How much vitamin D3 do the elderly need?

BACKGROUND: Vitamin D insufficiency poses a problem in many parts of the world, the elderly being an especially vulnerable group. This insufficiency results from an inadequate amount of sunshine and a low dietary intake of vitamin D. Typically, insufficiency is accompanied with high intact parathyroid hormone, (S-iPTH) concentrations. AIMS OF THE STUDY: We studied how serum 25-hydroxy vitamin D (S-25-OHD) concentrations respond to different doses of vitamin D3 supplementation. Secondly to determine the smallest efficient dose to maintain serum 25-OHD concentration above the insufficiency level. We also studied which dose would be efficient in decreasing S-iPTH concentration in these subjects. SUBJECTS AND METHODS: Forty-nine 65- to 85-year-old women participated. The women were randomly assigned into one of four groups receiving 0 (placebo), 5, 10 or 20 microg of vitamin D3 daily for 12 weeks. Fasting morning blood was drawn at the beginning of the study, and thereafter every second week. Calciotropic variables were assessed from serum and urine samples. RESULTS: The S-25-OHD concentration increased significantly (p < 0.001) in all supplemented groups [5 microg: by 10.9 (8.5) nmol/L, 10 microg: by 14.4 (6.9) nmol/L, 20 microg: by 23.7 (11.9) nmol/L], whereas it decreased in the placebo group by 8.3 (13.2) nmol/L. Equilibrium in S-25-OHD concentration was reached in all groups after 6 weeks of supplementation at 57.7 (8.9) nmol/L, 59.9 (8.9) nmol/L and 70.9 (8.9) nmol/L in the groups with increasing vitamin D supplementation. The dose-response to supplementation decreased with increasing vitamin D status at baseline, r = -0.513, p = 0.002. S-iPTH tended to decrease in those with highest dose response to supplementation. CONCLUSIONS: A clear dose response was noted in S-25-OHD to different doses of vitamin D3. The recommended dietary intake of 15 microg is adequate to maintain the S-25-OHD concentration around 40-55 nmol/L during winter, but if the optimal S-25-OHD is higher than that even higher vitamin D intakes are needed. Interestingly, subjects with lower vitamin D status at baseline responded more efficiently to supplementation than those with more adequate status.     

Vitamin D deficiency: a concern in premenopausal Bangladeshi women of two socio-economic groups in rural and urban region

OBJECTIVE: The study was designed to evaluate the vitamin D status in women of different physiological status of two socio-economic groups in Bangladesh. DESIGN: A cross-sectional study, using serum 25-hydroxyvitamin D (25-OHD), calcium, phosphorus and alkaline phosphatase activity. SETTING: Two regions of Bangladesh. The Dhaka city area and west region of Nandail (Betagair Union), Mymensingh. SUBJECTS: Representative subjects of two groups (low socio-economic group=group L, n=99; and high socio-economic group=group H, n=90) of Bangladeshi women aged 16-40 y. About 87% of the subjects were housewives and the rest, 13%, were distributed among other different professions. Each group comprised of three sub-groups (non-pregnant non-lactating=1, pregnant=2, and lactating=3). RESULTS: The influence of socio-economic status and physiological status on serum 25-OHD concentration (P=0.038, P=0.015, respectively), serum calcium concentration (P<0.001, P<0.001, respectively) and alkaline phosphatase activity (P<0.001, P<0.001, respectively) were observed. The distribution of serum 25-OHD concentration in both groups was shifted overall toward the lower limit of the normal range. Seventeen percent of women in group L and 12% of women in group H had serum 25-OHD concentration <25 nmol/l. Hypovitaminosis D (serum 25-OHD concentration < or = 37.5 nmol/l) was observed in 50% of subjects in group L and 38% of subjects in group H, respectively. The prevalence of hypovitaminosis was higher in lactating subjects of the groups L and H (63 and 46%, respectively) than in the other sub-groups in the same group. CONCLUSIONS: The results of the study suggested that women in Bangladesh were at risk of hypovitaminosis D and lactation was an additional risk factor in low income groups. The situation may increase the risk of bone loss.     

