Eating plenty of folate may sharply reduce the risk of colorectal cancer, at least for women, South Korean researchers report.
In a study of 596 colorectal cancer patients and 509 healthy individuals, they found that the women who ate the most folate were at about two-thirds lower risk of the disease than women who consumed the smallest amount of the B vitamin.
But folate intake didn't significantly affect men's colorectal cancer risk, Dr. J. Kim of the National Cancer Center in Goyang and colleagues report.
Deaths from colorectal cancer have jumped more than six-fold among South Koreans since the early 1980s, the researchers note, and an increasingly Western-style diet may be a factor in the increase.
There is evidence that intake of folate, which is found in green, leafy vegetables and citrus fruits, may reduce colorectal cancer risk, although some research suggests this protective effect could vary by ethnic background.
To look at the relationship in a Korean population, the researchers compared the diets of colorectal cancer patients and healthy controls matched by age and gender. The cancer patients drank and smoked more, were less active, and were also more likely to have a family history of the disease.
The researchers looked at the influence of dietary folate intake on disease risk after using statistical techniques to control for these factors, and found that people in the top fifth based on their folate intake (consuming more than 270 micrograms a day) were more than half as likely to have cancer compared to people in the bottom fifth, who ate 180 micrograms or less daily.
When Kim and colleagues looked at men and women separately, they found no influence of folate intake on mens' colorectal cancer risk. But women with high folate consumption (over 300 micrograms a day) were 64 percent less likely to develop colorectal cancer compared to women with the lowest consumption (200 micrograms daily or less).
The findings are important, the researchers note, because they suggest that cancer risk can be decreased by modifying diet.
The body needs folate in order to form nucleotides (the building blocks of DNA and RNA), to copy DNA, and for other essential genetic functions, so low folate intake could contribute