The apparent reason for the plane trip was that Kellogg's was launching Kashi, a brand of mixed grain puffed cereal free of all additives, in the UK. Criticism of the food industry for selling products high in fat, salt and sugar had reached a crescendo and cereal manufacturers, who prided themselves on their health associations, were receiving unwelcome attention. The Kashi brand was a crucial part of Kellogg's long term plan to protect its portfolio - but a wider strategy had also formed.

Before touring the factory with its vast steel pressure cookers, miles of pipes carrying vitamins and flavourings, stainless steel rollers and high temperature toasting ovens, reporters were ushered past a giant Tony the Tiger cutout in the entrance lobby and up into the nerve centre of planning for a presentation on nutrition policy and labelling.

Perhaps it was also in the strategic planning department that Kellogg's carried out an audit of its products, an audit that all food manufacturers must have undertaken when the Food Standards Agency published its criteria for defining how different foods would be rated. The results would determine how food would be rated under both the FSA's red, amber and green traffic light labelling and the nutrient profiling that will determine which products broadcasting regulator Ofcom will ban from being advertised on television to children from next month.

A similar but informal audit of products taken by Ofcom had thrown up some startling results. The watchdog had wanted to see how much television advertising would be vulnerable if it applied a ban on promoting products which the FSA defined as high in fat, salt, and/or sugar before the watershed.

How many red spot foods appeared on TV before 9pm in 2005? What became clear was that about £70m worth of adverts from cereal manufacturers a year would be banned. The sector spent £84m on ads that year: under the new rules the vast majority of its marketing effort would be wiped out. Kellogg's, the largest seller of cereals in the UK, spent the most on advertising in 2005 - nearly £50m. Cereal Partners, which markets the Nestle brands in Britain, was the second highest spender with £20m in the same year.

The next most vulnerable category would be yoghurts and fromage frais - similarly sold largely on a health ticket. At least £39m of TV ads a year would have to go because they were for products the FSA model would deem junk.

Health claims

The stakes for the food industry could not be higher. The British and Irish are the biggest eaters of puffed, flaked, flavoured, shaped, sugared, salted and extruded cereals in the world. We munch an average 6.7kg of the dehydrated stuff a person a year in the UK, and 8.4kg each in Ireland, according to figures from Datamonitor. The UK's breakfast habit is the child of advertising. The market for the cereal boxes which find their way into more than 90% of households here, worth £1.27bn in 2005, has been created and maintained by advertising characterised by health claims since the early 20th century.

With red labels on the packets, we might start questioning these health claims. Without the advertising to promote them, we might never know that we need processed cereal and revert to porridge or bread instead.

The cereal industry is adamant that its products are being unfairly demonised. "It can't be right that a whole category is taken out that way. Breakfast cereals are important for children, many of whom would otherwise skip breakfast altogether," Kellogg's communications director, Chris Wermann, says. Kellogg's has by its own admission led the drive to bring in an alternative form of labelling the industry can live with. The cereal manufacturer has also been at the heart of a lobbying campaign against the proposals from Ofcom and FSA that senior regulatory officials have described as "the most ferocious we've ever experienced".

In May, the consumer watchdog Which? published a survey which shed further light on why the industry was so worried about traffic light labelling. It analysed 275 big name breakfast cereals from leading manufacturers on sale in UK supermarkets. Despite industry claims to have reformulated their recipes to make their products healthier, Which? found 75% of them still had high levels of sugar, and almost a fifth had high levels of salt, according to FSA criteria. That 75% would all receive red labels.

Nearly 90% of those targeted at children were high in sugar, 13% high in salt, and 10% high in saturated fat. Several cereals making claims to be good for you received red lights too. All Bran was high in salt when surveyed, although Kellogg's says it has reduced levels since then. Special K gets a red light for sugar and salt.