25-Hydroxyvitamin D and 1,25-dihydroxyvitamin D of D2 and D3 origin in maternal and umbilical cord serum after vitamin D2 supplementation in human pregnancy

Serum concentrations of 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D [1,25-(OH)2D] of vitamin D2 and D3 origin were determined separately in 10 women before vitamin intake in early pregnancy, and repeated in maternal and cord serum obtained at delivery after 20 to 30 wk of vitamin D2 supplementation in a dose of 400 IU/day. Before supplementation 25-OHD2 and 1,25-(OH)D2D2 were present in just traceable or nondetectable concentrations, but the levels increased in all to a mean +/- 1 SD of 7.3 +/- 3.7 ng/ml and 37.2 +/- 18.1 pg/ml, respectively (p less than 0.0025), by the time of delivery. At delivery the total 25-OHD and 1,25-(OH)2D levels were always lower in the cord than in the maternal serum (30.7 +/- 14.2 versus 20.1 +/- 9.1 ng/ml, and 90.1 +/- 31.2 versus 37.3 +/- 11.6 pg/ml, p less than 0.0025). The paired concentrations of 25-OHD were closely related (r = 0.89, p less than 0.0005), while the association for 1,25-(OH)2D was not statistically significant (r = 0.53, p less than .01). The 25-OHD of D2 and D3 origin accounted for a similar proportion of the total 25-OHD in the maternal and cord serum (ratio of 25-OHD2 to 25-OHD3: 0.40 +/- 0.28 versus 0.45 +/- 0.29, p = NS), as did the respective 1,25-(OH)2D metabolites [ratio of 1,25-(OH)2D2 to 1,25-(OH)2D3: 0.73 +/- 0.35 versus 0.90 +/- 0.50, p = NS].(ABSTRACT TRUNCATED AT 250 WORDS)     

The vitamin D status of a cohort of postmenopausal non-institutionalized canadian women

Dietary vitamin D intakes, calculated from three-day dietary records, and serum 25-OHD levels were determined in a cohort of 96 non-instituonalized Canadian wome, of above average social status, aged 67.2±6.6 yr (mean±SD, range 58–89 yr). Dietary vitamin D intake (without supplements) was 4.3±2.2 ug/day; 20% of the subjects had intakes below the Canadian recommended nutrient intake (2.5 ug/day). Serum 25-OHD levels (mean±SD = 16.5±5.3 ng/ml) were not related to vitamin D supplement usage or season. Eight subjects had serum 25-OHD levels < 10 ng/ml. They were all unsupplemented, constituting 11% of this subgroup and they were significantly older (72.3±9.3 yr) (p=0.02) than subjects with serum 25-OHD values > 10 ng/ml (67.0±6.4 yr). There were indications that serum 25-OHD levels were positively coreelated with dietary vitamin D intakes (r=0.19; p=0.07) and negatively correlated with age (r=−0.21; p=0.05). Multiple regression analysis also indicated that serum 25-OHD levels were related to age and dietary vitamin D intakes (F=4.25; p<0.02). The small number of subjects with low serum 25-OHD was consonant with the relatively high consumption of vitamin D fortified dairy products by the study group.     

Adolescent girls in Maine are at risk for vitamin D insufficiency

The objective was to determine the seasonal fluctuations in serum 25-hydroxyvitamin D (25-OHD) in a group of healthy adolescents living in a northern climate. Twenty-three 9- to 11-year-old girls participated in the study from September 2000 to March 2003. Serum 25-OHD and parathyroid hormone levels were measured each September and March. Dietary intake of vitamin D was assessed each summer and winter. Summer-sun exposure was evaluated using reports of time spent outdoors. The mean decrease in serum 25-OHD from September to March was 28%. Vitamin D insufficiency (at least one serum 25-OHD level <50 nmol/L) was observed in 11 of 23 (48%) subjects. Four of 23 subjects (17%) exhibited vitamin D insufficiency in both September and March. Mean parathyroid hormone levels increased 4 pg/mL (15%) from September to March. Vitamin D intakes need to be increased in winter at northern latitudes.     

