Kunio Miyanishi

Vitamin D insufficiency in Japanese female college students: a preliminary report.

Vitamin D insufficiency, a risk factor for osteoporosis, has been well investigated in elderly women worldwide, but little information has been available for younger women. This study aimed to determine serum 25-hydroxyvitamin D [25(OH)D] levels in Japanese female college students, and to test whether there is an association between 25(OH)D and bone strength. Subjects were 77 Japanese female junior college students aged 19-24 years. Serum 25(OH)D was measured with high performance liquid chromatography. Bone strength of the calcaneus was evaluated using the osteo sono-assessment index (OSI), a combined index reflecting the bone mass, bone architecture, and elasticity, as measured by quantitative ultrasound densitometry (AOS-100, Aloka). The mean 25(OH)D concentration was 34.2 nmol/L (SD +/- 12.1). The proportion of subjects with 25(OH)D less than 30 nmol/L, a cut-off value for vitamin D insufficiency, was 31/77 (40.3%). Simple linear regression analysis showed that there was a significant linear relationship between 25(OH)D and OSI (R2 = 0.098, p = 0.0069). The association held even after adjusting for weight (partial R2 = 0.098, p = 0.0023). Body weight was also a significant predictor of OSI (partial R2 = 0.105, p = 0.0034). These results suggest that vitamin D insufficiency may be prevalent in healthy young women. Moreover, low levels of 25(OH)D in young women may adversely affect bone strength. An additional, newly designed epidemiological study with a sufficient sample size is needed to confirm the present findings.

Influence of life-related factors and participation in health examination on mortality in a 4.5-year follow-up of a rural cohort

To identify life-related factors causing increased mortality, 2,769 rural residents aged 29-77 were investigated through a self-administered questionnaire in 1990. Death certificates and migration information were inspected during the 4.5-year follow-up period. Age, obesity, life attitude, job, marital status, drinking and smoking habits, previous or current illness, and frequency of participation in health examinations were checked during the baseline survey. The person-year mortality rate was higher among irregular participants in health examinations than among regular participants both among males and females. From Cox’s multiple regression analysis, factors with a significantly high hazard ratio (HR) for mortality were irregular participation (HR=2.05), increase of age (HR=1.54, for 10 years), previous or current illness (HR=2.44), unemployment (HR=1.95), and living without a spouse (HR=2.61) for males; and for females they were having previous or current illness (HR=15.21) and living without a spouse (HR=2.94). Thus, irregular participation in health examinations, unemployment and aging showed a relationship with a higher mortality only in males. A previous or current illness and living without a spouse were related in both sexes.