Folate Intake And Colorectal Cancer.

INTAKE of high levels of folate may reduce
colorectal cancer risk, according to a new
study in Gastroenterology, the official
journal of the American Gastroenterological
Association (AGA) Institute. Folate is a water-
soluble B vitamin that occurs naturally in
food.
"We found that all forms and sources of
folate were associated with lower risk of
colorectal cancer," said Victoria Stevens, PhD,
of the American Cancer Society and lead
author of this study.
"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.
A 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.
Further, one important difference between
the current study and previous studies was
the separate assessment of natural folates
and folic acid. Previous studies that
discriminated between folates considered
only the source (i.e., diet versus
supplement) and not the chemical form.
The study also addressed concerns that the
intake of high levels of folate frequently
consumed in the U.S. — as a result of the
recent increase in the use of folate-
containing supplements and mandatory
folate fortification of food — may actually
increase risk of cancer. No increased risk of
colorectal cancer was found for the highest
intake levels, suggesting that the high levels
of this vitamin consumed by significant
numbers of Americans should not lead to
increased incidence rates of this cancer in
the population.
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.