Mitsue Nashimoto

Low serum concentrations of 25-hydroxyvitamin D in young adult Japanese women: a cross sectional study

OBJECTIVES The vitamin D nutrition status of young adult women is unclear, but a recent preliminary report suggested that they may have vitamin D insufficiency. This study assessed the serum concentrations of 25-hydroxyvitamin D (25[OH]D), an index of vitamin D nutrition status, in young adult Japanese women in comparison with those in older women and investigated whether serum 25(OH)D concentrations are associated with other calcium-related hormones and bone mass. METHODS A cross sectional study of 77 healthy women, age 19 to 66 y, working in nursing homes in Japan was conducted in the winter of 1999 and 2000. The investigation included blood tests, forearm bone mass measurements, and a lifestyle questionnaire. RESULTS The mean serum 25(OH)D concentration in women younger than 30 y was 34.0 nmol/L (standard deviation [SD] = 11.0) and significantly lower than that in women 30 y and older (50.0 nmol/L, SD = 14.4). The proportion of subjects younger than 30 y who had serum 25(OH)D concentrations less than 30 nmol/L was 42.1% and was significantly higher (P < 0.001) than the proportion of those 30 y and older (10.3%). There was a weak but significant linear association between serum 25(OH)D concentrations and forearm bone mineral content (R(2) = 0.114, P = 0.0052) but not between serum 25(OH)D concentrations and bone mineral density. The association held after adjusting for body weight (R(2) = 0.139, P = 0.0111). Serum intact parathyroid hormone concentrations were within the normal range and not associated with serum 25(OH)D concentrations. CONCLUSIONS Serum 25(OH)D concentrations in young adult Japanese women (<30 y old) are lower than those of older adult women (30 to 66 y), and lower serum 25(OH)D concentrations are likely associated with lower forearm bone mineral content.

Fish as a major source of vitamin D in the Japanese diet.

OBJECTIVES We investigated the amount and sources of vitamin D in the Japanese diet by analyzing diet records collected over a 4-mo period. METHODS Dietary data for this study were provided by a nursing home in Niigata, Japan. Diet records, written by the nursing homes dietitian, for 122 consecutive days between September and December 1999, were used. The amount of food for an individual was weighed before cooking and recorded on the diet record. Vitamin D-containing foods, including fish, eggs, meat, and mushrooms, were selected from the diet records, and their vitamin D (vitamin D2 plus D3) per day was calculated by referring to the Standard Tables of Food Composition in Japan. RESULTS The overall average vitamin D intake per day was 7.10 microg (284 IU), which is about 70% of the recommended dietary allowance of 10 microg (400 IU). There were no significant differences in vitamin D values over the 4 mo (P = 0.822). Overall, the contribution of vitamin D from fish to total vitamin D intake was 90.7%, followed by mushrooms (4.4%), eggs (3.2%), and meat (1.7%). CONCLUSIONS Frequent fish intake appears to be an advisable health practice in terms of preventing vitamin D insufficiency in the elderly.

Hypovitaminosis D and hyperparathyroidism in physically inactive elderly Japanese living in nursing homes: relationship with age, sunlight exposure and activities of daily living.

Background and aims: The purposes of this study were to investigate the prevalences of hypovitaminosis D and hyperparathyroidism in physically inactive elderly people living in Japanese nursing homes and determine any correlations with demographic, environmental and/or lifestyle factors. Methods: We targeted 220 elderly people living in nursing homes for the physically disabled in Japan. Of these, 133 (women, 113; men, 20) subjects who agreed and met our inclusion criteria were studied. The average age of the subjects was 84.6 years (SD 8.2). Serum 25-hydroxyvitamin D3 (25[OH]D3), intact parathyroid hormone (intact PTH), creatinine, and albumin concentrations were measured in each subject. Total hours of sunshine during the previous 5 weeks, activities of daily living (ADL) levels, and dietary vitamin D intake were also measured. ADL levels were evaluated using the Physical Self-Maintenance Scale (5-point scale). The examinations were performed between October and December, 1999. Results: The average concentrations of serum 25(OH)D3 and intact PTH were 29.9 nmol/L (SD 13.1) and 5.04 pmol/L (SD 2.27), respectively. The prevalences of hypovitaminosis D (25[OH]D3<30 nmol/L) and hyperparathyroidism (intact PTH>6.90 pmol/L) were 77/133 (57.9%) and 21/133 (15.8%), respectively. Serum 25(OH)D3 concentrations were positively associated with hours of sunshine (R2=0.371, p<0.001) and serum albumin concentrations (R2=0.086, p<0.001), but not with age (p=0.075) or total ADL score (p=0.527). A negative association between serum intact PTH and 25(OH)D3 levels was found in subjects who were 80 years or older (p<0.001) but not in subjects under the age of 80 years. Conclusions: Hypovitaminosis D and hyperparathyroidism are commonly seen in elderly Japanese with low ADL levels. Hypovitaminosis D seems to adversely affect PTH levels, especially in the very elderly.

