Vitamin D supplements and 25-hydroxy vitamin D concentrations in the elderly.

Serial 25-hydroxy vitamin D (25-OHD) concentrations were measured in long-stay geriatric patients treated with vitamin D. Comparison between a treatment and a control group showed that a daily dose of 500 IU vitamin D produced a significant increase in 25-OHD levels by two months. The supplement had a striking effect when the initial 25-OHD level was low and very little effect when it was high. 25-OHD levels in subjects on 2000 IU vitamin D daily were only marginally higher than those in subjects on 500 IU. A dose of 500 IU vitamin D daily should therefore produce adequate blood 25-OHD concentrations in most old people, and probably prevent most cases of osteomalacia in the elderly--though a large-scale study is needed to confirm this.     

Vitamin D (25OHD) Serum Seasonality in the United States

Background

Vitamin D is an important micronutrient for health. Hypovitaminosis D is thought to play a role in the seasonality of a number of diseases and adverse health conditions. To refine hypotheses about the links between vitamin D and seasonal diseases, good estimates of the cyclicality of serum vitamin D are necessary.

Objectives

The objective of this study is to describe quantitatively the cyclicality of 25-hydroxyvitamin D (25OHD) in the United States. We provide a statistical analysis with weekly time resolution, in comparison to the quarterly (winter/spring/summer/fall) estimates already in the literature.

Methods

We analyzed time series data on 25OHD, spanning 287 consecutive weeks. The pooled data set comes from 3.44 million serum samples from the United States. We statistically analyzed the proportion of sera that were vitamin D sufficient, defined as 25OHD ng/mL, as a function of date.

Results

In the United States, serum 25OHD follows a lagged pattern relative to the astronomical seasons, peaking in late summer (August) and troughing in late winter (February). Airmass, which is a function of solar altitude, fits the 25OHD data very well when lagged by 8 weeks.

Conclusions

Serum vitamin D levels can be modeled as a function of date, working through a double-log transformation of minimal solar airmass (easily calculated from solar altitude, retrievable from an online solar altitude/azimuth table).     

25OHD, a circulating vitamin D metabolite in fish.

Serum and hepatic 25-hydroxyvitamin D (25OHD), and serum calcium, phosphate, 25OHD₃ binding capacity and binding affinity were measured in male and female trout. Both serum and hepatic 25OHD levels are decreased in female trout with elevations in protein bound calcium and phosphate. Whereas the apparent dissociation constant (Kd) for serum binding of 25OHD₃ of 1.0–2.0 × 10^?9M is similar in males and females, the 25OHD₃ binding capacity of hypercalcemic spawning trout (1.39 × 10^?7M) is significantly less than that of male fish (1.88 × 10^?7M). At circulating serum concentrations of 25OHD which average 9.5 × 10^?9M only 5–7% of trout serum 25OHD binding sites are occupied.     

Vitamin D in adipose tissue and serum 25-hydroxyvitamin D after roux-en-Y gastric bypass

Vitamin D is stored in body fat. The purpose of this study was to determine vitamin D concentration in abdominal fat of obese patients who underwent roux‐en‐Y gastric bypass (RYGB), and to describe changes in serum 25‐hydroxyvitamin D (25(OH)D) levels in relation to loss of body fat. Subjects from a single clinic who were scheduled for RYGB were invited into the study. Abdominal subcutaneous, omental, and mesenteric fat were obtained at time of surgery. Adipose vitamin D₂ and vitamin D₃ concentrations were measured by high‐performance liquid chromatography (HPLC). Weight and serum 25(OH)D were assessed at baseline and every 3 months up to 1 year. Seventeen subjects were included, and fat samples were available from eleven. Total vitamin D content in subcutaneous abdominal fat was 297.2 ± 727.7 ng/g tissue, and a wide range was observed (4–2,470 ng/g). Both vitamin D₂ and vitamin D₃ were detected in some of the fat samples. At baseline, 25(OH)D was 23.1 ± 12.6 ng/ml. Average weight loss was 54.8 kg at 12 months, of which ～40 kg was fat mass. Despite daily vitamin D intake of ≥2,500 IU throughout the study, no significant increase in serum 25(OH)D was observed, with mean serum concentration of 25(OH)D at 1 year of 26.2 ± 5.36 ng/ml (P = 0.58). We conclude that vitamin D in adipose tissue does not significantly contribute to serum 25(OH)D despite dramatic loss of fat mass after RYGB.     