Tom Sanders, professor of nutrition at King's College London, who acts as a consultant to the cereal manufacturers, believes traffic light labels "unfairly misclassify breakfast cereals", because they do not take into account portion sizes nor the fact that they are being measured on dry weight while they are mostly eaten with milk. "Breakfast cereals served with semi-skimmed milk are low energy meals that provide about one fifth of the micronutrient requirements of children and should be encouraged," he said in a briefing for the industry's breakfast cereal information service.

Back in the Kellogg's strategic planning department in April 2005, company nutritionist Alyson Greenhalgh was explaining its policy on health to the small gathering of journalists.

The company had decided to take a lead and promote a new kind of labelling to help "mum" make healthier choices, she explained. Rather than using the traffic light coding the Food Standards Agency was researching, Kellogg's and other leading food manufacturers had decided to go live with a system of labels, which have been rejected by the FSA, based on guideline daily amounts (GDAs). These would avoid identifying foods as good or bad with red, amber and green, and instead give figures for how much fat, salt, and sugar a portion of the product contains as a proportion of a guideline amount you should eat each day of those nutrients. In response to pressure from the FSA, the Association of Cereal Food Manufacturers had already reduced salt by a quarter in five years, she said.

Blind tests

Cornflakes were even "tastier than before" in blind tests because you could taste the corn more, and salt levels had dropped from the equivalent of 12% of the guideline daily allowance in 1998 to 9% in 2005, she said.

But why was there so much salt in the cereal in the first place?

The managing director of Kellogg's Europe, Tony Palmer, said that "if we'd known you could take out 25% of the salt and make cornflakes taste better, we would have done it earlier. But it's also about the interaction with the sugar - as you take the salt out, you've got to reduce the sugar because it starts to taste sweeter."

But sugar helps keep the flakes crispy and is part of the bulk, so going further is difficult. "And the risk is, if you take the salt out you might be better off eating the cardboard carton for taste," he said.

As well as educating journalists, Kellogg's has been lobbying MPs, ministers and regulators. The PR agency Hill and Knowlton boasts on its website how it managed to change government and Whitehall thinking on Kellogg's behalf.

"A series of meetings with No 10, the Department of Health, the Food Standards Agency, the health select committee, one-to-one briefings with key individuals and an event for parliamentarians" enabled them to disseminate Kellogg's messages. "The campaign resulted in a significant shift in attitudes among core government stakeholders," the agency says. Kellogg's had met the public health minister, Caroline Flint, on December 14 2005, together with the chair and deputy chair of the FSA. It submitted a detailed response to Ofcom's proposals, arguing that breakfast cereals should be considered a special case and that the FSA's nutritional profiling model was scientifically flawed.

Lobbying

The event for MPs - a breakfast at the House of Commons - took place on January 18 this year. At it, Kellogg's European president, Tim Mobsby, reminded MPs that Kellogg's was a large employer in the UK and recalled the company's credentials: "W Kellogg started selling breakfast cereals to patients in a sanatorium in order to provide healthy and nutritious meals for his patients." Cereals, he said, are fortified with vitamins and minerals and if eaten with milk provide significant intakes of calcium and iron.

At the political party conferences in autumn this year, officials from the regulators wanting to explain their proposals to Whitehall, government, and opposition figures, found "Kellogg's nearly always seemed to have been a few hours ahead of us lobbying for GDAs. They muddied the waters for us. Frontbench spokespeople told us they'd never experienced anything like it in terms of lobbying," said one senior insider.

The FSA is in little doubt that the concerted attempt by industry to derail its traffic light labelling by actively promoting its own rival scheme marks the beginning of a new phase in the long battle to improve the UK diet.

For the industry, it is a fight in which they have everything to lose.

Breakfast cereals today remain what economic analysts call a "high margin-to-cost business". One of the biggest costs is the marketing, which is typically 20-25% of the sales value, according to analysts JP Morgan. Gross profit margins on processed cereals are 40-45%.

Seventh Day Adventists took up the mission begun by Graham in a small town called Battle Creek in Michigan.

One of them, John Harvey Kellogg, set about devising cures for what he believed were the common ills of the day - constipation and masturbation. In Kellogg's mind the two were closely linked, the common cause being a lack of fibre, both dietary and moral.