Vitamin D fortification as public health policy: significant improvement in vitamin D status in young Finnish men

BACKGROUND: Vitamin D insufficiency is common in northern countries during wintertime. In Finland, after the recommendation by the Ministry of Social Affairs and Health, vitamin D has been added to liquid milk products and margarines from February 2003. OBJECTIVE: We determined the effects of national policy on vitamin D fortification on vitamin D status among young Finnish men. DESIGN: A comparison before and after intervention with study population of 196 young Finnish men (18-28 years) was carried out. Serum 25-hydroxyvitamin D3 (25-OHD3) concentrations were determined with the OCTEIA enzymeimmunoassay by IDS (Immunodiagnostic Systems Limited, Bolden, UK) in January 2003 (n = 96) and in January 2004 (n = 100), nearly 1 year after national vitamin D fortification had started. RESULTS: The mean serum 25-OHD3 concentrations during the wintertime increased by 50% after implementation of the vitamin D fortification of dairy products. Correspondingly, the prevalence of vitamin D insufficiency (serum 25-OHD3 < 40 nmol/l) was decreased by 50% from 78% in January 2003 to 35% in January 2004. CONCLUSIONS: Our results demonstrate that national vitamin D fortification substantially improved the vitamin D status of young Finnish men. Still, a third remained vitamin D insufficient.     

Vitamin D and Bone Health of Older Adults within Care Homes: An Observational Study

Limited studies have reported vitamin D status and health outcomes in care home residents, a group at risk of vitamin D deficiency. This study investigated serum 25-hydroxyvitamin D (25-OHD) concentrations in older adults within care homes in Northern Ireland (NI) and its association with musculoskeletal health (ultrasound T-score, muscle strength, Timed Up & Go test (TUG)), bone turnover markers (BTMs), and immune function markers. A total of 87 participants were recruited with mean ± SD age 83.2 ± 7.9 years. Mean ± SD serum 25-OHD concentration (n 69) was 49.52 ± 35.58 nmol/L. Vitamin D deficiency (25-OHD <25 nmol/L) was observed in 34.8% (n 24) of participants with 17.4% (n 12) classified as insufficient (25-OHD 25–50 nmol/L) and 47.8% (n 33) as sufficient (25-OHD >50 nmol/L). 25-OHD concentration was not an independent predictor of T-score, muscle strength, TUG, or inflammatory cytokines. After adjusting for covariates, a significant negative association was observed between 25-OHD concentration and the BTMs; osteocalcin (β = −0.395; p = 0.001), procollagen type 1 N propeptide (P1NP) (β = −0.320; p = 0.012), and C-terminal telopeptide of type 1 collagen (CTX) (β = −0.377; p = 0.003). Higher 25-OHD concentration was positively associated with use of vitamin D ± calcium supplementation (β = 0.610; p < 0.001). Vitamin D deficiency and insufficiency were highly prevalent in this sample of care home residents in NI. Higher 25-OHD concentration was associated with greater supplement use and with reduced bone turnover, which in this population is linked with reduced bone loss. These findings emphasize the need for a mandatory vitamin D ± calcium supplementation policy specific for care home residents.     

Prospective study on food fortification with vitamin D among adolescent females in Finland: minor effects

Vitamin D insufficiency is common particularly during winter time. After the recommendation by the Ministry of Social Affairs and Health, Finnish fluid milks and margarines have been fortified with vitamin D since February 2003. The aims of the present study were to examine the impact of vitamin D fortification of food supplies on serum 25-hydroxyvitamin D (S-25(OH)D) concentrations and on daily dietary vitamin D intake among adolescent females. One hundred and forty-two girls of Caucasian ethnicity aged 12-18 years completed semi-quantitative FFQ from which the dietary vitamin D and Ca intakes were calculated. S-25(OH)D was measured by radioimmunoassay. The study was performed from February-March 2000 to February-March 2004, one year after the initiation of fortification. The mean dietary intake of vitamin D was < 7.5 microg in 91.5 % of the adolescent girls in 2000 and 83.8 % in 2004. The midwinter mean S-25(OH)D concentration did not change significantly during the follow-up period (48.3 v. 48.1 nmol/l, NS). The proportion of participants who had S-25(OH)D concentration < 50 nmol/l was 60.6 % in 2000 and 65.5 % in 2004. Only 7.0 % of the participants had an adequate S-25(OH)D ( >or= 75 nmol/l) level in 2000 or 4 years later. The vitamin D fortification of fluid milks and margarines was inadequate to prevent vitamin D insufficiency. There are numerous adolescent girls and women who are not reached by the current fortification policy. Therefore new innovative and feasible ways of improving vitamin D nutrition are urged.     