Summer/winter differences in the serum 25-hydroxyvitamin D3 and parathyroid hormone levels of Japanese women

Serum 25-hydroxyvitamin D₃ [25(OH)D₃] is produced in the skin in response to exposure to ultraviolet radiation, and is a good indicator of vitamin D nutritional status. The aim of this study was to determine summer/winter differences in serum 25(OH)D₃ and parathyroid hormone (PTH) in Japanese women and how the summer and winter values are related. The subjects were 122 healthy Japanese women aged 45–81 years (average age: 65.7 years). They were medically examined twice, in September 1997 and February 1999. Serum 25(OH)D₃ and intact PTH were determined by high-performance liquid chromatography and a two-site immunoradiometric assay respectively. Lifestyle information was obtained through an interview. The seasonal differences (winter minus summer) in 25(OH)D₃ [Δ25(OH)D₃] and intact PTH concentrations were –18.8 nmol/l (SD 19.2, P<0.0001) and 0.98pmol/l (SD 1.02, P<0.0001) respectively. The correlation coefficient between summer (x) and winter (y) 25(OH)D₃ levels was 0.462 (P<0.0001), with a linearly fitted line of y=0.42x+26.4. This relationship was interpreted as subjects with higher summer 25(OH)D₃ values having greater reductions in winter 25(OH)D₃ concentrations. There were inter-individual differences in Δ25(OH)D₃, although the summer and winter 25(OH)D₃ concentrations were well-correlated. Since Δ25(OH)D₃ was not associated with any of the lifestyle factors, seasonal differences in the 25(OH)D₃ concentrations of an individual appeared to reflect her ability to produce 25(OH)D₃ photochemically in the skin. Sun bathing would be a less effective means of attaining adequate vitamin D nutritional status in a person with a small seasonal difference in 25(OH)D₃, i.e., one with a low 25(OH)D₃ level. Received: 17 December 1999 / Revised: 24 April 2000 / Accepted: 10 May 2000     

Effect of phototherapy on serum 25-hydroxyvitamin D in the Antarctic

The hypothesis that sunlight may induce the enzymes involved in the vitamin D pathway has been tested by comparing the ability to synthesize vitamin D3 and its 25 hydroxy metabolite (25-OHD) in 2 groups of male volunteers resident at the British Antarctic base at Rothera Point (67 degrees 34'S.). One group endured the UV depleted winter and the other group received regular phototherapy throughout the winter. Both groups then received a course of 14 days phototherapy in October (Southern Hemisphere spring). The group receiving regular phototherapy had a trend towards a higher level of serum 25-OHD, and the October phototherapy course produced a further small increase in serum 25-OHD values. In the previously non irradiated group the October phototherapy produced a much larger increase in serum 25-OHD so that they attained the previously higher values of the pre-iradiated group. There was a negative correlation between the pre October phototherapy serum concentration of 25-OHD and the subsequent increment (r-0.78, p less than 0.01) but no relationship between the serum 25-OHD and D3 after phototherapy. These results provide evidence against the existence of enzyme induction of vitamin D 25 hydroxylase by light.     

