An E number tells you what a substance does in food, not what it is made from. E120 is carmine, extracted from dried cochineal insects, and the colour with the best-documented allergy reports. E904 is shellac, the resinous secretion of a scale insect, harvested with the insects still in the raw material. E920 is L-cysteine, authorised from fermentation, from chemical synthesis and from the hydrolysis of keratin from poultry feathers, with nothing on the label to say which. And E441 is not on the current approved list at all, because gelatine is regulated as an ingredient rather than as an additive.