Research at the Australian science institute, CSIRO, has shown that antioxidants in green tea can lower cholesterol in rabbits by increasing the quantity of a liver protein that works to clear cholesterol from the blood. Senior Research Scientist Dr Paul Roach says that green tea's high concentration of strong antioxidants called catechins increase the liver's LDL receptors, a major mechanism for cholesterol control. In turn these receptors work to decrease LDL, the so-called "bad cholesterol" in the blood. Catechins are a type of polyphenol, a class of antioxidant and the main constituent of green tea. Black tea contains much lower levels of catechins because they are oxidised during processing. The results of the rabbit study confirm previous CSIRO findings that green tea catechins increased the amount of LDL receptors in cultured human liver cells. Both studies were undertaken at the University of Adelaide's Physiology Department. Studies by other researchers suggest that humans could lower cholesterol levels by up to 10 per cent if they habitually consumed between 5 to 10 cups of green tea daily.