"Salt is a silent killer," says Professor Graham MacGregor of St George's Hospital, London, the cardiovascular specialist I spoke to when researching my OFM story about the hidden dangers in middle-class children's diets. "When you eat more salt, you retain more fluid" – an extra 1.5kg of liquid that is "sloshing around inside you and putting your blood pressure up, then suddenly, oops, you've had your stroke or heart attack and you're dead."
High blood pressure accelerates atheroma – the build-up of furry deposits in the arteries that causes strokes and heart attacks. Disturbingly, the early signs of "atheroma streaking" are found during post-mortems on children who have died in accidents – some of them as young as three or four years old.
Not all of these are children raised on the calorie-rich fast food often blamed for the ticking timebomb of obesity, high blood pressure, diabetes, heart disease and even cancer. It's all too easy to criticise the diet of people represented in programmes such as Jamie Oliver's Ministry of Food, but the problem is much broader. My focus was on kids who eat a diet of things like breakfast cereals, toast and Marmite, croissants, cereal bars, pasta with sauce, ham sandwiches and sausage and mash – in other words, a typical middle-class child's diet.
Salt is hidden in all manner of seemingly healthy foods, as are sugar and refined carbohydrates that pile on calories but offer little in the way of nutrition.
Hence the government's £275m Change4Life campaign, aimed at tackling obesity (and by implication all the above diseases) in every section of society, launched in January with TV advertisements by Aardman Animations, the creators of Wallace and Gromit.
"We want families to engage with the campaign and understand that obesity is not someone else's problem," said public health minister Dawn Primarolo at the launch - but I'm not sure I would have really noticed the Change4Life campaign if I hadn't been researching this story.
Was the campaign prominent enough? Has it changed the way you shop, cook or live? Was it a big enough investment? Overweight and obese people cost the NHS £4.2bn a year to treat, and the cost to the wider UK economy is £16bn, so in that context £275m doesn't seem a lot. The bigger joke is that £200m of it was put up by food companies such as Kellogg's and Pepsico, manufacturers of some of the least healthy foods for children.
Their initiatives focus more on sport and activity than they do on diet. Pepsico (Pepsi, Walkers, Tropicana) is promoting "active play", Kellogg's has a Swim4Life programme and Asda a Bike4Life initiative. It all calls to mind the Cadbury's Get Active campaign of 2003, which offered £9m-worth of sports equipment to schools in return for tokens on sweet wrappers.
"If you make chocolate, you are not going to put money into any campaign that directly tells people not to eat chocolate," says Dr Ian Campbell, a Nottingham GP and medical director of the UK charity Weight Concern. "You will put it into promoting physical activity to negate the harmful effects of eating too much chocolate. It is the only choice these companies have."
Dr Campbell even believes the food industry unwittingly sabotages the government's efforts to get the healthy-eating message across. "You drive past a bus stop and there is a lovely billboard promoting the Change4Life concept," he says. "Immediately beside it is one from a company offering a 99p burger. Any impact is almost negated by the efforts from the other side."
Is it wrong to blame manufacturers for peddling unhealthy food to children when it is we, their parents, who demand convenience foods because we are too time-poor or career-obsessed to cook? And are the food companies and the government genuinely at odds, or is there a comfortable alliance between them?