The salmon that went moo.

An odd, life-threatening allergic reaction sent a young Dutch woman into the hospital 13 months ago. Though the patient was allergic to dairy products, her episode had been triggered by a slice of bread topped with fresh salmon. Researchers in the Netherlands now report finding something very fishy about the salmon the woman ate--a taint of milk.

The woman insisted she hadn't eaten dairy products, and tests confirmed that she wasn't sensitive to fish. So chemist Stef J. Koppelman of the TNO Nutrition and Food Research Institute in Zeist began analyzing the salmon--and turned up casein, a milk protein. Upon questioning, the company that marketed the vacuum-packed fish explained that it used casein to glue together pieces of salmon into seamless steaks.

Food processors often restructure scraps of a high-value meat into products that resemble a fresh steak or similar butcher's cuts. Koppelman says that because the product looked so natural and carried no indication that it was restructured, consumers "had no reason to look for a list of ingredients. That was the real problem here." His team reports finding casein in the binder in the Dec. 18/25, 1999 LANCET.

The protein chemist says that his laboratory has "contacted all manufacturers of this kind of product in the Netherlands, and they have agreed to proper labeling." He worries that elsewhere, however, unlabeled, casein-treated fish may continue to pose a risk to people with milk allergies.