According to the Observer, four ingredients have been added to bread by law since WW2 – niacin, thiamine, iron and calcium.
(There is now a campaign underway to have folic acid added to bread in the UK. The FSA (Food Standards Agency) is going to advise the Department of Health to introduce the mandatory fortification of white and brown flour, but to exempt wholemeal flour. In America a wide range of products have to include set amounts of the vitamin - bread, corn meals, rice, noodles, macaroni and other grain products. A total of 39 countries now add folic acid to flour, including Canada, Israel and Mexico. The Republic of Ireland, Australia and Canada are considering doing the same. But, folic acid is found naturally in green leafy vegetables such as spinach and broccoli. So, just eat your greens. )