(RxWiki News) If you're researching how vitamins, minerals and antioxidants affect your cancer risk, good luck getting a straight answer. A new study shows vitamin E may be your friend and vitamin C may be your foe.
A large study conducted in China assessed a link between high vitamin E intake - both through foods and supplements - and a lower risk of liver cancer.
The same research found that high vitamin C consumption and multivitamin use produced the opposite results by increasing the risks of liver cancer slightly.
"Eat your spinach."
Researchers, led by Wei Zhang, MD, MPH, of the Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine, analyzed information pertaining to nearly 133,000 people.
These individuals were enrolled in one of two studies - the Shanghai Women's Health Study (SWHS) from 1997 - 2000 or the Shanghai Men's Health Study (SMHS) from 2002-2006 - which were a joint undertaking of the Shanghai Cancer Institute and Vanderbilt University.
Researchers used validated food surveys and in-person interviews to study individual dietary habits.
A total of 267 individuals were diagnosed with liver cancer between 2 years after the study enrollment and the follow-up years, that ranged from 5.5 years for men and 10.9 years for women.
They found that people who consumed a high amount of vitamin E in food and supplements had lower liver cancer risks than people who consumed low amounts of the vitamin. This was seen throughout the groups, including folks with and without a family history of liver disease/cancer.
"We found a clear, inverse dose-response relation between vitamin E intake and liver cancer risk," the authors write.
There was a difference in these rates among men, which the researchers attribute to the shorter follow-up time.
The authors concluded, "Therefore, our study provides strong evidence suggesting that vitamin E intake, either from dietary sources or supplements, reduces the risk of liver cancer."
The opposite relationship was seen with vitamin C and multivitamin supplements.
"On the other hand, use of vitamin C and multivitamin supplements in men was statistically significantly associated with an increased risk of liver cancer among individuals with self-reported liver disease or family history of liver cancer," the authors wrote. This association was strongest in men who were smokers.
"Similarly, we found that multivitamin supplement use was associated with increased risk of liver cancer in men," the authors reported.
This study was published July 17 in the Journal of the National Cancer Institute.
The research was supported by the National Institutes of Health and the funding of the State Key Project Specialized for Infectious Diseases of China.