Vitamin B6 Cuts Colon Cancer Risk

Roman Bystrianyk · medicine forum Guru Joined: 02 May 2005 Posts: 454

http://www.healthsentinel.com/news.php?event=news_print_list_item&id=793

Kathleen Doheny, "Vitamin B6 Cuts Colon Cancer Risk", Forbes, May 4,
2005,
Link:
http://www.forbes.com/lifestyle/health/feeds/hscout/2005/05/04/hscout525506.html

High daily levels of vitamin B6 may reduce the risk of getting colon
cancer by 58 percent, claims a new study from Harvard Medical School.

The research, published in the May 4 issue of the Journal of the
National Cancer Institute, builds on other studies that have already
indicated a strong preventive effect from the vitamin.

"There are several smaller studies that have found a protective effect
from dietary intakes of B6," said lead researcher Esther K. Wei, an
instructor in medicine at Harvard Medical School and Brigham and
Women's Hospital. However, "this is the first large study of women to
look at blood levels of B6" and find a protective effect, she added.

Wei and her colleagues evaluated nearly 33,000 women who were
participants in the Nurses' Health study, a long-running study that
began in 1976. Since then, researchers have focused on subsets of the
original 121,700 participants, all nurses between 30 and 55 years of
age when they enrolled, to study various health issues.

Among this subset, Wei and her team analyzed blood samples collected in
1989, looking for levels of a substance called PLP (pyridoxal
5'-phosphate) -- the main active form of vitamin B6 in the blood. Then
they looked at medical records to determine who contracted cancer of
the colon or cancer of the colon and rectum (colorectal).

They found a total of 194 colorectal cancer cases and 410 cases of
colon polyps, which often precede colorectal cancer. After dividing the
women into four groups, from lowest to highest blood levels of PLP, the
researchers found that the highest quartile group had a 44 percent
lower risk of colorectal cancer and a 58 percent lower risk of colon
cancer. The same associations held for the development of polyps.

The associations between high blood levels and lower risk held even
after Wei's group controlled for other colon cancer risk factors, such
as family history of the disease.

Women in the group with the highest blood levels of B6 had about six
times the blood levels of the nutrient as those in the lowest group,
Wei said.

Dietary intake of Vitamin B6 was also associated with reduced risk.
Women in the lowest intake group got a median of 1.6 milligrams a day
compared to 8.6 milligrams in the highest intake group. The recommended
daily intake of B6 for most adults varies from 1.3 to 1.7 milligrams a
day, depending on age and gender. Those in the lowest group were
getting close to the recommended amount of daily B6, Wei said, while
those in the highest group, which got the most protective effect from
colon cancer, were getting about five times the recommended daily
intake, but still at a safe level, she said.

According to the Institute of Medicine, 100 milligrams per day of B6 is
the upper threshold of a safe intake level.

It's possible, said Wei, to take in 8.6 milligrams of Vitamin B6 a day
by taking a multivitamin and eating vitamin B6-rich food. But she
stressed that "you don't have to take in 8.6 milligrams a day to get a
reduced risk," since reductions in cancer risk started showing up at
levels of just 3.3 milligrams a day.

Vitamin B6 is involved in around 100 physiologic reactions and
functions in the body, according to Wei, including protein metabolism,
red blood cell function and proper functioning of the nervous and
immune systems.

The vitamin can be sourced from multivitamins, fortified cereals,
beans, meat, poultry, fish and some vegetables and fruits.

Scientists aren't sure why high blood levels of vitamin B6 protect
against colon and colorectal cancer, Wei said, but she noted that
"individuals who have high levels of B6 have less chance of having
damaged DNA, which can lead to cancer."

Dr. Durado Brooks, director of colorectal cancer for the American
Cancer Society, called the new study "interesting work." If the finding
about blood levels of the vitamin and reduced cancer risk is
replicated, he said, "it will be a useful bit of information to give
people about lowering their risk of colon cancer."

Meanwhile, there are a number of measures people can take to lower
risk, he said. "Multiple vitamins with folate have been previously
shown to reduce risk." Keeping a healthy body weight and maintaining an
exercise program can reduce risk, too, he said. For those at average
risk of colon cancer, the Cancer Society recommends formal screening
beginning at age 50.

The screening tests include a fecal occult blood test, barium enema or
examinations of the colon via a test called a sigmoidoscopy or a
colonoscopy.

Colorectal cancer is the third most common cancer in the United States,
according to the American Cancer Society. The Society estimates that
104,950 new cases of colon cancer and 40,340 new cases of rectal cancer
will be diagnosed in 2005, with about 56,290 deaths linked to the
disease. The death rate from colorectal cancer has been declining,
however, probably because of early detection and improved treatments.

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