The diet of the average teenager in the UK is 66 per cent ultra processed foods, according to new research set to be discussed at the Cambridge Festival later this month. These ‘foods’ contain edible substances that you wouldn’t use in home cooking and include emulsifiers, modified starch, hydrogenated vegetable oil, chemicals, colourings, sweeteners and preservatives that extend shelf life. They are in everything from supermarket bread and ready meals, to flavoured yoghurts, sauces, crisps, biscuits, cereals, fizzy drinks, fries, ice cream, sausages, vegan meat replacements and dairy alternat…