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Vitamin D fails to improve bone density
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Oral vitamin D doses made no impact on patients’ bone mineral density during a 12-month period in patients aged 70 years and older, according to findings recently published in American Journal of Clinical Nutrition.
“Previous study findings are conflicting, which may reflect variations in study design, the characteristics of participants (such as age, frailty and baseline vitamin D status), and the nature of intervention, including vitamin D dose, its route, the frequency of administration, and the form of vitamin D (whether vitamin D2 or vitamin D3),” Terry J. Aspray, NIHR, of the Newcastle Biomedical Research Center, Newcastle Upon Tyne, England, and colleagues wrote.
Researchers randomly provided 379 adults (mean age, 75 years; 48%, women; baseline plasma 25-hydroxyvitamin D, 40 nmol/L) living in England with 12,000 IU, 24,000 IU or 48,000 IU orally once a month for 1 year. Participants were excluded if they previously or currently had hypercalcemia, hypocalcemia, adjusted plasma calcium and/or an estimated glomerular filtration rate of less than 30 mL/minute/1.73 m2; were treated with anabolics or antiresorptives in the previous 3 years, consumed more than 500 mg of vitamin D a day, had a fragility fracture in the previous 6 months and/or prior history of bilateral hip replacements, primary hyperparathyroidism, or renal stones.
Aspray and colleagues found the mean plasma 25-hydroxyvitamin D concentration level increased to 55.9 nmol/L, 64.6 nmol/L and 79 nmol/L for participants in the 12,000 IU, 24,000 IU and 48,000 IU groups, respectively. However, dual-energy X-ray absorptiometry of the patients’ bone mineral density at the hip showed no between-group differences.
“It is possible that all 3 doses attenuated an anticipated decrease in [bone mineral density] of 0.6% over this period because we had no placebo comparator. An alternative explanation for studies showing a positive effect of vitamin D on bone mineral density may be the treatment of an undetected osteomalacia, which would result in an increase in bone mineral density,” researchers wrote. – by Janel Miller
Disclosures: Healio Primary Care Today was unable to determine authors’ relevant financial disclosures prior to publication.
Perspective
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Liz Weinandy, MPH, RD
Aspray and colleagues’ results are not surprising. Other studies have shown mixed results with vitamin D supplementation. Consequently, there are studies that show benefits and others like this one that show little to no benefit.
One of the limitations of this study is that vitamin D is only one piece of the bone health puzzle. There are many other nutrients important for bone health, including magnesium, calcium and phosphorus. Therefore, supplementing vitamin D only may not help increase bone density without these other nutrients. The other thing to consider is that vitamin D also has a powerful effect on the immune system, providing more incentive for older patients to keep consuming it.
Most Americans likely need vitamin D supplementation. This is especially true for patients who live north of the longitudinal line that parallels the city of Atlanta, since these patients are most at risk for not getting enough vitamin D from sunlight exposure.
Therefore, primary care physicians should still encourage their patients aged 70 and older to consume the recommended daily allowance of 800 IU of vitamin D. For strong bones, people should also consider adding other foods and/or supplements in their diet like magnesium and calcium. The recommended daily amount of magnesium is 420 mg for men and 320 mg for women. The great majority of Americans do not meet their needs for this nutrient in particular. Calcium and phosphorus are other nutrients to consider, although most Americans meet their needs for phosphorus. Since these minerals work together to maintain bone health, we need to consider all of these. Other considerations include limiting sodium and large amounts of protein since both of these can pull calcium out of the blood and thin bones over time.
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