Calcium and vitamin D in osteoporosis
supplementing their diet with calcium and vitamin D, known to help build
strong bones, many women believe they will be protected from the fractures
that often occur as bones become more porous with osteoporosis. Is that a
valid assumption ?
A study randomly assigned 36,282 post-menopausal women, who averaged 62
years old, to take a combination of calcium ( 1,000 mg ) and vitamin D
( 400 IU ) or a placebo daily.
After about seven years, women who took the supplements had retained
about 1% more density in their bones than had those in the placebo group.
There was little difference between the groups in the rate at which broken
bones had occurred. Kidney stones were more common among women who took
calcium and vitamin D, as were constipation and bloating or gas.
Who may be affected by these findings ? Post-menopausal women, who can
lose 20% of their bone mass within seven years of menopause, increasing
their susceptibility to osteoporosis. About 1½ million broken bones a
year are attributable to the disease, which afflicts 20 million Americans,
80% of them women.
Caveats: Slightly more than half of the women in the study also took
hormone therapy, which may have affected the results. The study did not
differentiate between the effects of calcium and vitamin D. About 41% of the
participants were not taking the specified dosages at the end of the study.
At the start of the study, participants did not have vitamin D or
calcium deficiency; whether people with such deficiency should expect the
same results remains unclear. Earlier studies, which yielded more positive
results, involved higher doses ( 600 IU ) of vitamin D.