Heli Viljakainen

A Positive Dose–Response Effect of Vitamin D Supplementation on Site-Specific Bone Mineral Augmentation in Adolescent Girls: A Double-Blinded Randomized Placebo-Controlled 1-Year Intervention†

The effect of vitamin D supplementation on bone mineral augmentation in 212 adolescent girls with adequate calcium intake was studied in a randomized placebo‐controlled setting. Bone mineral augmentation determined by DXA increased with supplementation both in the femur and the lumbar vertebrae in a dose‐responsive manner. Supplementation decreased the urinary excretion of resorption markers, but had no impact on formation markers.

UK Food Standards Agency Workshop Consensus Report: the choice of method for measuring 25-hydroxyvitamin D to estimate vitamin D status for the UK National Diet and Nutrition Survey

The consensus workshop, organised on behalf of the Food Standards Agency, was convened to recommend the most appropriate and secure method for measuring vitamin D status in the UK. Workshop participants (the Expert Panel) were invited on the basis of expertise in current 25-hydroxyvitamin D (25OHD) assays, or expertise in vitamin D nutrition and metabolism or detailed knowledge and experience in the National Diet and Nutrition Survey (NDNS). A decision support matrix, which set out the particular criteria by which the different options were scored and evaluated, was used to structure the discussion. The Expert Panel agreed that five methods for measuring 25OHD should be evaluated according to eleven criteria, selected on the basis of their relevance to the NDNS. All three of the evaluating subgroups of the Expert Panel produced similar total scores over the eleven criteria for the different methods; they scored LC-MS/MS and HPLC-UV similarly highly, while the scores for the immunoassay methods were lower. The Expert Panel recommended that an LC-MS/MS method should be the preferred method for the NDNS. A detailed specification for the method will be required to ensure comparability between NDNS and the National Health and Nutrition Examination Survey in the US facilitating future comparisons. The Expert Panel also recommended that the method should be carried out in a laboratory with appropriate expertise, competency and history of records of good performance. The method should be standardised against the National Institute of Standards and Technology SRM 972. If the recommended LC-MS/MS is adopted, the Expert Panel indicated that the method should be able to discriminate the C-3 epimer of 25OHD(3), especially if used to measure 25OHD in young infants in the forthcoming Diet and Nutrition Survey of Infants and Young Children, who are known to have high circulating concentrations of the C-3 epimer.

Habitual high phosphorus intakes and foods with phosphate additives negatively affect serum parathyroid hormone concentration: a cross-sectional study on healthy premenopausal women.

OBJECTIVE Foods can contain natural phosphorus (NP) and phosphate-containing food additives (AP). The main objective of the present study was to investigate whether NP and AP of habitual diets differ in their effects on markers of Ca metabolism. We also investigated the impact of total habitual dietary P intake on markers of Ca metabolism. DESIGN Cross-sectional study. Fasting blood samples were collected and participants kept a 4 d food record, from which dietary intake of total P and the consumption of NP (milk and cheese, excluding processed cheese) and AP (processed cheese) sources were calculated. Participants were divided into groups according to their NP- and AP-containing food consumption and into quartiles according to their total P intake. SETTING Southern Finland. SUBJECTS One hundred and forty-seven healthy premenopausal women aged 31-43 years. RESULTS Relative to the lowest total dietary P quartile, mean serum parathyroid hormone (S-PTH) concentration was higher (P = 0.048, analysis of covariance (ANCOVA)) and the mean serum ionized Ca concentration lower (P = 0.016, ANCOVA) in the highest P intake quartile. Mean S-PTH concentrations were higher among participants who consumed processed cheese (P = 0.027, ANCOVA) and less milk and other cheese than processed cheese (P = 0.030, ANCOVA). CONCLUSIONS High total habitual dietary P intake affected S-PTH unfavourably. Furthermore, phosphate additives may have more harmful effects on bone than other P sources, as indicated by higher mean S-PTH concentration among participants who consumed AP-containing foods. Because of the high dietary P intake and current upward trend in consumption of processed foods in Western countries, these findings may have important public health implications.

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 μg 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 μg: by 10.9 (8.5) nmol/L, 10 μg: by 14.4 (6.9) nmol/L, 20 μg: 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 μg 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.

Estimation of the dietary requirement for vitamin D in healthy adolescent white girls

