High consumption of vitamin E either from diet or vitamin supplements may lower the risk of liver cancer, according to a study published July 17 in the Journal of the National Cancer Institute.
Liver cancer is the third most common cause of cancer mortality in the world, the fifth most common cancer found in men and the seventh most common in women. Approximately 85% of liver cancers occur in developing nations, with 54% in China alone. Some epidemiological studies have been done to examine the relationship between vitamin E intake and liver cancer; however, the results have been inconsistent.
To determine the relationship between vitamin E intake and liver cancer risk, Wei Zhang, MD, MPH., of the Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine and colleagues analyzed data from a total of 132,837 individuals in China who were enrolled in the Shanghai Women's Health Study (SWHS) from 1997-2000 or the Shanghai Men's Health Study (SMHS) from 2002-2006, two population-based cohort studies jointly conducted by the Shanghai Cancer Institute and Vanderbilt University. Using validated food-frequency questionnaires, the researchers conducted in-person interviews to gather data on study participants' dietary habits. They compared liver cancer risk among participants who had high intake of vitamin E with those with low intake.
The analysis included 267 liver cancer patients (118 women and 149 men) who were diagnosed between 2 years after study enrollment and an average of 10.9 (SWHS) or 5.5 (SMHS) years of follow-up. Vitamin E intake from diet and vitamin E supplement use were both associated with a lower risk of liver cancer. This association was consistent among participants with and without self-reported liver disease or a family history of liver cancer. "We found a clear, inverse dose-response relation between vitamin E intake and liver cancer risk," the authors write, noting a small difference between men and women in the risk estimate, which is likely attributable to fewer liver cancer cases having occurred among SMHS participants due to the shorter follow-up period. Overall, the take home message is that, "high intake of vitamin E either from diet or supplements was related to lower risk of liver cancer in middle-aged or older people from China."
Xiao-Ou Shu, MD, PhD, Xiao-Ou.Shu@Vanderbilt.edu
Yong-Bing Xiang, MD, MPH, firstname.lastname@example.org