Health News: Top Stories 2006
[Continued from page 2]
In 2006, the headlines read...
VITAMIN D, CALCIUM AND WON'T PREVENT HIP FRACTURES
What you may have seen:
Most news reports said taking 1,000 milligrams (mg) calcium plus 400 international units (IU) vitamin D daily results in a small (one percent) improvement in hip density, but it does not significantly reduce the risk of fractures in bones, according to the Women’s Health Initiative (WHI). Instead of proving supposed health benefits, the regimen – tested in more than 36,000 women aged 50 to 79 – increased the risk of kidney stones by 17 percent.
Reaction?
Disbelief. The notion that taking calcium and vitamin D benefits bone had become widespread – ranking among the top health recommendations for women older than 60, those most at risk of osteoporosis – despite the fact that the supplements’ ability to reduce or prevent fractures had not been intensively studied. Calcium, along with regular exercise, was known to be important for keeping bones strong, and vitamin D was known to help increase calcium absorption. Strong bones are less likely to fracture during a fall. The theory seemed solid at the start, but shattered in the headlines.
Disbelief was followed by dismay. Hormone replacement therapy – once a staple preventive for fractures – is now considered off-limits for most postmenopausal women because it increased risk of breast cancer, heart attack, stroke and blood clots in the lungs and legs in an earlier portion of WHI. Now it appears that calcium and vitamin D supplements – a simple, safe, low-cost way to maintain health into old age – was ineffective and potentially troublesome.
What you might have missed:
The one-percent increase in hipbone density may be small, but it is still significant. And not all women in the treatment group followed the plan. Women who stuck to the study protocol and actually took the calcium and vitamin D twice daily as directed for the study duration were 29 percent less likely to fracture their hips than those given placebo. And among the participants, women older than 60 also had a significant 21 percent reduction in hip fractures.
Doctors and others who read the study saw a damning flaw. Because calcium’s benefit to bones was firmly assumed, researchers thought it unethical to deny calcium and vitamin D to the women in the study control group – the group that was to be compared to those taking the regimen being tested – so they were allowed to take up to 1,000 mg of calcium and up to 600 IU of vitamin D, an amount higher than used in the study. That study design problem was compounded because the participants were given unidentified pills – some placebo, some real – for the sake of keeping the study “blind.” So some of the women may have been getting doses of calcium and vitamin D on top of whatever they were taking or eating on their own.
Moreover, many of the women in the calcium and vitamin D study also had been taking estrogen as part of the hormone therapy study arm of WHI, and hormones, like estrogen, are known to strengthen bone and reduce fractures. Although the hormone therapy study was stopped halfway through the calcium and vitamin D study, the fact that more than half of the women had taken hormones that could have strengthened their bones might have made the measure of reduction in fractures between the treatment and control group closer and, thus, less significant.
Many media reports also failed to note that 37 percent of women in the study were in the 50 to 59 age group, a time of life when the incidence of fractures is much lower. Experts point out, too, that benefits of the bone-protecting regimen were most likely to be seen among women who initially had a calcium deficiency, but each woman’s calcium level was not measured before the study started.
There were more factors that made the study results less clear. The women’s average body mass index (BMI) was 29; they were overweight, but not obese. And larger people tend to have stronger bones than thin people.
“This study shows us exactly what we anticipated – that calcium plus vitamin D helps improve bone health – but the supplements are not a treatment for fracture reduction,” explains Dr. Lane. “Calcium and vitamin D are the foundation for good skeletal health. That’s why we use it. Calcium and vitamin D are not and never were intended for preventing fractures.”
Your take-home message:
The WHI recommends that postmenopausal women get 1,500 mg of calcium a day and 400 to 800 IU of vitamin D a day through a combination of diet and supplements. Dr. Lane recommends the same amount of vitamin D and at least 1,000 mg of calcium per day for men and premenopausal women.
Read what the experts have to say about these stories that that made headlines in 2006:
Headline: Glucosamine and Chondroitin Offer Little Relief for Knee Osteoarthritis Pain.
Here's what you should know about the major studies that generated headlines in 2006:
