I dont know where nickel comes in here, but if I get your drift, nickel impair histidine. Like polysorbate 80
"Histamine also stimulates the secretion of the digestive enzyme gastrin. Without adequate histamine production healthy digestion can become impaired. Without adequate L-histidine stores, the body cannot maintain adequate histamine levels."
And allergy follows..
"Polysorbate 80 is a nonionic surfactant and emulsifier derived from polyethoxylated sorbitan and oleic acid. It is used as an emulsifier in foods, particularly in ice cream. Adding this substance prevents milk proteins from completely coating the fat droplets. It is an excipient that is used to stabilize aqueous formulations of medications for parenteral administration, and used as an emulsifier in the manufacture of the popular anti-arrhythmic amiodarone" http://www.worldofchemicals.com/wochem/pub/chempolysorbate-80.html
ok, now we are talking allergy, children, milk, ice cream.
I scream.