In my previous job, as editor of EU Food Law, I conducted the interview with Tim Smith, chief executive of the Food Standards Agency, that the article referred to. Your commentators are perhaps too swift to dismiss the idea as a complete non-starter.
President Obama is proposing a tax on soft drinks to fund healthcare. Denmark is proposing a saturated fat tax on certain foods, such as some dairy products, and it already has one on soft drinks. Romania is also proposing a tax on a range of "unhealthy" foods, although so far it has not published a list of the foods or the level of tax.
Furthermore, the UK is unusual in that most food is zero-rated for VAT so some scope there. Mr Smith specifically mentioned VAT rates when I interviewed him.
Given the state of the public finances, whichever party wins the election the next government will be looking for revenue-raising ideas.
I do agree with your commentators that it would be very complex and controversial. Mr Smith said any tax must not be regressive, people must have a choice tap water (free) or sweetened drinks (taxed). But just because it is difficult does not mean that the FSA board will be deflected.
I would not write it off quite yet.
Kate Trollope, editor, www.eufoodpolicy.com