The vitamin D status of East Indian Punjabi immigrants to Canada

1. Serum 25-hydroxyvitamin D (25-OHD), calcium and alkaline phosphatase (EC 3.1.3.1) levels and vitamin D intakes (from 3 d weighed dietary records) were determined in a cohort of fifty-nine male East Indian Punjabi immigrants (37.7 (SD 10.5) years) and fifty-four females (33.3 (SD 7.4) years). 2. Females had somewhat lower mean serum 25-OHD levels (12.3 (SD 5.0) v. 14.2 (SD 5.1) ng/ml, P less than 0.05) and serum Ca levels (88 (SD 8) v. 91 (SD 6) mg/l) than males (P less than 0.05) whereas serum alkaline phosphatase values (males 167 (SD 63), females 169 (SD 43) IU/l) and dietary vitamin D intakes (males 3.5 (SD 1.8), females 3.3 (SD 2.0) micrograms/d) were similar. 3. 22% of the females and 12% of the males had serum 25-OHD levels below 9.0 ng/ml but none had serum 25-OHD levels within the range associated with clinically overt disease. 4. In the males, serum 25-OHD levels were negatively correlated with dietary fibre intakes (g/d; r -0.29; P less than 0.05). 5. Multiple-regression analysis indicated that log serum 25-OHD levels were not related to dietary vitamin D intakes. Instead they were associated with sex and dietary fibre intakes (g/MJ) (F 3.71; P = 0.03). These two variables explained 8% of the variance.     

Time spent outdoors and seasonal variation in serum concentrations of 25-hydroxyvitamin D in Korean women

The vitamin D status of 179 Korean women between the ages of 20 and 75 were measured by the use of high performance liquid chromatography (HPLC). Related biochemical indices such as iPTH, alkaline, phosphatase, creatinine, albumin, Ca, Mg, and P were also measured. Factors such as demographic characteristics, intake of foods containing vitamin D, and proxy measure of sunlight exposure (time spent outdoors) were assessed to determine their effect on vitamin D status and used in the analysis. The purpose of this study was twofold. The first was to define reference data for the distribution of vitamin D status and to explore the relationship between vitamin D and the variables that affect the vitamin D status in Korean women. The second was to analyze the risk factors of the vitamin D status and the relation between the factors. The results of this study will provide valuable information regarding the role of vitamin D in Korean women. The mean serum 25-hydroxyvitamin D (25-OHD) level was 25.8 ng/ml. Of the total subjects, 16.5% showed vitamin D deficiency (i.e. s-25-OHD < 10 ng/ml). Serum 25-OHD was inversely related to iPTH and alkaline phophatase. There were significant changes in serum 25-OHD level from the pre- to the post-menopausal women with a positive correlation between vitamin D intake and serum at the 25-OHD level. Significant seasonal variation of serum 25-OHD and PTH were noted in 26 of the subjects and the serum 25-OHD level also correlated with sunlight exposure especially at 12.00 p.m. to 2.00 p.m. as assessed by the time spent outdoors. The relative importance of the two sources of vitamin D such as dietary intake (33.6% explained) and endogenous production of the time spent outdoors (19.7% explained) in serum 25-OHD were also evaluated. Multiple regression analysis revealed that the effects of aging on serum 25-OHD could largely be accounted for. Both the decline in dietary vitamin D intake and the time spent outdoors were closely related to the decreasing serum 25-OHD level. Among the determinants of low serum 25-OHD were age, dietary vitamin D intake, serum calcium level and dietary calcium intake, and serum alkaline phosphatase.     

