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.     

Heliotherapy improves vitamin D balance and atopic dermatitis

Background Vitamin D insufficiency during winter is common in the Nordic countries. Heliotherapy (HT) may heal atopic dermatitis (AD) but its effect on vitamin D balance has not been examined. Objectives To study the effect of HT on serum calcidiol (25‐hydroxyvitamin D) concentration and on healing of AD. Methods Twenty‐three adult patients with AD received a 2‐week course of HT in the Canary Islands in either January or March 2005. Daily solar ultraviolet (UV) radiation was measured and personal UV exposure calculated as standard erythema doses (SED). Blood samples were taken during HT and during a 1–2 month follow‐up. Serum calcidiol concentration was measured by radioimmunoassay. Healing of AD was examined by SCORAD index. Results Before HT 17 (74%) AD patients had vitamin D insufficiency (calcidiol < 50 nmol L^?1) and four patients high (> 80 nmol L^?1) serum calcidiol values. The median personal UV dose during the 2‐week HT course was 60 SED in the January group and 109 SED in the March group. Serum calcidiol concentration increased significantly in both groups, by 13·4 and 24·0 nmol/L^?1, respectively, and after HT only four (17%) patients had vitamin D insufficiency. SCORAD improved from 34 to 9 in the January HT group and from 30 to 9 in the March group. Conclusions A 2‐week course of HT significantly improved vitamin D balance by increasing serum calcidiol concentration, and caused a marked healing of AD. These parallel positive responses should be taken into account when the benefits of HT are considered.     

High dietary phosphate intake reduces bone strength in the growing rat skeleton.

Nutrition influences peak bone mass development in early adulthood. The effect of high dietary phosphate intake on the growing skeleton of 1-month-old male rats (n = 30) was assessed in an 8-week intervention. High dietary phosphate intake increased bone remodeling and impaired bone material properties, diminishing bone mechanical strength. INTRODUCTION: High dietary phosphate intake is typical in the Western diet. Abundant phosphate intake enhances parathyroid secretion and bone metabolism. To study the influence of high dietary phosphate intake on growing bone homeostasis and structure, we submitted growing rats to experimental diets that varied in their phosphate content. MATERIALS AND METHODS: One-month-old intact male rats (n = 30) were fed a control diet (Ca:P 1:1) or an experimental diet of either Ca:P 1:2 or Ca:P 1:3 for 8 weeks. At the beginning and the end of the study period, the right femurs were measured using DXA. Double labeling with tetracycline injection was performed 12 and 2 days before death. After death, hind legs were cut loose. Left femurs were processed for histomorphometry. Right femurs were measured with pQCT. Mechanical testing was performed on the right femoral neck and tibial shaft. Six right tibias were analyzed with microCT. Serum PTH, calcium, and phosphate contents were analyzed. RESULTS: High-phosphate intake impaired growth of the animal, limited bone longitudinal growth, and restricted femur BMC and BMD build-up. Osteoclast number, osteoblast perimeter, and mineral apposition rate were increased, and trabecular area and width were decreased. Phosphate decreased femur midshaft total bone BMD, cortical bone BMD, and mean cortical thickness. High-phosphate diet reduced femoral neck and tibial shaft ultimate strength and tibia stiffness and toughness. In addition, serum PTH increased. CONCLUSIONS: High dietary phosphate intake reduced growth, skeletal material, and structural properties and decreased bone strength in growing male rats. Adequate calcium could not overcome this.     

Hypercalciuria and kidney function in children with haemophilia

Adults with haemophilia have a higher incidence of chronic kidney disease than general male population. We recently showed that children with haemophilia have higher urinary calcium excretion and lower whole body bone mineral density than controls in spite of prophylaxis with the deficient coagulation factor concentrate, serum vitamin D concentrations comparable to those of healthy children and physically active lifestyle. Persistent hypercalciuria may result in nephrocalcinosis and impact renal function. This study sought to assess persistence of urinary calcium excretion and kidney function in children with haemophilia. We investigated retrospectively urinary calcium excretion in 30 children with haemophilia (mean age 12.5 years) from consecutive urine samples over a 2‐year period. Renal evaluation included blood and urine specimen, blood pressure, and renal ultrasound. High number of children with haemophilia had intermittent hypercalciuria. Hypercalciuria was not associated with age, severity of haemophilia or previous hypercalciuria. Kidney function and renal ultrasound were normal with the exception of suspected kidney stone in one patient with haemophilia and transient hypercalciuria. Vitamin D concentrations improved after the families had received information and recommendations concerning vitamin D substitution. Our findings indicate that haemophilia per se predisposes to hypercalciuria which may in turn affect bone mineral content and kidney function. Whether childhood‐onset intermittent hypercalciuria contributes to hypertension and renal complications in adulthood remains to be elucidated in future studies.     

Narrowband ultraviolet B course improves vitamin D balance in women in winter

Background Vitamin D insufficiency is common in winter in the Nordic countries. Objectives  To examine whether a short course of narrowband ultraviolet B (NB‐UVB) improves vitamin D balance. Methods Fifty‐six healthy, white women (mean age 41 years) volunteered and 53 completed the study. NB‐UVB exposures were given on seven consecutive days either on the whole body (n = 19), on the head and arms (n = 9) or on the abdomen (n = 14). Similarly, seven solar simulator exposures were given on the face and arms (n = 11). The cumulative UVB dose was 13 standard erythema doses in all regimens. Serum calcidiol (25‐hydroxyvitamin D) concentration was measured by radioimmunoassay before and after the NB‐UVB exposures. Follow‐up samples were taken from the whole‐body NB‐UVB group at 2 months. Results At onset 41 women (77%) had vitamin D insufficiency (calcidiol < 50 nmol L^?1) and six (11%) had vitamin D deficiency (calcidiol < 25 nmol L^?1). Calcidiol concentration increased significantly, by a mean of 11·4 nmol L^?1 when NB‐UVB was given on the whole body, by 11·0 nmol L^?1 when given on the head and arms and by 4·0 nmol L^?1 when given on the abdomen. Solar simulator exposures given on the face and arms increased calcidiol by 3·8 nmol L^?1. After 2 months serum calcidiol was still higher than initially in the group who received NB‐UVB exposures on the whole body. Conclusions NB‐UVB exposures given on seven consecutive days on different skin areas of healthy women significantly improved serum calcidiol concentration. A short low‐dose NB‐UVB course can improve vitamin D balance in winter.     

Strategies to improve vitamin D status in northern European children: exploring the merits of vitamin D fortification and supplementation

Adequacy of vitamin D in children in Europe has been the focus of a number of investigations. The results of measuring serum levels of 25-hydroxyvitamin D show high prevalence of vitamin D deficiency during the winter with lower prevalence during the summer. National policies on food fortification or individual supplementation with vitamin D have been recently revisited by the individual countries and the European Union as a whole. Optiford is a project managed by a coalition of scientists formed to optimize vitamin D fortification in the northern European Countries, was given the task to decide if food fortification with vitamin D is feasible and to provide a scientific basis for setting the vitamin D fortification level in Europe. This article presents the results of these investigations to date, with particular attention to potential corrective strategies to allow children and adolescents living in countries at high latitudes to maintain healthy circulating 25-hydroxyvitamin D levels year around, even in the absence of adequate sun exposure during a significant part of the year.