Kellogg, his wife, and his brother William experimented in their sanatorium kitchen and came up with their own highly profitable version of Granula. The experiments continued, Kellogg's fame grew, and the first version of cornflakes was created - though they did not sell well.

Then Charles Post, a chronically dyspeptic entrepreneur who had been one of Kellogg's patients, developed his own precooked cereals. His genius was to harness the power of marketing. "The sunshine that makes a business plant grow is advertising," he said. He distributed tracts with his products with such encouraging titles as The Road to Wellville and cheerfully invented diseases they could cure. By 1903 he was making over a million dollars a year and Battle Creek had turned into a cereal Klondike. At one point there were more than 100 cereal factories operating in the town to satisfy the new craze.

John Harvey Kellogg was more interested in his crusade against sexual sins and bad eating than making money, but his brother William felt differently. Eventually W Kellogg persuaded his brother to set up a new company to manufacture cornflakes for the mass market. The two disagreed over whether to make their cereals palatable by adding sugar - anathema to John, needed to stop the products tasting like "horse-food" by William - and over who owned the cereal name.

In the end William succeeded in gaining control. The legacy of the cereal goldrush is still there in Battle Creek today, though the factories have mostly gone. In their place is Kellogg's Cereal City, a museum testament to the power of marketing.

The collection of early cereal boxes show that from the first they sold not just a meal but a way of life: Power, Vim, Vigor, Korn-Kinks and Climax are among the early brand names. Early packets also carried health claims that anticipate today's. "Will correct stomach troubles!" "Makes red blood redder!"

Crackley soundtracks from some of the first radio programmes in the 1920s record the sponsorship deals that helped the new medium and the cereal business grow: "Kellogg's cornflakes announces another thrilling new adventure ..."

Kellogg's also sponsored the singing Lady programme for children. In 1931 artist Vernon Grant created drawings depicting the characters Snap, Crackle and Pop, and cartoon merchandising was born. Giveaway toys were used too to attract children's loyalty.

Cereal advertising also helped shape early television. A chance meeting on a train in 1949 between the then chairman of Kellogg's and advertising man Leo Burnett led to a relationship that transformed the cereal market and TV ads. Burnett used "motivational research" to work out how to appeal to women and children, changing packaging colours to attract different audiences subliminally. With his help, Kellogg's broadcast the first colour TV programmes and commercials for children.

The Battle Creek Museum also states Kellogg's vision for the future. Under a section on "global expansion" it notes that 90% of the world's breakfast cereal is consumed in just a handful of countries: "The company has rededicated itself to reaching 1.5 billion new cereal customers around the world in the next decade ... and bringing about a fundamental change in eating habits."

Steamed wheat biscuits

Shredded wheat is made from whole wheat grains which are pressure cooked with water and then passed between rollers to squeeze them into strands and build them up into layers, which are then cut into squares and baked until dry. Weetabix-type cereals are similarly steam cooked whole grains with salt and sugar, rolled very thinly and then pressed into biscuits. These processes begin the breakdown of the raw starches in the cereals, so they are absorbed more quickly in the body - they typically have glycaemic index scores of around 75, compared with 45/46 for unprocessed grains such as porridge or mueslis without sugar.

Puffed cereals

Puffed cereals were invented by Alexander Anderson for the Quaker Oat Company at his laboratory in Chicago. He began with rice heated in a sealed test tube which exploded. Several detonations later, he and his engineer adapted a breach loading recoiling cannon to mass produce puffed or exploded grains. Today's adaptations of the technology are giant sealed cylinders that heat the grains to high temperatures. When they are unsealed the steam pressure in each grain causes it to expand, and they are dried before they collapse. As with corn, rice has its essential oils removed during milling to make long life processed cereal.

