Ultra-processed foods (UPFs) are a leading cause of a "chronic disease pandemic" linked to worsening diets, experts have warned. UPFs include items such as processed meats, some ready meals and cereals, ice cream, crisps, biscuits, mass-produced bread and fizzy drinks. They often contain a high level of saturated fat, salt and sugar - as well as additives such as sweeteners and preservatives. UPFs leave less room for more nutritious foods and are also believed to negatively affect gut health.