Older adults with vitamin D deficiency are more likely than those with adequate vitamin D levels to have functional limitations, findings from the Longitudinal Aging Study Amsterdam suggest.
These limitations became apparent within 3 years in a cohort aged 65-88 years, compared with 6 years in one aged 55-65 years.
In a cohort of 1,237 adults who were aged 65-88 years at baseline, 56% had at least one functional limitation, and in a second cohort of 725 adults aged 55-65 years at baseline, 30% had at least 1 functional limitation. Those in the older cohort who had vitamin D deficiency, defined as a 25-hydroxyvitamin D (25[OH]D) level of less than 20 ng/mL, had a nearly twofold increased risk of having a functional limitation, compared with those who had a 25(OH)D level greater than 30 ng/mL (odds ratio, 1.7), and those in the younger cohort who had vitamin D deficiency had more than a twofold increased risk (OR, 2.1), according to Dr. Evelien Sohl and her colleagues from the VU University Medical Center, Amsterdam.
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A new study suggests vitamin D deficiency may be linked to various functional limitations in the elderly, including walking stairs, cutting toenails, and walking outside.
Vitamin D status also was associated with the number of functional limitations cross-sectionally, the investigators reported online July 17 in the Journal of Clinical Endocrinology and Metabolism.
"In the fully adjusted models, participants in the older cohort with serum 25(OH)D levels of less than 20 ng/mL had a 1.6 times higher odds for having 1 more functional limitation than participants in the reference category. In the younger cohort, this odds ratio was 1.9," they said (J. Clin. Endocrinol. Metab. 2013 July 17 [doi: 10.1210/jc.2013-1698]).
The investigators also found that vitamin D deficiency was associated with an increase of two or more additional limitations at 3 years in the older cohort (OR, 2.0), but not at 6 years, while the association between vitamin D deficiency and an increase of two or more limitations did not reach significance until after 6 years in the younger cohort (OR, 3.3).
"Age and sex did not significantly modify the associations between serum 25(OH)D and functional status. Relevant confounders were age, sex, body mass index, number of chronic diseases, level of education, and level of urbanization," they said.
Specific functional limitations associated with vitamin D status in the older cohort included walking stairs (OR, 1.8), cutting toenails (OR, 1.5), and walking outside (OR, 2.1). Statistical power was insufficient for analyzing functional limitations in the younger cohort separately because of the low number of limitations in that group.
The Longitudinal Aging Study Amsterdam is an ongoing prospective cohort study of the older Dutch population. Functional limitations were assessed by an interviewer-administered questionnaire. Participants were asked about their ability and degree of difficulty with respect to walking up and down a staircase of 15 steps without resting; dressing and undressing oneself; sitting down and standing up from a chair; cutting one’s toenails; walking outside for 5 minutes without resting; and using one’s own or public transportation. Limitations were defined as any difficulty with performing a specific activity.
Although research on the association between vitamin D status and functional limitations is "scarce and not conclusive," according to the investigators, the findings "are in line with the results of most studies on vitamin D status and physical performance."
"Because functional limitations are a predictor of adverse outcomes, further research is necessary to explore underlying mechanisms and the potential benefits of vitamin D supplements on functional status," they concluded.
The study authors reported having no disclosures.