Weight gain in childhood and bone mass in female college students

The attainment of maximal peak bone mass early on in life is one of the most important strategies for the prevention of osteoporosis in women. The aim of this study was to clarify the correlation between gains in body size in all growth phases in childhood and adult bone mass in women. The subjects were 86 female first-year university students, aged 18–21 years. We measured the subjects’ bone mineral content (BMC) and bone mineral density (BMD) at the lumbar spine and the left hip, including the femoral neck, with dual energy X-ray absorptiometry. Each subject was measured for current height and weight. Height and weight at birth, and at 1.5, and 3 years were obtained from each maternity record book, and those between 6 and 18 years were obtained from their school health records. Other information, including physical activity and calcium intake, was obtained through an interview. Bivariate analysis showed that weight gains during the periods from birth to 1.5 years and from 9 to 12 years significantly correlated with both BMC and BMD values at any site. The stepwise method of multiple regression analysis showed that a weight gain during the period from birth to 1.5 years was significantly associated with BMC at the lumbar spine (P = 0.0001) and at the femoral neck (P = 0.0290) and with BMD at the lumbar spine (P = 0.0387). Birth weight was significantly associated with BMC at the lumbar spine (P = 0.0474) and the total hip (P = 0.0352), and weight gain during the period from 9 to 12 years was significantly associated with BMC at the femoral neck (P = 0.0376). In conclusion, birth weight and weight gain in infancy are important determinants of bone mass in young women. Additionally, a girl’s prepubertal growth spurt is likely to be a key phase for the acquisition of bone mass in relation to body weight. Our findings suggest that osteoporosis prevention programs may need to start very early in the life cycle.

Age and Sex Differences in the Bone Mineral Density of the Distal Forearm Based on Health Check-up Data of 6343 Japanese

Abstract: Bone mineral density (BMD) predicts osteoporotic fractures. The incidence of osteoporotic fractures in Japan is lower than among Caucasians, but fewer data on the BMD of Asians have been reported. This study attempted to clarify the age and sex differences in the forearm BMD of healthy adult Japanese and to assess racial differences between Japanese and Caucasians. The subjects were 6343 healthy adult Japanese (5281 females, 1062 males) who underwent a health check-up at a health care service center between February 1995 and August 1999. Subjects’ age ranged from 15 to 80 years. The BMD of the distal radius and ulna of the non dominant forearm was measured by dual-energy X-ray absorptiometry. Overall, the forearm BMD of men was greater than that of women in all age groups. Peak BMD was 0.484 g/cm2 in the 40–44 year age group of women and 0.590 g/cm2 in the 30–34 year age group of men. The forearm BMD of women under 50 years of age (the average age at menopause) increased slightly with age (2.0%/decade, p<0.0001), but it did not among their male counterparts. After 50 years of age, BMD of the women decreased linearly (–1.6%/year, p<0.0001) with age, the rate of decrease being 1.7-fold faster than in their male counterparts. Rates of gain and loss of forearm BMD differ between the sexes. In comparison with data previously reported, we did not find any evidence of racial differences in BMD as an explanation for the lower incidence of osteoporotic fractures in Japan.

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.

Effect of low-dose calcium supplements on bone loss in perimenopausal and postmenopausal Asian women: A randomized controlled trial

Current standard‐dose calcium supplements (eg, 1000 mg/d) may increase the risk for cardiovascular events. Effectiveness of lower‐dose supplements in preventing bone loss should thus be considered. This study aimed to assess whether calcium supplements of 500 or 250 mg/d effectively prevent bone loss in perimenopausal and postmenopausal Japanese women. We recruited 450 Japanese women between 50 and 75 years of age. They were randomly assigned to receive 500 mg of calcium (as calcium carbonate), 250 mg of calcium, or placebo daily. Medical examinations conducted three times over a 2‐year follow‐up period assessed bone mineral density (BMD) of the lumbar spine and femoral neck. One‐factor repeated measures ANOVA was used for statistical tests. Subgroup analyses were also conducted. Average total daily calcium intake at baseline for the 418 subjects who underwent follow‐up examinations was 493 mg/d. Intention‐to‐treat analysis showed less dramatic decreases in spinal BMD for the 500‐mg/d calcium supplement group compared to the placebo group (1.2% difference over 2 years, p = 0.027). Per‐protocol analysis (≥80% compliance) revealed that spinal BMD for the 500‐mg/d and 250‐mg/d calcium supplement groups decreased less than the placebo group (1.6%, p = 0.010 and 1.0%, p = 0.078, respectively), and that femoral neck BMD for the 500‐mg/d calcium supplement group decreased less relative to the placebo group (1.0%, p = 0.077). A low‐dose calcium supplement of 500 mg/d can effectively slow lumbar spine bone loss in perimenopausal and postmenopausal women with habitually low calcium intake, but its effect on the femoral neck is less certain. Calcium supplementation dosage should thus be reassessed. (Clinical Trials Registry number: UMIN000001176).

