THURSDAY, June 27 (HealthDay News) -- Regularly eating oily fish
such as salmon, tuna or sardines may help reduce the risk of breast
cancer, a new report suggests.
These fish contain a type of fatty acid known as n-3
polyunsaturated fatty acids (PUFAs).
"Increased n-3 PUFA intake has a protective effect for breast
cancer," said researcher Duo Li, a professor of nutrition at
Zhejiang University in Hangzhou, China.
Li and his team reviewed 21 different studies that looked at the
intake of fish and PUFAs. The previously published research
included more than 800,000 women in the United States, Europe and
Asia, and 20,000 cases of breast cancer. The follow-up time varied,
from four years to 20.
The new report is published online June 27 in the journal
Fish include several types of PUFAs that are involved in
chemical messaging in the brain, helping to regulate both blood
vessel activity and the immune system. The fatty acids also have
been linked with other health benefits, such as lower risk of heart
Earlier studies have shown conflicting results about the
protective effects of PUFAs that are found in fish and breast
cancer risk. So Li decided to pool the results of the 21 studies
and reanalyze them.
In his analysis, consumption of most types of PUFAs -- but not
fish itself -- was linked with a lower risk. Women with a high
intake of PUFAs had a 14 percent reduction in breast cancer risk.
For every 0.1-gram-per-day increase in the intake of the fatty
acids, there was a 5 percent lower risk of breast cancer, the study
So how much fish should you eat? "One to two servings of oily
fish per person per week is suggested," Li said.
Li said he can't explain with certainty the association between
PUFAs and lowered breast cancer risk. Among other possibilities, he
speculated that the fatty acids may help regulate the activities of
molecules involved in cell growth and in the spread of cancer
Two U.S. experts who reviewed the new findings saw pros and cons
to the report.
Although the number of women studied was large, the link found
between fatty acid intake and breast cancer risk reduction "is not
necessarily cause-and-effect," said Dr. Stephanie Bernik, chief of
surgical oncology at Lenox Hill Hospital in New York City.
Dr. Joanne Mortimer, director of women's cancer programs at the
City of Hope Comprehensive Cancer Center in Duarte, Calif., agreed.
"My take on this is it may be more than just what they eat" that
helps reduce breast cancer risk, she said. "To make an assumption
that the lower risk is due entirely to diet may be a false
The women with a high intake of PUFAs also may be more apt to
exercise and follow other healthy habits, Mortimer said.
Both Mortimer and Bernik cautioned against focusing too much on
fish for risk reduction or on eating too much of it. "It's no
cure-all," Bernik said. And, if eaten in excess, the mercury
content of some fish can be unhealthy, she added.
Besides eating oily fish, Bernik tells patients to exercise
regularly, eat plenty of fruits and vegetables, and not smoke to
reduce the risk of breast and other cancers.
To learn more about breast cancer risks, visit the
American Cancer Society.