Vitamin D is important for maintaining bone health and may prevent various diseases (i.e., cardiovascular disease and cancer). The aim of this study was to estimate vitamin D intakes and to investigate relationship between vitamin D status and osteoporosis of Korean adults using the Korea National Health and Nutrition Examination Survey (KNHANES, 2009) data and a newly established vitamin D database. KNHANES (2009) participants (n = 4,541; 2,021 men; 2,520 women) aged ? 20 years and participants (n = 1,808; 900 men; 908 women) aged ? 50 years who performed bone mineral density (BMD) test were included. Dietary vitamin D intake, serum 25-hydroxyvitaminD (25(OH)D) concentration, food source of vitamin D and the relationship between vitamin D status and serum 25(OH)D were evaluated. In men and women aged ? 20 years, vitamin D intakes adjusted by age and energy intake were 3.93 ± 0.18 ㎍/day and 2.24 ± 0.11 ㎍/day respectively, and serum 25(OH)D concentrations were 21.42 ± 0.77 ng/mL and 18.14 ± 0.68 ng/mL respectively.
The main food sources for vitamin D among participants aged ? 20 are fish and shellfish, eggs, milk and mushrooms like anchovy, mackerel, egg, bastard halibut, pacific saury, hairtail, eel, milk, jew''s-ear and oak mushroom.
The main factors affecting blood concentration overcoming the deficiency (20 ng/mL) were drinking status (P<0.01), sun exposure time (P<0.001), residential area(P<0.05) and the use of vitamin-mineral supplements (P<0.05) in men after adjusting the age and energy intake, only walking (P<0.05), sun exposure time (P<0.01) and the use of supplements in women after adjusting the age, energy intake and menopausal status.
Vitamin D intake of men and women aged <50 was 4.61± 0.32 ㎍/day, 2.96 ± 0.18 ㎍/day respectively, that of men and women aged ≥ 50 was 3.67± 0.49 ㎍/day, 2.56 ± 0.29 ㎍/day respectively. Serum 25(OH)D concentration in men aged < 50 and aged ≥ 50 was 18.10 ± 0.35 ng/mL, 20.95 ± 0.36 ng/mL respectively, and women was 15.71 ± 0.25 ng/mL, 18.04 ± 0.29 ng/mL respectively, and therefore, serum 25(OH)D concentration in men and women aged ≥ 50 was significantly higher than aged < 50 (P<0.001).
In order to investigate if vitamin D intake affects bone mineral density (BMD) in subjects aged ≥ 50, there is a positive relation in BMD of every part of body in total subjects, and only in BMD of lumbar spine in men after adjusting calcuim intake. Also, when calcuim intake is same level, BMD in women is significantly higher when vitamin D intake is high level.
In conclusion, Korean adults, especially women have low vitamin D intake and serum 25(OH)D concentration, and prevalence of osteoporosis is higher in women than in men, so increasing vitamin D intake in women is helpful for increasing serum 25(OH)D concentration and prevention of osteoporosis.