Vitamin D, Calcium vs. Breast Cancer
Study Shows Vitamin D and Calcium in Diet May Lower Breast Cancer Risk
May 29, 2007 -- There is growing evidence linking vitamin D and calcium in
the diet to a reduced risk of breast cancer, but the benefits may be limited to
In a new study from Brigham and Women's Hospital and Harvard Medical School
in Boston, a high intake of calcium and vitamin D through food sources and
nutritional supplements was linked to modestly lower risk of breast cancer in
The link appeared strongest for the most aggressive tumors, and it was not
seen after menopause.
Researcher Jennifer Lin, PhD, says older women are more likely to be
deficient in calcium and vitamin D, so they may need higher levels of the
nutrients than were measured in the study.
"Calcium and vitamin D are important for overall health and,
additionally, they may help prevent breast cancer," she tells WebMD.
Evidence 'Fairly Consistent'
Roughly 31,000 women enrolled in the larger Women's Health Study were
included in the analysis by Lin and colleagues. The findings were published May
28 in the Archives of Internal Medicine.
All of the women were aged 45 or older, and two-thirds were
postmenopausal. The women completed questionnaires at study entry and
periodically after that were designed to determine their medical history and
lifestyle, including the foods they ate and supplements they took.
Over an average of 10 years of follow-up, 276 premenopausal and 743
postmenopausal study participants developed breast cancer.
Premenopausal women with the highest intakes of calcium and vitamin D had
modestly reduced risk of breast cancer compared with women who got the lowest
amount of the nutrients through food and supplemental sources.
The findings are similar to those reported in 2002 by another group of
Harvard researchers. In that study, calcium and vitamin D through dairy sources
were associated with a decreased risk of breast cancer before, but not after,
Dietary calcium and vitamin D were found to lower breast cancer risk in a
cancer prevention study reported by researchers from the American Cancer
ACS nutritional epidemiologist Marji McCullough, ScD, RD, who reported the
findings, tells WebMD that more study is needed to understand how vitamin D and
calcium influence breast cancer risk.
"The evidence of a modest protective benefit [for dietary vitamin D and
calcium] is fairly consistent, but we still don't know if premenopausal and
postmenopausal women benefit equally," she says.
What About the Sun
Current dietary recommendations call for people aged 50 and under to consume
just 200 international units (IU) of vitamin D a day, with 400 IU recommended
for those between the ages of 51 and 70, and 600 IU recommended after age
Many experts now agree that these levels are too low. Longtime vitamin D
researcher Cedric Garland, DrPH, says most people should get between 1,000 IU
to 1,500 IU a day.