Iodine as a trace element is an essential nutrient for human growth and development. Its potential impact on manpower development in third world countries are of special concern, primarily due to iodine deficiency disorders (IDD) such as goiter, hypothyroidism, and cretinism. IDD of mild to moderate severity are still found in Malaysia. The prevalence ranges from almost zero in many developed urban areas to more than 90% in some rural parts of Malaysia, especially in Sabah and Sarawak. The endemias were associated with low urinary excretion of iodine among the population, indicating poor iodine intake and low iodine content in the environment. Water and salt iodination strategies are being planned to eradicate the disease by the year 2000.
The effects of long-term administration of tocotrienol on hepatocarcinogenesis in rats induced by diethylnitrosamine (DEN) and 2-acetylaminofluorene (AAF) were investigated by determining the activities of gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), glutathione S-transferases (GSTs), and glutathione (GSH) levels in blood and liver. Twenty-eight male 7- to 8-wk-old Rattus norwegicus rats, weighing 120-160 g, were used in this study. The rats were divided into four treatment groups: a control group on a basal diet, a group fed a basal diet supplemented with tocotrienol (30 mg/kg food), a group treated with DEN/AAF, and a group treated with DEN/AAF and fed a diet supplemented with tocotrienol (30 mg/kg food). Blood was collected monthly, and GGT, ALP, and GSH levels were determined. The rats were killed after 9 mo, and the livers were examined morphologically. Grayish white nodules (2/liver) were found in all the DEN/AAF-treated rats (n = 10), but only one of the rats treated with DEN/AAF and supplemented with tocotrienol (n = 6) had liver nodules. A significant increase in the level of blood and liver GSH, ALP, and GGT activities was observed in the DEN/AAF-treated rats. Liver GSTs were similarly increased with DEN/AAF treatment. Tocotrienol supplementation attenuated the impact of the carcinogens in the rats.