Association between diet quality evaluated using the Meiji nutritional profiling system and serum 25-hydroxyvitamin D levels in Japanese adults and older adults: A cross-sectional study from the NILS-LSA

The serum 25-hydroxyvitamin D (25OHVD) insufficiency is a recognized public health nutrition concern globally. The relationship between dietary factors and serum 25OHVD levels remains unclear in the Japanese population. This study aimed to evaluate diet quality using the Meiji Nutritional Profiling System (Meiji NPS) and investigated its cross-sectional association with serum 25OHVD levels in Japanese middle-aged and older adults. Data were analyzed from 1,272 middle-aged adults and 873 older adults participating in the National Institute for Longevity Sciences - Longitudinal Study of Aging in Japan. Participants with complete dietary records and serum 25OHVD measurements were included. Diet quality was assessed using the Meiji NPS, and a dietary index was calculated for each individual. Associations between diet quality and serum 25OHVD levels were examined using general linear model adjusted for various covariates. The median age, dietary index, and prevalence of serum 25OHVD insufficiency (< 30 ng/ml) were 53 years, 10.1 points, and 74.2% in adults, and 73.0 years, 12.0 points, and 60.5% in older adults, respectively. Higher dietary indices were positively associated with serum 25OHVD levels in both adults (partial regression coefficient 0.11; 95% confidence interval: 0.04–0.18), and older adults (0.17, 0.07–0.26). This study suggests a positive association between diet quality, as evaluated by the Meiji NPS, and serum 25OHVD levels in middle-aged and older adults. • In the central region of Japan, 74.2% of middle-aged adults and 60.5% of the older adults have insufficient serum 25OHVD levels (<30 ng/mL). • A positive association was observed between diet quality and serum 25OHVD levels in middle-aged adults and older adults. • Accumulation of evidence between dietary factors and serum 25OHVD levels in Japan is needed.