority, "then come soft drinks, biscuits and baked goods, ice cream and dairy foods like yogurt, canned fruit, jams, sauces and confectionery."

Too many British children have become accustomed to foods with very high levels of sugar and parents do need to try to curb that sweet palate if they want to safeguard health. Parents are probably more of a problem than children themselves, many thinking the natural flavours of good food cannot be enjoyed unless they are very sweet or have added sugar. This is nonsense. It is perfectly possible to raise a child who prefers a clementine to a cola chew, or even to convert a child with a developed taste for sweet junk food.

If you really want your children to give up sugar, they will, but you need to believe you can do it."We have forgotten that water is the number one fluid for thirst quenching," says Dr Wendy Doyle of the British dietetic association.

Do not buy high-sugar foods or routinely keep them in the house: score sweet drinks, biscuits and sweets off your shopping list. Buy as little processed food and as much fresh food as you can and feed children from the same store of food as the adults. Children who raid the fridge for fizzy drinks or empty the biscuit tin are not satisfied nutritionally. In no time they will want more to eat and it's likely to be more junk. Soup, a decent sandwich, leftovers and fruit will make them much more biddable and contented, and in the long-term, infinitely more healthy.

The Food Our Children Eat, by Joanna Blythman, is published by Fourth Estate at £7.99.