Time spent outdoors and seasonal variation in serum concentrations of 25-hydroxyvitamin D in Korean women

The vitamin D status of 179 Korean women between the ages of 20 and 75 were measured by the use of high performance liquid chromatography (HPLC). Related biochemical indices such as iPTH, alkaline, phosphatase, creatinine, albumin, Ca, Mg, and P were also measured. Factors such as demographic characteristics, intake of foods containing vitamin D, and proxy measure of sunlight exposure (time spent outdoors) were assessed to determine their effect on vitamin D status and used in the analysis. The purpose of this study was twofold. The first was to define reference data for the distribution of vitamin D status and to explore the relationship between vitamin D and the variables that affect the vitamin D status in Korean women. The second was to analyze the risk factors of the vitamin D status and the relation between the factors. The results of this study will provide valuable information regarding the role of vitamin D in Korean women. The mean serum 25-hydroxyvitamin D (25-OHD) level was 25.8 ng/ml. Of the total subjects, 16.5% showed vitamin D deficiency (i.e. s-25-OHD < 10 ng/ml). Serum 25-OHD was inversely related to iPTH and alkaline phosphatase. There were significant changes in serum 25-OHD level from the pre- to the post-menopausal women with a positive correlation between vitamin D intake and serum at the 25-OHD level. Significant seasonal variation of serum 25-OHD and PTH were noted in 26 of the subjects and the serum 25-OHD level also correlated with sunlight exposure especially at 12.00 p.m. to 2.00 p.m. as assessed by the time spent outdoors. The relative importance of the two sources of vitamin D such as dietary intake (33.6% explained) and endogenous production of the time spent outdoors (19.7% explained) in serum 25-OHD were also evaluated. Multiple regression analysis revealed that the effects of aging on serum 25-OHD could largely be accounted for. Both the decline in dietary vitamin D intake and the time spent outdoors were closely related to the decreasing serum 25-OHD level. Among the determinants of low serum 25-OHD were age, dietary vitamin D intake, serum calcium level and dietary calcium intake, and serum alkaline phosphatase.     

Vitamin D insufficiency in children, adolescents, and young adults with cystic fibrosis despite routine oral supplementation

BACKGROUND: Cystic fibrosis (CF) with pancreatic insufficiency is associated with poor absorption of fat and fat-soluble vitamins, including vitamin D. Pancreatic enzyme supplementation does not completely correct fat malabsorption in CF patients. OBJECTIVE: The objective of the study was to compare the vitamin D status of children, adolescents, and young adults with CF who were treated with routine vitamin D and pancreatic enzyme supplements with the vitamin D status of a healthy reference group from a similar geographic area. DESIGN: Growth, dietary intake, and serum concentrations of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)(2)D], and parathyroid hormone (PTH) were measured in 101 white subjects with CF and a reference group of 177 white subjects. RESULTS: The median daily vitamin D supplementation in the CF group was 800 IU. The mean +/- SD serum concentrations of 25(OH)D were 20.7 +/- 6.5 ng/mL in the CF group and 26.2 +/- 8.6 ng/mL in the reference group (P < 0.001). Vitamin D deficiency and insufficiency were defined as 25(OH)D concentrations < 11 ng/mL and < 30 ng/mL, respectively. Seven percent of the CF group and 2% of the healthy reference group were vitamin D deficient (P < 0.03). Ninety percent of the CF group and 74% of the healthy reference group were vitamin D insufficient (P < 0.01). Twenty-five percent of the CF group and 9% of the healthy reference group had elevated PTH (P < 0.006). The odds of vitamin D insufficiency in the CF group, compared with the healthy reference group, were 1.2 (95% CI: 1.1, 1.3) after adjustment for season and age. CONCLUSION: Despite daily vitamin D supplementation, serum 25(OH)D concentrations remain low in children, adolescents, and young adults with CF.     

