Vitamin D concentrations among older adults according to physical disability status: NHANES 2007-2014

Background: older adults are at increased risk of vitamin D deficiency as a result of limited sun exposure and inadequate vitamin D intake. Despite this evidence, there are scarce data regarding the concentration of 25(OH)D and its metabolites among older adults with physical disability. Methods: the National Health and Nutrition Examination Survey 2007-2014 data were collected to compare 25(OH)D3, 25(H)D2, and total 25(OH)D concentrations among adults aged 60 years and older with and without physical disability. Moreover, general linear models adjusted for potential confounders were used to examine the independent effect of vitamin D intake, physical activity status and body mass index (BMI) categories on 25(OH)D concentrations by disability status. Results: of 6,250 older adults, 17.9% were defined as physically disabled. 25(OH)D concentrations were 71.3 and 78.2 nmol/l in subjects with and without disability, respectively. However, after adjustment for potential confounders, similar 25(OH)D concentrations were seen between disabled subjects and their non-disabled counterparts (75.6 vs 77.5 nmol/l; p = 1.17). In contrast, older adults with disability had significantly increased 25(OH)D2 concentrations (8.3 vs 6.1 nmol/l; p < 0.05). Notably, older adults with a daily vitamin D intake of ≥ 15 mcg achieved sufficient 25(OH)D concentrations, regardless of their disability status. Conclusion: 25(OH)D concentrations did not significantly differ among older adults by disability status. This finding was attributed to increased 25(OH)D2 concentrations among those with physical disability. Thus, adequate vitamin D intake is an effective strategy to maintain sufficient 25(OH)D concentrations, particularly among disabled older adults.