Back story. When he was 3 he got cdiff (an infection of the gut caused by the bacteria Clostridium difficile, often after antibiotics). It cleared but he would still have bloody mucus stools and to a point literally just pass a bit of blood and mucus. No stool. He went into growth retention. Blood tests, cdiff tests all came back in range.  When he was 18 months he had Goldfish (a type of biscuit containing annatto) and broke out into hives. At school he had Cheez-its (a cheese cracker containing annatto). Broke out into hives.  The only common ingredient was annatto.  During the same period he developed alopecia. I talked with his gastro and he said take him off all annatto give it three weeks and see what happens.  His hair grew back, he gained 10 lbs and has had normal stool since!  He is 8 now.  It's not all a coincidence. I know in my mama gut annatto is evil.  This is his story – Angela from USA (italics added)

See also Alopecia factsheet