Efficacy and safety of vitamin D3 intake exceeding the lowest observed adverse effect level

BACKGROUND: The Food and Nutrition Board of the National Academy of Sciences states that 95 microg vitamin D/d is the lowest observed adverse effect level (LOAEL). OBJECTIVE: Our objective was to assess the efficacy and safety of prolonged vitamin D3 intakes of 25 and 100 microg (1000 and 4000 IU)/d. Efficacy was based on the lowest serum 25-hydroxyvitamin D [25(OH)D] concentration achieved by subjects taking vitamin D3; potential toxicity was monitored by measuring serum calcium concentrations and by calculating urinary calcium-creatinine ratios. DESIGN: Healthy men and women (n = 61) aged 41 +/- 9 y (mean +/- SD) were randomly assigned to receive either 25 or 100 microg vitamin D3/d for 2-5 mo, starting between January and February. Serum 25(OH)D was measured by radioimmunoassay. RESULTS: Baseline serum 25(OH)D was 40.7 +/- 15.4 nmol/L (mean +/- SD). From 3 mo on, serum 25(OH)D plateaued at 68.7 +/- 16.9 nmol/L in the 25-microg/d group and at 96.4 +/- 14.6 nmol/L in the 100-microg/d group. Summertime serum 25(OH)D concentrations in 25 comparable subjects not taking vitamin D3 were 46.7 +/- 17.8 nmol/L. The minimum and maximum plateau serum 25(OH)D concentrations in subjects taking 25 and 100 microg vitamin D3/d were 40 and 100 nmol/L and 69 and 125 nmol/L, respectively. Serum calcium and urinary calcium excretion did not change significantly at either dosage during the study. CONCLUSIONS: The 100-microg/d dosage of vitamin D3 effectively increased 25(OH)D to high-normal concentrations in practically all adults and serum 25(OH)D remained within the physiologic range; therefore, we consider 100 microg vitamin D3/d to be a safe intake.     

Prevalence of vitamin D deficiency and secondary hyperparathyroidism during winter in pre-menopausal Bangladeshi and Somali immigrant and ethnic Finnish women: associations with forearm bone mineral density

Secondary hyperparathyroidism (SHPT) is one of the outcomes of vitamin D deficiency that negatively affects bone metabolism. We studied the ethnic differences in vitamin D status in Finland and its effect on serum intact parathyroid hormone (S-iPTH) concentration and bone traits. The study was done in the Helsinki area (60°N) during January-February 2008. A total of 143 healthy women (20-48 years of age) from two groups of immigrant women (Bangladeshi, n 34 and Somali, n 48), and a group of ethnic Finnish women (n 61) were studied in a cross-sectional setting. Serum concentrations of 25-hydroxyvitamin D (S-25OHD) and S-iPTH were measured. Peripheral quantitative computed tomography measurements were taken at 4 and 66?% of the forearm length. In all groups, the distribution of S-25OHD was shifted towards the lower limit of the normal range. A high prevalence of vitamin D insufficiency (S-25OHD?65?ng/l) was higher (79·1?%) in Somali women than in Finnish women (16?%). There was a significant association between S-25OHD and S-iPTH (r?-?0·49, P?相似文献   

Prevalence of vitamin D deficiency among adult population of Isfahan City, Iran

Determination of vitamin D status in different age-groups in a community and in different climates of a country is necessary and has important implications for general health. The study was conducted to determine the prevalence of vitamin D deficiency among the adult population of Isfahan, a centrally-located city in Iran. In this cross-sectional study, 1,111 healthy people-243 men and 868 women--aged 41.4 (mean 14 and range 20-80) years, who attended a single-consultation outpatient clinic, were selected. Serum 25-hydroxy vitamin D (25-OHD), parathyroid hormone (PTH), calcium and phosphorus concentrations were measured. Mild, moderate and severe vitamin D deficiencies were defined as 25-OHD values of 20-30 ng/mL, 10-20 ng/mL, and < 10 ng/mL respectively. The median (range) concentrations of 25-OHD were 21 (4.0-105.0) ng/mL in males and 18 (1.5-117) ng/mL in females (p = 0.05). The prevalence of mild, moderate and severe vitamin D deficiencies among the adult population was 19.6%, 23.9%, and 26.9% respectively. Vitamin D deficiency was more prevalent among women (p = 0.001) and younger age-group (p = 0.001). Medians of 25-OHD in spring-summer and autumn-winter were 21 ng/mL and 18 ng/mL respectively (p = 0.005). The prevalence of severe vitamin D deficiency was higher in autumn-winter than in spring-summer (odds ratio = 1.6, 95% confidence interval 1.2-2.2, p = 0.001). The prevalence of vitamin D deficiency was high in a sunny city--Isfahan--especially among women and younger population. The high prevalence of vitamin D deficiency in this city emphasizes the necessity of vitamin D supplementation as more exposure to sun is limited due to the type of clothing required by current law.     

