Determinants of vitamin D supplementation among older adults and its effect on 25(OH)D levels according to bone mineral density status

Abstract

Background: although supplementation with vitamin D has been reported as a main determinant of 25-hydroxyvitamin D status [25(OH)D] levels, there are limited data in regard to the factors associated with vitamin D supplementation in older adults. Aims: to examine the characteristics of participants associated with vitamin D supplement use and its effect on 25(OH)D concentrations according to bone mineral density (BMD). Methods: the present analysis was based on data from participants aged 60 years and older in the National Health and Nutrition Examination Survey. Logistic regression models were created to examine the demographic, lifestyle, and health characteristics associated with vitamin D supplementation. Moreover, general linear models were assembled to assess the effect of vitamin D supplement doses on 25(OH)D concentrations according to BMD status. Results: of 5,204 participants, 45.3 % reported taking vitamin D supplements, at least 400 IU per day. Overall, women, non-Hispanic whites, college education, former smokers, physical activity, and > 2 comorbidities were variables significantly associated with increased odds of taking vitamin D supplements. Notably, among subjects with osteoporosis, those taking vitamin D supplements between 400 and 800 IU per day had on average 20.7 nmol/L higher 25(OH)D concentrations compared with their non-user counterparts. Conclusions: demographic and healthy lifestyle characteristics are the main determinants of vitamin D supplement use among older adults. Moreover, even among subjects with low bone mass, vitamin D supplements between 400 and 800 IU per day are adequate to reach sufficient 25(OH)D concentrations.