Do you remember how they used to describe Irn-Bru?

"Made in Scotland from girders." (For maximum effect, it was necessary to roll the Rs heavily.) Of course, it was nothing of the kind. Made in Scotland, certainly, but from water, sugar and a mysterious orange dye that you can never ever get out of your son's bedroom carpet. I have the stain to prove it and occasionally muse that the digestive systems of heavy consumers of "Scotland's other national drink" must be the shade of Belisha beacons.

So how do I feel about the news that AG Barr has been named as an official sponsor of the Glasgow 2014 Commonwealth Games? Conflicted, frankly. Hats off to Glasgow 2014 and the Scottish Government for ensuring the majority of contracts have gone to Scottish companies. (I'm mystified that more effort isn't going into encouraging us all to buy Scottish, when it's an option.) And Barr's is a Scottish success story and an impressively well-run outfit. On occasion, Irn-Bru outsells Coca-Cola in Scotland, which is quite a feat. My younger daughter's favourite ever school trip was to their huge, immaculate plant in Cumbernauld and as a family, we enjoy their edgy, self-mocking advertising.

On the other hand, what sort of message will this sponsorship deal send out? The Olympic torch relay would have been fantastic had it not been turned into a huge 70-day rolling advertisement for Coca-Cola. For "Higher, Stronger, Faster", read "Fatter, Fatter, Fatter" because, let's face it, sugar is the new threat in the fight against flab and Britain's (especially Scotland's) massive consumption of fizzy drinks is heavily implicated. There was lots of talk yesterday about the million bottles of its Strathmore water that would be supplied by Barr's to the Commonwealth village but nobody should be fooled. Barr's is about the fizzy, orange liquid that makes up 60% of its business and most of its growth prospects. (Why were the company's first-half profits down? Largely because of the rise in world sugar prices.)

The British consume more than two million tonnes of sugar each year, three quarters of it indirectly in confectionery, processed foods and drinks. In 1985 we consumed 10 gallons of soft drinks per head per year. Now it's 25 gallons (or 14 billion litres). I once read that only Israeli children gulp down more fizzy drinks than Scottish ones. With cut-price deals on multi-buys of two-litre bottles on almost permanent special offer in supermarkets, it is no longer a special treat in most households. Yet would parents let their kids guzzle those 550ml cans if they knew each one contained the equivalent of 10 teaspoons of sugar?

Tobacco advertising of sporting events is now unthinkable. So why allow fizzy drinks that do nothing to improve sporting prowess and, consumed regularly, are big contributors to tooth decay and obesity, with its associated health problems, including heart disease, cancer, bone and joint problems, diabetes and sleep apnoea. Yesterday a Japanese study linked fizzy drinks to life-threatening strokes in women. Sport Minister Shona Robison is apparently delighted with the Barr's sponsorship deal. What about Health Secretary Alex Neil? How is this deal going to contribute to the Games legacy in a country where only one adult in three is not overweight or obese? How is it going to improve the health of men near the games site in the east end of Glasgow, who have the lowest average life expectancy in Britain (less than 60), when Irn-Bru advertising is splattered across the neighbourhood? Is the presence of such brands simply the price we pay to see world class sport?

If you'll excuse the pun, I reckon we're setting the sponsorship bar too low for such a major event. A few months ago there was serious discussion about what was dubbed "the Irn-Bru tax" to steer young consumers away from sugar-laden fizzy drinks. The idea came from the Scottish Collaboration for Public Health Research and Policy, who described it as "something the Scottish Government can't afford not to look at". What chance of that now? None.