Vitamin D status in kidney transplant patients: need for intensified routine supplementation

BACKGROUND: A high prevalence of vitamin D insufficiency has been found in the general population and in patients with chronic kidney disease. OBJECTIVE: The aim was to examine vitamin D status and determinants and metabolic correlates of serum 25-hydroxyvitamin D in a population of adult Danish kidney transplant patients. DESIGN: This was a cross-sectional study of 173 adult kidney transplant patients with a mean (+/-SD) age of 53.4 +/- 11.7 y and a median graft age of 7.4 y (interquartile range: 3.3-12.7 y). Serum concentrations of intact parathyroid hormone (S-PTH), 25-hydroxyvitamin D [S-25(OH)D], and 1,25-dihydroxyvitamin D [S-1,25(OH)(2)D] were measured. Dietary and supplementary intake of vitamin D, avoidance of solar ultraviolet B exposure, and selected lifestyle factors were assessed in a subgroup (n = 97). RESULTS: Fifty-one percent of the patients had vitamin D insufficiency [S-25(OH)D 40-75 nmol/L], and an additional 29% had moderate-to-severe vitamin D deficiency [S-25(OH)D < or = 39 nmol/L]. In multiple regression analysis, sun avoidance (negative association) and vitamin D supplementation (positive association) were independent determinants of S-25(OH)D concentrations. Low S-25(OH)D concentrations were associated with 1) increased S-PTH concentrations (P = 0.0002), independently of S-1,25(OH)(2)D concentrations, and 2) decreased S-1,25(OH)(2)D concentrations (P = 0.002), independently of graft function. CONCLUSIONS: Hypovitaminosis D is common among Danish kidney transplant patients and is associated with reduced concentrations of S-1,25(OH)(2)D and increased S-PTH concentrations. Sun avoidance and vitamin D supplementation are important determinants of vitamin D status. The observed hypovitaminosis D might be corrected by intensified routine vitamin D supplementation as opposed to the current supplementation practice.     

Vitamin D fortification of milk products does not resolve hypovitaminosis D in young Finnish men

OBJECTIVE:To study if vitamin D fortification of milk products started in February 2003 has improved vitamin D status of young Finnish men, which has been poor before. DESIGN: A longitudinal study of one cohort. SETTING: Helsinki University Central Hospital. SUBJECTS: Sixty-five healthy men, studied for the first time in January 2001, were re-examined in January 2004. They were aged 18-21 years in 2001. METHODS: Blood was sampled for determination of serum 25-hydroxyvitamin D (25-OHD) and intact parathyroid hormone (iPTH). 25-OHD was measured by both radioimmunoassay (RIA) and high-pressure liquid chromatography (HPLC). Consumption of milk, sour milk and fish and use of vitamin D supplements were assessed using a questionnaire. RESULTS: In January 2004, vitamin D fortification had raised serum 25-OHD level, with the mean of individual percent changes being 20.4% measured with RIA (P=0.0015). The correlation between the RIA and HPLC methods was high (r=0.85). Nineteen men (29.2%) had vitamin D deficiency (25-OHD相似文献   

Vitamin D status is associated with bone mineral density in adolescents: Findings from the Korea National Health and Nutrition Examination Survey

