By Russell Findlay

Children who expect chocolate behind the doors of their advent calendar may be surprised to learn that previous generations made do with nothing more than a festive picture.

But in recent years, there has been a rise in the variety of advent calendars containing chocolate and other sweets.

While many parents and children view the daily treat as a harmless tradition in the countdown to Christmas, concerns have been raised about the amount of sugar being consumed.

STV News found that supersize advent calendars on sale this year can contain up to 300g of confectionery.

A standard Cadbury's calendar typically contains 90g of chocolate compared to 232g in its Cadbury's Heroes product.

From Mars, the M&M's & Friends calendar has 290g while its Celebrations offering contains 230g.

Haribo sells a calendar with 300g of its jelly sweets and chews while Nestlé has a Quality Street calendar with 229g of chocs and Smarties with 227g.

Professor Mike Lean, chair of human nutrition at Glasgow University, does not want to be seen as a scrooge - but has concerns the increasing consumption of sweets at breakfast time.

He said: "This is crass opportunism by a food industry which is wanting to put its products in front of children every day.

"They are all part of normalising an aberrant and damaging behaviour, eating sweets whenever there is a quiet moment.

"And using advent calendars is terribly sad. The whole idea of advent is it's a build up to something exciting.

"In my day, and my children's days, advent calendars were exciting, showing a wee picture each day of an anticipated Christmassy thing. We all had different pictures each day.

"Now it appears to be a build up of more sweeties and more chocolate until Christmas, which is all chocolate.

"Of course, these calendars are also advertising on the front of them the companies. This is just marketing now.

"No child is suddenly going to get obese from eating one sweetie a day but it's normalising sweeties every day."

Malcolm Stewart, a senior clinical lecturer at Aberdeen University dental school, said that children's teeth can take a 'hit' over Halloween - quickly followed by Christmas.

He says that children's dental health in Scotland is improving, due partly to greater parental awareness.

And he suggests that parents should allow advent calendars with sweets, but should avoid them being eaten in the morning.

He said: "We're not saying to parents no chocolate or no sweets at all, but have a think about when they're getting the treat from the advent calendar.

"If possible, have it with a meal but try to avoid it at breakfast time or a time that's not appropriate.

"We know if children are snacking throughout the day, that's the time when there's problems because their teeth will decay for around half an hour every time they have chocolate."

He also raised concerns about children being gifted numerous calendars by relatives.

He added: "Parents are generous, grandparents want to help out and be involved as well. Sometimes children are getting more than one advent calendar, maybe two or three."

Responding to the criticism, Nestlé say this year they have introduced a Milkybar Wowsomes calendar with a 30% reduction in sugar.

A spokesperson said: "Families can choose to share door opening duties around different family members and we always make sure that portions in our calendars are smaller than a standard portion of each product. "

A Mars spokesperson said: "Our core range of advent calendars remains the same size as in previous years. They are designed to give people a little festive treat every day in the lead up to Christmas."

A spokesperson for Cadbury owner Mondelēz International said: "We believe our role is to encourage balanced snacking by providing clear nutrition information to consumers on front of pack, promoting healthy lifestyles and improving the nutritional profile of our products.

"We always encourage our consumers to be treatwise and our Cadbury calendars contain individual chocolates that are designed to be eaten once a day and are less than 100 calories, as advised by Public Health England."

A Haribo spokesperson added: "At Haribo we believe that sweets are a treat to be enjoyed in moderation or as part of a special occasion.

"Our advent calendar is celebratory and festive with each window offering a small, portion-sized treat to be enjoyed as part of the traditional countdown to Christmas."