The effect of heating on the functional activity of iota carrageenan

Iota carrageenan is toxic to cells of the reticuloendothelial system. If carrageenan is dissolved at 40 degrees C and injected intraperitoneally, it will induce a significant reduction of alveolar macrophages. Heating the carrageenan preparation to 121 degrees C, however, results in a marked diminution of this in vivo cytotoxicity. This observation offers an explanation for the variability of effects previously attributed to carrageenan, and suggests that preparation methods should be standardized and carefully monitored.