High intake of vitamin E appears to prevent liver cancer, Chinese scholars find. Xiao-Ou Shu, MD, PhD, of the Vanderbilt University Center for Epidemiology in Nashville, and colleagues published an article online in the Journal of the National Cancer Institute, saying that a high intake of vitamins in the diet of people aged 40-70 years significantly reduced the risk of cancer (P=0.01 for trend test), and that vitamin E supplements reduced the risk by almost half (HR 0.52, 95% CI 0.30 to 0.90). The researchers believe that if the findings are confirmed, these findings could potentially open up a new battleground for cancer prevention. Because the link between dietary factors and vitamin supplementation and liver cancer development is unclear, Shu and colleagues evaluated data from a study of 132,837 patients collected from the Shanghai Women’s Health Study and the Shanghai Men’s Health Study. The investigators used a food frequency questionnaire to assess vitamin intake in the diet and dietary supplements. During the follow-up phase, 267 patients developed liver cancer, with a mean time to liver cancer development of 10.9 years in women and 5.5 years in men. The researchers found that high levels of dietary vitamin E intake reduced the risk of liver cancer, with the two highest dose groups in the quartile having a significantly lower risk of liver cancer (HR 0.66, 95% CI 0.46 to 0.94 and HR 0.60, 95% CI 0.40 to 0.89, respectively; P=0.01 for trend test). Taking vitamin E supplements reduced the risk of liver cancer by almost half compared to those who did not use vitamin E supplements (HR 0.52, 95% CI 0.30-0.90). Further analysis showed that the association was stronger in the female subjects. The researchers noted that the findings remained consistent among patients with or without liver disease, with or without a family history of liver cancer. The potential preventive effects of vitamins may be related to their ability to prevent DNA damage, enhance DNA repair, prevent lipid peroxidation, inhibit activation of carcinogens or enhance the function of the immune system. As for other types of vitamins, researchers found that vitamin C appeared to increase the risk of liver cancer (HR 1.96, 95% CI 1.29 to 2.98) and multivitamins increased the risk of liver cancer in men (HR 1.84, 95% CI 1.13 to 2.98). However, concomitant use of vitamin C and E supplements increased the risk of liver cancer in those with a history of liver disease and a family history of liver cancer (P values 0.01 and 0.06, respectively). Shu and his colleagues also noted that dietary intake of vitamin C and other vitamins did not increase the incidence of liver cancer. There was also no correlation between the use of vitamin B or calcium supplements and the risk of liver cancer. Shortcomings of the study include the relatively short follow-up period, the reliance on food frequency questionnaires to evaluate dietary intake, the lack of information on specific doses of vitamin intake, and the inability to exclude unmeasured confounding factors such as hepatitis B and C and other risk factors. The investigators suggest that vitamin E may play an important role in the prevention of liver cancer in Chinese patients.