Vitamin D is a factor that regulates calcium and bone metabolism. However, the clinical effect of vitamin D on bone mineral density (BMD) remains controversial. We hypothesized that sufficient vitamin D is required to maintain optimal BMD in adolescents. Based on the Korea National Health and Nutritional Examination Survey, data of 1063 adolescents aged 12 to 18 years were analyzed. The association of vitamin D status and other variables, such as body mass index (BMI), calcium intake, physical activity, lean mass, and fat mass, with BMD Z-scores in the lumbar spine, whole body, total femur, and femur neck were examined. We defined vitamin D deficiency as < 12 ng/mL, vitamin D insufficiency as 12 to 20 ng/mL, and sufficiency as > 20 ng/mL according to the 25-hydroxyvitamin D (25-OHD) level. The mean 25-OHD concentration of subjects was below normal, at 16.28 ng/mL. Subjects with vitamin D deficiency, insufficiency, and sufficiency comprised 20.5%, 58.6%, and 20.9% of all subjects, respectively. The vitamin D sufficient group had higher BMD Z-scores compared to the insufficient group, and the insufficient group had higher BMD Z-scores compared to the deficient group. In linear regression analysis, 25-OHD level, BMI, calcium intake, physical activity, lean mass, and fat mass were positively associated with BMD Z-scores. 25-OHD level was positively associated with BMD Z-scores, even after adjusting for other factors. This study suggests that vitamin D status is positively associated with BMD in adolescents; therefore, maintaining sufficient vitamin D levels during adolescence is crucial to prevent low BMD.     

Vitamin D Knowledge,Awareness, and Attitudes of Adolescents and Adults: A Systematic Review

IntroductionThe aims of this systematic review were 2-fold: (1) evaluate the effect of vitamin D educational interventions on serum 25-hydroxyvitamin D (25-OHD) concentration in adolescents (aged 10–19 years) and adults, and (2) assess the association between serum 25-OHD concentration and vitamin D knowledge, awareness of vitamin D deficiency risk, and attitudes toward behaviors associated with acquiring vitamin D.MethodsMedline, CINAHL, Embase, and SPORTDiscus were systematically searched for studies reporting associations between serum 25-OHD concentration and vitamin D knowledge, awareness, and attitudes. Results were summarized narratively. Effect sizes were calculated when data were available.ResultsEight studies reported experimental effects (2 randomized controlled trials, 1 cluster randomized trial, 4 quasi-experiments, 1 clinical audit), and 14 reported cross-sectional associations. Seven of 8 interventions reported no effect of educational interventions on serum 25-OHD concentration. A slight majority (53%; κ = 19) of studies reported statistically significant associations between serum 25-OHD concentration and vitamin D knowledge and attitudes.Implications for Research and PracticeThe few educational interventions employed to increase serum 25-OHD concentration lack effectiveness. Future studies may use randomized controlled trial designs, enroll those at risk for vitamin D insufficiency and underrepresented in the literature, increase the salience of the information to the target population, and include safe sun exposure recommendations.     

Efficacy of daily and monthly high-dose calciferol in vitamin D-deficient nulliparous and lactating women

BACKGROUND: We previously found a high prevalence of vitamin D deficiency and low medication regimen compliance in Arab and East Indian women residing in the United Arab Emirates (UAE). The appropriate dosing regimen for improving vitamin D status in this population is not known. OBJECTIVE: We aimed to determine the efficacy of daily and monthly supplementation with vitamin D2, the only high-dose calciferol available in the UAE, in lactating and nulliparous women. DESIGN: Healthy lactating (n = 90) and nulliparous (n = 88) women were randomly assigned to consume 2000 IU vitamin D2/d or 60,000 IU vitamin D2/mo for 3 mo. Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured by radioimmunoassay at baseline and every month. RESULTS: Most women had vitamin D deficiency [ie, 25(OH)D < 50 nmol/L] at study entry. Mean +/- SD 25(OH)D concentrations at 3 mo were significantly higher than baseline in both lactating (39.8 +/- 12.4 and 25.2 +/- 10.7 nmol/L, respectively) and nulliparous (40.4 +/- 23.4 and 19.3 +/- 12.2 nmol/L, respectively) women (P < 0.001 for both). In total, vitamin D supplementation was effective in achieving serum 25(OH)D concentrations of >or=50 nmol/L in 21 (30%) of 71 women at endpoint. CONCLUSIONS: Oral vitamin D2 supplementation with 2000 IU/d or 60,000 IU/mo for 3 mo was safe, and it increased serum 25(OH)D concentrations significantly; however, only a small proportion of the women studied achieved concentrations of >or=50 nmol/L. This suggests that, when sunlight exposure is limited, doses of vitamin D2 higher than those currently studied may be needed. Monthly dosing appears to be a safe and effective alternative to daily dosing.