The amino-acid composition of Crassostera gigas extract powder (JCOE, Japan clinic oyster extract) is high in glutamic acid and taurine. In order to study whether these components present in JCOE could be contributory factors in enhancing cellular glutathione-stimulating hormone (GSH) and glutathione S-transferase (GST), HL60 cells were exposed to increasing concentrations of JCOE. Statistically significant increases in GSH occurred at extract concentrations of 0.05 and 0.1% with no significant change in GST activity. Because of the high taurine levels measured in the extract, the effects of micromolar taurine supplementation of the medium were studied. A modest, but not statistically significant increase in both GSH levels and GST activity was measured. We therefore conclude that while the taurine present in JCOE could be a contributory factor in enhancing GSH and GST, it was not the only stimulus.