Extruded cereals

Cereals shapes are made from flours that have been finely milled. They are mixed with water and heated then extruded though holes so that they expand into their final shape. The heating and mechanical working of the cereals breaks down the starch cell structure, so they tend to have higher GI values. Vitamins destroyed in the heat process are added to the mixtures along with sugar, salt and flavourings, or sprayed on. Wholegrain cereal shapes can be made from whole grains milled to a powder or from recombined fractions of flour milled to white.

Acrylamide

Cereal processing involves heating cereals to high temperatures. In 2002, a survey by the Food Standards Agency found a compound called acrylamide, known to cause cancer in animals and a probable human carcinogen, was formed in some starchy processed foods, particularly during the toasting process. Wheat-based cereals tend to have higher levels of acrylamide. The industry has been trying to reduce levels without much impact, according to reports. The FSA advice is that exposure to acrylamide should be kept as low as possible.

Fortification

Vitamins were first added to breakfast cereals in the early 1930s, first the "sunshine vitamin" D, and later fragile, heat-sensitive B vitamins, and vitamin C and iron. A new wave of fortification is coming. Inulin, known to the food industry until recently as a bulking agent, is now added as a "prebiotic", and companies are looking at adding omega-3 fatty acids such as DHA. There are technical difficulties - the long chain molecules in DHA can be damaged by high temperatures and pressure processes. Firms have worked out how to take a dairy protein and carbohydrate to form a slurry with tuna oil, which is spray dried to encapsulate DHA.

The campaign is a direct response to a concerted attempt by leading food manufacturers and retailers, including Kellogg's and Tesco, to derail the system. The industry fears that traffic lights would demonise entire categories of foods and could seriously damage the market for those that are fatty, salty or high in sugar.

The UK market for breakfast cereals is worth £1.27bn a year and the manufacturers fear it will be severely dented if red light labels are put on packaging drawing attention to the fact that the majority are high in salt and/or sugar.

The industry is planning a major marketing campaign for a competing labelling system which avoids colour-coding in favour of information about the percentage of "guideline daily amounts" (GDAs) of fat, salt and sugar contained in their products.

The battle for the nation's diet comes as new rules on television advertising come into force in January which will bar adverts for unhealthy foods from commercial breaks during programmes aimed at children. Sources at the TV regulators are braced for a legal challenge from the industry and have described the lobbying efforts to block any new ad ban or colour-coded labelling as "the most ferocious we've ever experienced".

Ofcom's chief executive, Ed Richards, said: "We are prepared to face up to any legal action from the industry, but we very much hope it will not be necessary." The FSA said it was expecting an onslaught from the industry in January. Senior FSA officials said the manufacturers' efforts to undermine its proposals on labelling could threaten the agency's credibility.

Terrence Collis, FSA director of communications, dismissed claims that the proposals were not based on science. "We have some of the most respected scientists in Europe, both within the FSA and in our independent advisory committees. It is unjustified and nonsensical to attack the FSA's scientific reputation and to try to undermine its credibility."

The FSA is understood to have briefed its ad agency, United, before Christmas, and will aim to air ads that are "non-confrontational, humorous and factual" as a counterweight to industry's efforts about the same time. The agency, however, will have a tiny fraction of the budget available to the industry.

Gavin Neath, chairman of Unilever UK and president of the Food and Drink Federation, has said that the industry has made enormous progress but could not accept red "stop" signs on its food.

Alastair Sykes, chief executive of Nestlé UK, said that under the FSA proposals all his company's confectionery and most of its cereals would score a red. "Are we saying people shouldn't eat confectionery? We're driven by consumers and what they want, and much of what we do has been to make our products healthier," he said.

Chris Wermann, director of communications at Kellogg's, said: "In principle we could never accept traffic light labelling."

The rival labelling scheme introduced by Kellogg's, Danone, Unilever, Nestlé, Kraft and Tesco and now favoured by 21 manufacturers, uses an industry-devised system based on identifying GDAs of key nutrients. Tesco says it has tested both traffic lights and GDA labels in its stores and that the latter increased sales of healthier foods.

But the FSA said it could not live with this GDA system alone because it was "not scientific" or easy for shoppers to understand at a glance.