Threshold value of serum 25-hydroxyvitamin D concentration in relation to elevated serum parathyroid hormone concentrations in elderly Japanese women.

This study was designed to determine the threshold value for 25-hydroxyvitamin D [25(OH)D] concentration in relation to elevated serum parathyroid hormone (PTH) concentrations in elderly Japanese women. The subjects were 582 noninstitutionalized, ambulant women who lived in a community in Japan. Serum 25(OH)D concentrations were determined using the Nichols Advantage chemiluminescent assay, and serum intact PTH concentrations were determined with a two-site immunoradiometric assay. Demographic characteristics, calcium intake, and serum 1,25(OH)2D levels were also determined. The average age, body mass index (BMI), and calcium intake of the subjects were 74.5 years (SD 4.5), 23.3 kg/m2 (SD 3.4), and 579 mg/day (SD 248), respectively. The serum log-transformed intact PTH concentration was significantly predicted by the serum 25(OH)D concentration (r = −0.147, P = 0.0004), but not by age, BMI, the serum log-transformed 1,25(OH)2D concentration, or the log-transformed calcium intake. Analysis of variance with Dunnetts multiple comparisons showed that mean serum intact PTH concentrations with serum 25(OH)D concentrations less than 30 nmol/l (mean intact PTH = 5.89 pmol/l, P < 0.0001) and in the range 30–39 nmol/l (mean intact PTH = 4.54 pmol/l, P = 0.0067) were significantly higher than mean intact PTH concentrations for serum 25(OH)D concentrations greater than 50 nmol/l (mean intact PTH = 3.65 pmol/l, the baseline level), but the mean serum intact PTH concentration for 25(OH)D concentrations in the range 40–49 nmol/l (mean intact PTH = 3.70 pmol/l, P = 0.9975) was not. We conclude that serum 25(OH)D for ambulant elderly Japanese women should be maintained at 40 nmol/l or higher.

Low calcium intake is associated with increased bone resorption in postmenopausal Japanese women: Yokogoshi Study.

OBJECTIVE Low Ca intake is common among Japanese women, but its effect on bone metabolism has not been fully elucidated. The aim of the present study was to determine the relationship between Ca intake and serum markers of bone turnover in postmenopausal Japanese women. DESIGN A cross-sectional study. SETTING A community setting. SUBJECTS Subjects were 595 home-dwelling postmenopausal Japanese women. Ca intake was assessed by a validated FFQ. Serum type I collagen cross-linked N-telopeptides (NTX) and osteocalcin were measured as markers of bone turnover. The relationships between demographic characteristics, lifestyles, serum Ca, vitamin D and intact serum parathyroid hormone and bone turnover were also assessed. RESULTS The average age of the subjects was 64.5 (sd 5.8) years and the mean Ca intake was 527 (sd 160) mg/d. Ca intake was significantly associated with serum NTX (P = 0.0104), but not with serum osteocalcin. Mean serum NTX concentration in the lowest quartile of Ca intake (<417 mg/d) was significantly higher than in the fourth, referent quartile. Among these Japanese postmenopausal women, very low Ca intake (less than approximately 400 mg/d) was associated with increased bone resorption but not bone formation. CONCLUSIONS Increased bone resorption may be one mechanism by which this Ca-depleted population normalizes bone metabolism and prevents osteoporosis.

Are the Serum 25-Hydroxyvitamin D Concentrations in Winter Associated with Forearm Bone Mineral Density in Healthy Elderly Japanese Women?

The objective of this study was to investigate whether the serum 25-hydroxyvitamin D (25[OH]D) concentrations in winter are associated with the BMD in elderly Japanese women. The subjects were 117 healthy elderly Japanese women. Serum 25(OH)D concentrations were determined by high-performance liquid chromatography. Forearm BMD in the non-dominant arm was measured by dual-energy X-ray absorptiometry (DXA) using a DTX-200 Osteometer. The mean age of the subjects was 66.1 (SD 6.5) years (range: 46-80). The average 25(OH)D concentration was 59.1 nmol/L (SD 16.1), and five of the subjects had low 25(OH)D concentrations (< 30 nmol/L). Forearm BMD decreased linearly with age (r2 = 0.275). There was no linear association between the serum 25(OH)D concentrations and the forearm BMD (p = 0.9483). Multiple regression analysis did not reveal any association between the two (p = 0.5318) when age (p < 0.0001, r2 = 0.271) and weight (p < 0.0001, r2 = 0.153) were taken into account. Our cross-sectional study failed to reveal any association between the serum 25(OH)D concentrations and the forearm BMD in elderly Japanese women, suggesting that 25(OH)D does not play an important role in the determination of BMD. A follow-up study should be conducted to confirm the results of our cross-sectional study.