Confused about calcium and vitamin D?
Who isn’t? The recent media coverage on the topic of calcium and vitamin D has created a tremendous amount of confusion among not only you, but your health care providers, too. Unfortunately, this news coverage may be counterproductive to promoting adequate calcium and vitamin D intake for bone health. By thinking calcium and vitamin D are not needed, you may be jumping to the wrong conclusion.
Calcium and vitamin D are essential nutrients. Our bodies do not make calcium. We need to take in calcium each day. In contrast, we do make vitamin D. However, the production of vitamin D by the skin from sun exposure is not fail-safe. Season of year, geographic location, time of day, skin color, sunscreen, body size, age, liver or kidney problems may play havoc with the production of active vitamin D.
Recommendations
The Institute of Medicine Committee to Review Dietary Reference Intakes for Vitamin D and Calcium updated recommendations in 2010. Their recommendations for vitamin D intake are based on support for bone and muscle (musculoskeletal) health. The updated vitamin D dietary reference intakes were based on the vitamin D target blood level of 20 ng/ml.
Other recommendations on vitamin D intake have come from a variety of national and international organizations before and after the 2010 Institute of Medicine updated intakes. The recommended Institute of Medicine values work as a whole for a public health message but may not necessarily meet your individual needs. On the other hand, groups like The Endocrine Society guidelines emphasize the care of patients who are at risk for vitamin D deficiency and specify 30 ng/ml as the minimum target blood level.
Latest Recommendation is Negative
The latest recommendation on vitamin D and calcium is from the U.S. Preventive Services Task Force (USPSTF) published online in the Annals of Internal Medicine February 26, 2013. The committee’s stated goal was “to assess the effects of supplementation on bone health outcomes in community-dwelling adults, the association of vitamin D and calcium levels with bone health outcomes, and the adverse effects of supplementation.”
The USPSTF concluded with a negative recommendation: “The USPSTF recommends against daily supplementation with 400 IU or less of vitamin D3 and 1000 mg or less of calcium for the primary prevention of fractures in noninstitutionalized postmenopausal women.”
It is important to point out that this recommendation does not apply to the treatment of persons with osteoporosis or vitamin D deficiency. In addition, the USPSTF does not directly comment on high-risk seniors who are living in assisted living or skilled nursing facilities.
The USPSTF committee considered only 6 randomized trials in the community setting evaluating the use of vitamin D and calcium supplementation as primary prevention of fractures. They found calcium plus vitamin D supplements did not reduce fractures in community-dwelling persons. The results are heavily weighted by the largest trial, the Women’s Health Initiative (WHI).
In the WHI Calcium plus Vitamin D Trial over 36,000 women who were age 50 to 79 years old at the start of the study were randomly assigned to take 1000 mg of calcium with 400 IU of vitamin D daily or placebo pills. At the end of seven years, the number of fractures was similar in each group.
The WHI has been criticized that vitamin D 400 IU daily was too low a dose but that was the standard of care at the time of the study design. In 2006, after the New England Journal of Medicine published the WHI Calcium Plus Vitamin D Trial results, you may have read or heard these familiar sounding headlines:
CALCIUM PLUS VITAMIN D DID NOT PREVENT FRACTURES
CALCIUM, VITAMIN D NOT AS BENEFICIAL AS ONCE THOUGHT
CALCIUM, VITAMIN D INEFFECTIVE IN REDUCING FRACTURES
However, those headlines missed one paragraph in the WHI results. A separate analysis was done of just the women who were actually taking their assigned study pills. If they had taken their pills 80% or more of the time, their risk of hip fracture was reduced by 29%. Several months after the original publication, the WHI authors wrote in New England Journal of Medicine Letters to the Editor that they believed their data supported the recommendation for adequate calcium and vitamin D intake in postmenopausal women.
The USPSTF also evaluated 5 trials that compared vitamin D alone versus placebo or no treatment in community-dwelling (3 trials) and institutionalized settings (2 trials) and found no fracture reduction.
Of note in 2012, a different committee of the USPSTF found daily vitamin D supplementation prevented falls in community-dwelling persons age 65 and older and recommended following the 2010 Institute of Medicine guidelines. As we are well aware, falls result in broken bones in our older patients.
Is It A Dose Effect?
Another analysis examining dose of vitamin D and fractures done after the USPSTF by lead author Dr. Heike Bischoff-Ferrari and colleagues that included WHI investigators as well as investigators from other vitamin D trials was published in July 5, 2012 issue of the New England Journal of Medicine. Vitamin D supplementation of 800 IU or more daily in persons 65 years of age or older significantly reduced the risk of hip fracture by 30% and the risk of any nonspine fracture by 14%. Benefits at this level of vitamin D intake were consistent across subgroups defined by age group, type of dwelling, baseline vitamin D blood level, and additional calcium intake.
How Much?
The debate is far from settled. What is the right amount of vitamin D for calcium absorption, bone mineral density, muscle strength, and fracture reduction remains controversial.
If sunshine and food sources are not providing adequate vitamin D as observed in the majority of American, supplementation with vitamin D is recommended. To meet the recommended calcium intake of 1000 to1200 mg a day, use food first and supplement, only if needed to reach your target amount. Talk with your health care provider to sort out what you should be doing to promote your bone health with vitamin D and calcium.
Do vitamin D and calcium reduce the risk of fractures?
The news headlines are conveying the wrong message. Vitamin D and calcium ARE essential for bone health. The real question is how much is enough?
Image: Courtesy of 4BoneHealth
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Diane L. Schneider, MD, MSc
Author, The Complete Book of Bone Health
Medical Editor, 4BoneHealth.org