Milk hypersensitivity – key to poorly defined gastrointestinal symptoms in adults

Lactose intolerance is a common adverse reaction to milk in adults, while milk hypersensitivity is a disorder of infancy. We hypothesized that milk hypersensitivity may cause many unspecific gastrointestinal disorders in adults. Twenty adults were subjected to double‐blind, placebo‐controlled milk challenge. Phagocyte activity, and Fc γ and complement receptor expression of phagocytes were assayed, and serum total IgE. milk‐specific IgE, and serum reactivity to milk protein were determined. The challenge increased phagocyte activity and complement receptor expression of phagocytes in subjects designated miUc‐hypersensitive, who had gastrointestinal symptoms from milk ingestion but normal lactose tolerance. The increase was not detected in lactose‐intolerant or control subjects. The milk‐hypersensitive group was also distinguished from the lactose‐intolerant group by enhanced serum reactivity to milk protein. Only two out of nine milk‐hypersensitive subjects had detectable milk‐specific serum IgE. It is concluded that milk hypersensitivity in adults, occurring as gastrointestinal reactions, may be more common than previously thought.