June 5, 2006
Calcium pills no help against breast cancer: study
By Lisa Richwine
ATLANTA (Reuters) - Taking calcium and vitamin D
supplements does not reduce the chances of developing breast
cancer in a U.S. study of women's health, according to findings
released on Monday, but some women may benefit and more study
was needed to confirm the findings.
"We can't yet make a general recommendation about how much
calcium and vitamin D individuals should take each day as
supplements," said Dr. Rowan Chlebowski, the study's lead
One nutrition expert said the new results were unreliable,
in part because women were allowed to take supplements besides
what they were given as part of the study.
Earlier research had suggested that vitamin D and calcium
supplements may protect women from breast cancer, which is
expected to kill about 41,000 U.S. women this year.
The findings came from a look at 36,282 U.S.
post-menopausal women in the long-term Women's Health
Chlebowski, a cancer specialist at the Los Angeles
Biomedical Research Institute at Harbor-UCLA Medical Center,
and his team measured breast cancer incidence among 18,176
women randomly assigned to take 1000 milligrams of calcium
carbonate and 400 international units of vitamin D daily. They
compared the cases to another group of 18,106 who got placebo
After about seven years, breast cancer incidence did not
differ significantly between the two groups overall. About 3
percent of women in each group were diagnosed with the disease.
Breast cancer patients in the calcium and vitamin D group
did have smaller tumors, the study found.
For one set of women, breast cancer risk was reduced. Women
who did not report any supplement use at the time they entered
the study had an 18 percent lower risk of breast cancer if they
took vitamin D and calcium during the study, compared with
others who had no prior supplement use but took placebos.
Dr. Walter Willett, an epidemiologist and nutritionist at
Harvard, said the study was flawed because all of the women
were allowed to continue personal use of calcium and vitamin D
supplements besides those provided in the study.
"I think it's uninterpretable," he said.
Sixty-nine percent of women in the study said they took
calcium supplements on their own, and about 30 percent took
multi-vitamins containing vitamin D, he said.
The women also may have been consuming calcium in milk or
other foods in which it is added.
The findings of the study, which is ongoing, were presented
at the annual meeting of the American Society of Clinical
Natural sources of vitamin D, which also helps to prevent
fractures, include sun exposure and oily fish, but most people
do not get enough from those sources, experts say.
The Institute of Medicine advises most adults to get at
least 400 international units per day, and 600 international
units for people 70 and older.