WASHINGTON - Intake of high levels of folate, a water-soluble B vitamin that occurs naturally in food, may reduce colorectal cancer risk, according to a new study published Tuesday in Gastroenterology, the official journal of the American Gastroenterological Association (AGA) Institute.

"We found that all forms and sources of folate were associated with lower risk of colorectal cancer," said lead author Victoria Stevens, of the American Cancer Society. "The strongest association was with total folate, which suggests that total folate intake is the best measure to define exposure to this nutrient because it encompasses all forms and sources."

Total folate includes naturally occurring food folate and folic acid from fortified foods and dietary supplements.

The research team investigated the association between folate intake and colorectal cancer among 99,523 participants in the Cancer Prevention Study II Nutrition Cohort; a total of 1,023 participants were diagnosed with colorectal cancer between 1999 and 2007, a period entirely after folate fortification began. Neither higher nor lower risk was observed during the first two years of follow-up (1999 to 2001), while associations were statistically significantly inverse for the subsequent years (2002 to 2007). The findings of this study add to the epidemiologic evidence that high folate intake reduces colorectal cancer incidence.

Folates are essential nutrients needed to make components used for functions required for normal cell growth, including DNA synthesis and repair. Because these processes are critical for cell growth and differentiation, the relationship between folate intake and cancer development has been investigated in several cancers, and most extensively in colorectal cancer.