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Release: Immediate

UI professor: Food additive may have breast cancer-causing properties

IOWA CITY, Iowa -- Lambda-carrageenan, a food additive widely used in milk products such as infant formula, pudding, ice cream and whipped cream, may have cancer-inducing properties.

A form of lambda-carrageenan has been shown to cause intestinal cancer and ulceration in animals. In addition, the food additive has been shown to cause the kind of changes in intestinal cells that lead to malignant tumors. These facts made University of Iowa College of Medicine researcher Dr. Joanne Tobacman wonder if the additive also affected breast cells in a way that might lead to cancer.

In the laboratory, Tobacman, assistant professor of internal medicine, examined the effect of the food additive on mammary myoepithelial cells she grew in tissue culture. She found that lambda-carrageenan exposure caused destruction of the cells and eventual cell death. This finding was reported in the July issue of the journal Cancer Research.

One of the most important points of her study, Tobacman says, is that lambda-carrageenan caused myoepithelial cell death at concentrations far below those normally found in food products. The finding is potentially significant.

"The mammary myoepithelial cells form a barrier between the blood supply and epithelial cells. Compromise of this barrier may lead to the development of malignant or invasive tumors," Tobacman says.

In fact, most malignant tumors arise from epithelial cells, and myoepithelial cell absence is used as one criterion for the diagnosis of an invasive malignancy.

Do these findings mean that lambda-carrageenan, which has been on the market since 1937, is a cancer-causing food additive?

"We can't say that, yet," Tobacman says. "We have taken one step forward and found an interesting association. Having new territory to explore with regard to environmental agents that may be "smoking guns" with regard to breast cancer is good news to cancer epidemiologists who have been looking for an environmental etiology for breast cancer."

Tobacman would like to find out more precisely how lambda-carrageenan affects the breast myoepithelial cells. She is seeking funding for further studies and would like to bolster the laboratory findings with epidemiological evidence, though it is difficult to quantify the intake of carrageenan. She and other investigators are reviewing the diet questionnaires filled out in 1986 by more than 50,000 women involved in the Iowa Women's Health Study, in order to obtain more information about carrageenan intake.