They are ultra processed and the extra iron has been added to make up for it.
"That processed cereals had become little more than sugary junk with milk and vitamin pills added, was an accusation made as long ago as the 1970s. A US congressional hearing in 1970 was told by an adviser to President Nixon on nutrition, Robert Choate, that the majority of breakfast cereals 'fatten but do little to prevent malnutrition'. Choate was outraged at the aggressive targeting of children in breakfast cereal advertizing. He analysed sixty well-known cereal brands for nutritional quality and concluded that two thirds of them offered 'empty calories, a term thus far applied to alcohol and sugar'. Rats fed a diet of ground-up cereal boxes with sugar, milk and raisins were healthier than rats fed the cereals themselves, he testified to senators."
"Many of the health benefits claimed for breakfast cereals depended on fortification rather than micronutrients from the raw ingredients, most of which were either destroyed by the process or stripped away before it."
"Cornflakes are generally made by breaking corn kernels into smaller grits which are then steam cooked in batches of up to a tonne under pressure of about 20lbs per square inch. The nutritious germ with its essential fats is first removed because, as the Kellogg brothers discovered all that time ago, it goes rancid over time and gets in the way of long shelf life. Flavourings, vitamins to replace those lost in processing and sugar may be added at this stage. It then takes four hours and vast amounts of energy to drive the steam out of the cooked grits before they can be rolled by giant rollers into flakes.
Steamed wheat biscuits such as shredded wheats are made with whole wheat grains which are pressure cooked with water. They are then passed between rollers which squeeze them into strands and build them up into layers. These processes begin the breakdown of the raw starches in the cereals so even though they are whole grains they are absorbed more quickly in the body – and they typically have glycemic index scores of around 75, close to the GIs in the high 70s or low 80s of cornflakes, Bran Flakes, Special K and Rice Krispies, compared with 45/46 for minimally-processed grains such as porridge or mueslis without sugar. (Glucose has a GI of 100 and is what these indexes measure other foods against. They indicate how fast different foods are converted to glucose and absorbed into the bloodstream.)".
"It was when I saw details of the proposals from Ofcom on restricting marketing of junk foods to children that I understood why the lobbying had been so determined. What became clear was that breakfast cereals, although heavily marketed as healthy, would be the category to take the largest hit by a long way. About £70 million of TV ads a year from cereal manufacturers would be banned because they were promoting what the experts defined as unhealthy. The sector spent a total of £84 million on ads that year. In other words, the vast majority of its marketing effort would be wiped out. It had everything to lose. Because, as the House of Commons had been told, without marketing to manipulate our desires, we might not eat processed cereals at all."
https://www.theguardian.com/business/2010/nov/23/food-book-extract-felicity-lawrence