Some yoghurts contain so much sugar that they would nearly send children over their daily limit, an NHS study has revealed.

The NHS says children aged between four and six should have no more than 19g or five cubes of free sugar (sugar not "locked in" naturally to products) a day, while seven-to-10-year-olds should have no more than six cubes.

But a study by Public Health Liverpool has revealed that some yoghurts contain the equivalent of almost five sugar cubes in a single serving, reports the Manchester Evening News .

Now the organisation, backed by campaign group Food Active, has launched a campaign to highlight the findings and tackle childhood obesity.

Beth Bradshaw, from Food Active, said: "The issue with fruit in a lot of pre-packaged yoghurts is that it has been processed and altered to be almost unrecognisable.

"Yoghurt is such a healthy and delicious food to give children. It should feature in their diet on a daily basis because it's full of calcium, which helps promote healthy bone development and is a really good source of protein.

"The golden rule is to opt for plain yoghurt as a starting point - plain low fat Greek and natural yoghurts are delicious and are much lower in added sugars. Plus you can add in your own tasty fruit flavours just the way your child likes them."

The study found that some yoghurts had the equivalent of almost five sugar cubes in a single serving

Dr Sandra Davies, Liverpool's director of public health, said: "Tackling sugar in diets is a real priority because we know that people simply don't realise how much they are consuming.

"If we are to stand any chance of tackling this ticking time bomb, we must give parents as much information as possible so they can make informed decisions.

"Most people don't have the time to read labels when racing around the supermarket to complete their weekly shop, and so we have to support them to make healthier choices."

The number of sugar cubes in popular yoghurts, as analysed by Public Health Liverpool

4.9 - Muller corner

4.7 - Aldi Brooklea (own brand)

4.5 - Asda own brand

3.3 - Smarties (Nestle)

2.6 - Ski (Nestle)

2.2 - Lidl Milbona (own brand)

2.1 - Petits Filous (Yoplait)

2 - Munch Bunch (Nestle)

Each cube = 4g of added sugar

Some yoghurts contain the equivalent of almost five sugar cubes
Some yoghurts contain the equivalent of almost five sugar cubes

What you need to know about caring for your children's teeth

With concerns that high levels of sugar are also leading to an "alarming" level of tooth decay in youngsters, Adlyn Burton, dental hygienist and therapist at Love The Dentist , stressed the most important points when caring for children's teeth:

  • Brush twice a day, preferably with an electric toothbrush with a rotating head
  • Parents should help children brush their teeth up to the age of seven
  • Use a toothpaste containing fluoride to protect against cavities
  • Have a sugar free diet in between meals, including sugar free drinks

She said: "One of the biggest problems with children's teeth is tooth decay.

"We do have a lot of children that come through who require a lot of extractions or fillings and it's easily preventable at home if you brush your children's teeth properly."

Research from Mydentist shows that parents use a range of methods to encourage their kids to brush their teeth.

These range from singing songs, to reward charts and gimmicky toothbrushes. A quarter use the threat of teeth falling out.

Mum-of-two Rebecca Bennett has found that watching Colgate's Two Minute Tales while brushing teeth has helped her children Katie, six, and Emma, two.

Colgate has partnered with Claire Freedman, author of the hugely popular Aliens Love Underpants series, to launch the tales.

The short stories can either be read by parents while little ones brush their teeth, or can be watched online via a tablet in the bathroom.

Parents can choose between reading the stories themselves or letting kids listen to them via tablet, phone or desktop, with the aim of turning 'two minutes of teeth brushing into two minutes of fun'.

To find out more about the Colgate tales visit www.ColgateTwoMinuteTales.co.uk .