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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #146582
Title: POSITIVE ASSOCIATION BETWEEN 25-HYDROXYVITAMIN D LEVELS AND BONE MINERAL DENSITY: A POPULATION-BASED STUDY OF YOUNGER AND OLDER US ADULTS

Author
item BISCHOFF, HEIKE - BRIGHAM ARTHRITIS CTR,BOS
item DIETRICH, THOMAS - CHARITE, BERLIN, GERMANY
item ORAV, E - BRIGHAM & WOMEN'S
item DAWSON-HUGHES, BESS - HNRCA

Submitted to: American Journal of Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2003
Publication Date: 5/1/2004
Citation: Bischoff, H.A., Dietrich, T., Orav, E.J., Dawson-Hughes, B. 2004. Positive association between 25-hydroxyvitamin D levels and bone mineral density: a population-based study of younger and older US adults. American Journal of Medicine 2004;116:634-9.

Interpretive Summary: Vitamin D is essential for good bone health and low levels of vitamin D [25(OH)D] are associated with increased risk of hip fracture. Bone mineral density (BMD) is used to define peak bone mass in young adults and it is the strongest available measurement to predict fractures in the elderly. The aim of this study is to define a level of 25(OH)D necessary for the greatest growth of bone mass in young people and preservation of BMD in older adults. A representative sample of the US population was included in this study. Of the 13,432 individuals studied, 45% were White, 28% were Black, and 27% were Mexican-Americans. In all ethnic, sex, and age groups, BMD increased continuously with higher 25(OH)D levels throughout the reference range. In young Caucasians, BMD continued to rise with increasing 25(OH)D beyond the upper end of the reference range. Since BMD is generally stable in men and women aged 20 to 40 years, this suggests that higher levels of 25(OH)D may contribute to the development of higher peak bone mass. This study also confirms that Black subjects are at increased risk for low vitamin D levels when compared to Whites; however, there are low levels of 25(OH)D in all three groups. In conclusion, the 25(OH)D needed for optimal bone health may be higher than has been recognized previously.

Technical Abstract: Increased vitamin D intake is usually targeted to the elderly population for optimal bone growth and preservation. In this study, a cross-sectional, representative sample of the US non-institutionalized population was used (NHANES III; 13,432 adults between 20-90+ years) to determine whether there is an association between 25-hydroxyvitamin D (25-OHD) levels and bone mineral density (BMD) in different age groups and ethnicities and if so, to assess whether there is an identifiable threshold in this association. Analysis was stratified in 6 subgroups by age group (20-49 vs. ³50 years) and ethnicity (White, Mexican American, Black). Weighted linear regression and Lowess smoothed regression plots were used to assess total hip BMD by 25-OHD controlling for sex, BMI, calcium intake, smoking, poverty income ratio, estrogen use, age and month of blood sampling. Compared to the lowest quintile of 25-OHD the highest quintile showed an average increase in BMD by 4.0 g/cm2x10-2 (test for trend; p < .001) in Whites, by 1.8 g/cm2x10-2 (p=.004) in younger Mexican Americans, by 3.2 g/cm2x10-2 in older Mexican Americans (p=.01), and by 2.4 g/cm2x10-2 (p=0.034) in older Blacks. Younger Blacks showed a smaller increase of 1.3 g/cm2x10-2 in BMD (p=.083). In the regression plots BMD increased continuously with higher 25-OHD levels throughout the reference-range of 22.5-94 nmol/l in all subgroups. In younger Whites and younger Mexican Americans, BMD continued to rise beyond 94 nmol/l. Our data indicate that it is advantageous to be at the upper end of the 25-OHD reference-range in younger and older White, Mexican American, and Black individuals.