BACKGROUND Knowledge gaps have contributed to considerable variation (between 0 and 15 μg/d) in international dietary recommendations for vitamin D in adolescents. OBJECTIVE We aimed to establish the distribution of dietary vitamin D required to maintain serum 25-hydroxyvitamin D [25(OH)D] concentrations above several proposed cutoffs (25, 37.5, 40, and 50 nmol/L) during wintertime in adolescent white girls. DESIGN Data (baseline and 6 mo) from 2 randomized, placebo-controlled, double-blind, 12-mo intervention studies in Danish (55°N) and Finnish (60°N) girls (n = 144; mean age: 11.3 y; mean vitamin D intake: 3.7 μg/d) at vitamin D(3) supplementation amounts of 0, 5, and 10 μg/d were used. Serum 25(OH)D was measured with an HPLC assay in a centralized laboratory. RESULTS Clear dose-related increments (P < 0.0001) in serum 25(OH)D with increasing supplemental vitamin D(3) were observed. The slope of the relation between vitamin D intake and serum 25(OH)D at the end of winter was 2.43 nmol ⋅ L(-1) ⋅ μg intake(-1), and no difference in the slopes between Finnish and Danish girls was observed. The vitamin D intakes that maintained serum 25(OH)D concentrations at >25, >37.5, and >50 nmol/L in 97.5% of the sample were 8.3, 13.5, and 18.6 μg/d, respectively, whereas an intake of 6.3 μg/d maintained a serum 25(OH)D concentration >40 nmol/L in 50% of the sample. CONCLUSION The vitamin D intakes required to ensure that adequate vitamin D status [defined variably as serum 25(OH)D >25 and >50 nmol/L] is maintained during winter in the vast majority (>97.5%) of adolescent girls (mean age: 11.3 y) at northern latitudes (>55°N) are 8.3 and 18.6 μg/d, respectively. This trial was registered at clinicaltrials.gov as NCT00267540.

Wintertime Vitamin D Supplementation Inhibits Seasonal Variation of Calcitropic Hormones and Maintains Bone Turnover in Healthy Men

Vitamin D is suggested to have a role in the coupling of bone resorption and formation. Compared with women, men are believed to have more stable bone remodeling, and thus, are considered less susceptible to the seasonal variation of calcitropic hormones. We examined whether seasonal variation exists in calcitropic hormones, bone remodeling markers, and BMD in healthy men. Furthermore, we determined which vitamin D intake is required to prevent this variation. Subjects (N = 48) were healthy white men 21–49 yr of age from the Helsinki area with a mean habitual dietary intake of vitamin D of 6.6 ± 5.1 (SD) μg/d. This was a 6‐mo double‐blinded vitamin D intervention study, in which subjects were allocated to three groups of 20 μg (800 IU), 10 μg (400 IU), or placebo. Fasting blood samplings were collected six times for analyses of serum (S‐)25(OH)D, iPTH, bone‐specific alkaline phosphatase (BALP), and TRACP. Radial volumetric BMD (vBMD) was measured at the beginning and end of the study with pQCT. Wintertime variation was noted in S‐25(OH)D, S‐PTH, and S‐TRACP (p < 0.001, p = 0.012, and p < 0.05, respectively) but not in S‐BALP or vBMD in the placebo group. Supplementation inhibited the winter elevation of PTH (p = 0.035), decreased the S‐BALP concentration (p < 0.05), but benefited cortical BMD (p = 0.09) only slightly. Healthy men are exposed to wintertime decrease in vitamin D status that impacts PTH concentration. Vitamin D supplementation improved vitamin D status and inhibited the winter elevation of PTH and also decreased BALP concentration. The ratio of TRACP to BALP shows the coupling of bone remodeling in a robust way. A stable ratio was observed among those retaining a stable PTH throughout the study. A daily intake of vitamin D in the range of 17.5–20 μg (700–800 IU) seems to be required to prevent winter seasonal increases in PTH and maintain stable bone turnover in young, healthy white men.

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.

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.

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

Background  Vitamin D insufficiency is common in winter in the Nordic countries.

A seasonal variation of calcitropic hormones, bone turnover and bone mineral density in early and mid-puberty girls - a cross-sectional study.

The importance of the seasonal variation of calcitropic hormones to growing skeleton has not been established. We studied whether there exists a seasonal variation in calcitropic hormones, bone mineral density (BMD) and bone remodelling markers in early puberty girls. One hundred and ninety-six girls, mean age 11.4 (sd 0.4) years, in Tanner stage 2 (early puberty) and 3 (mid-puberty) were studied during September to March. The BMD was measured from the lumbar vertebrae and the left femur by dual-energy X-ray absoptiometry. Their serum 25-hydroxyvitamin D (S-25-OHD), serum intact parathyroid hormone (S-iPTH), serum osteocalcin, urinary pyridinoline and urinary deoxypyridinoline were analysed from fasting samples. The concentration of S-25-OHD and serum osteocalcin differed among months (P < 0.01), reflecting a seasonal variation. The parathyroid hormone correlated negatively with S-25-OHD (r -0.325, P < 0.001). Moreover, the BMD in the femur (P = 0.047) and to a lesser extent in vertebrae (P = 0.057) differed between months in early puberty girls but this was not seen in mid-puberty. Seasonal variation in S-25-OHD and bone remodelling markers accompanied by negative correlation between S-25-OHD and S-iPTH was seen in this cross-sectional study of adolescent girls. In addition, the seasonal rhythm contributed 7.0-7.6 % difference in the BMD of lumbar vertebrae and left femur in early puberty girls. This variation should be avoided since it could hamper peak bone mass attainment.