Serum 25-hydroxyvitamin D and cognitive function in Korean older adults living in rural area / 한국영양학회지

ABSTRACT

PURPOSE: This study examined the association between the serum 25-hydroxyvitamin D concentration and the cognitive functions in Korean elderly. METHODS: The subjects were 393 adults aged 60 years or older who participated in the Yangpyeong cohort between July 2009 and August 2010. The subjects were classified into deficiency, insufficiency, or adequacy groups according to the serum 25-hydroxyvitamin D concentration diagnostic criteria suggested by the US Institute of Medicine (IOM). The cognitive function was assessed based on the Korean version of the Mini-Mental State Examination (MMSE-KC). The dietary intake was assessed using the quantitative food frequency questionnaire with 106 food items. RESULTS: The proportions of deficiency, insufficiency, or adequacy in serum 25-hydroxyvitamin D were 6.6%, 44.5%, and 48.9%, respectively. The serum 25-hydroxyvitamin D concentration was significantly higher in men than in women and in outdoor workers than in other occupations. The adequacy group had higher MMSE-KC scores than the other two groups, but not to a significant degree. The proportion of cognitive impairment tended to decrease with increasing serum vitamin D concentration to deficiency, insufficiency, and adequacy (p for trend = 0.029). The deficiency group had a 2.28 times higher risk of cognitive impairment than the adequacy group, but the difference was not statistically significant (OR, 2.28; 95% CI, 0.18 ~ 1.07, p for trend = 0.119). CONCLUSION: The serum vitamin D concentration tended to be associated with the cognitive function in elderly Koreans living in rural areas. To confirm the associations, further longitudinal studies with large samples were required.