Effect of vitamin D3 administration on serum 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3 and osteocalcin in vitamin D-deficient elderly people

In elderly institutionalized people, confined to bedroom and receiving no vitamin D supplementation, the frequency of vitamin D deficiency is found very high. Systematic administration of vitamin D has, therefore, been proposed to correct vitamin D deficiency. Within this context, we studied 40 elderly institutionalized subjects (mean age 80.5 + 7.2 yr) with low 25(OH)D3 concentrations (4.4 + 1.8 micrograms/l). Sixteen of them (Group I) had low serum calcium concentrations (less than 2.3 mmol/l) and 24 (Group II) had normal serum calcium concentrations (from 2.3 to 2.6 mmol/l). As hypocalcemia has been shown to regulate 1,25(OH)D3 production independent of PTH in animals and in humans, we compared their respective responses to the administration of vitamin D3. Subjects received a total dose of 15 mg (600,000 IU) of vitamin D3 divided into 3 i.m. injections at one month intervals and were explored before therapy and one and 6 months after the last dose of vitamin D3. The treatment induced a similar marked rise in 25(OH)D3 levels (from 4.1 + 1.7 to 24.4 + 8.7 micrograms/l for group I and from 5.1 + 1.8 to 27.2 + 8.0 micrograms/l for group II) in both groups but increased the 1,25(OH)2D3 concentrations only in group I (from 22.9 + 6.9 to 32.6 + 11.3 ng/l). Meanwhile serum calcium concentrations rose in group I (to low normal range i.e. 2.31 + 0.07 mmol/l) and were unaffected in group II. These results suggest that hypocalcemia is a potent stimulator of renal 1-hydroxylase in elderly people. Furthermore, a transient significant (P less than 0.01) increase in serum osteocalcin (from 10.6 + 4.1 to 14.1 + 5.9 micrograms/l) could be observed in group I which demonstrates for the first time that the osteocalcin response of osteoblasts to stimulation by 1,25(OH)2D3 is retained in very old people.     

Elevated serum 25(OH)D concentrations, vitamin D, and calcium intakes are associated with reduced adipocyte size in women

Recent studies have suggested a beneficial effect of vitamin D and calcium on adipocyte metabolism and the metabolic profile. Our objective was to examine associations of vitamin D intake, calcium and dairy products as well as serum 25(OH)D concentration with adiposity measures and adipocyte size in women. Omental and subcutaneous adipose tissue samples were obtained from 43 women undergoing gynecological surgeries. Adipocyte size was measured using adipocyte suspensions from collagenase-digested fat tissues. Total and visceral adiposity were assessed by dual-energy X-ray absorptiometry and computed tomography, respectively. Serum 25(OH)D was measured by radioimmmunoassay. Dietary intakes were assessed using a food frequency questionnaire. Women consuming two or more dairy product portions daily had smaller adipocytes in the omental depot compared to women consuming less than two portions daily (79 ± 12 vs. 94 ± 16 μm, P ≤ 0.01). Dietary intakes of calcium (r = -0.55) and vitamin D (r = -0.43) as well as serum 25(OH)D (r = -0.35) were also inversely and significantly associated with omental adipocyte size (P ≤ 0.05 for all). Dietary vitamin D intake was inversely associated with visceral adipose tissue area (r = -0.34, P ≤ 0.05). Serum 25(OH)D was also inversely associated with visceral adipose tissue area (r = -0.32) as well as with total adipose tissue area (r = -0.44), subcutaneous adipose tissue area (r = -0.36), BMI (r =-0.43) and total body fat mass (r = -0.41, P ≤ 0.05 for all). In conclusion, elevated dietary vitamin D intake and serum 25(OH)D values are related to lower visceral adiposity and omental adipocyte size in women.     

Changes of total content of serum magnesium in elderly Chinese women with osteoporosis

Objective To explore whether the serum levels of magnesium (Mg) and calcium (Ca) differ between osteoporotic and nonosteoporotic elderly Chinese women. Methods Using WHO classification criteria based on bone mineral density (BMD), general healthy Chinese women older than 65 yr were classified as osteoporosis (OP), osteopenia, and normal group according to the T-score of the femur neck. Then their physical characteristics, serum levels of magnesium (sMg), calcium (sCa), and other biochemical measurements were analyzed. Results Altogether, 324 subjects were included in the final analysis with 77 in OP, 137 in osteopenia, 110 in normal group. The level of sMg in women with OP is significantly higher (0.91±0.11 mmol/L) than both the osteopenia (0.88±0.09 mmol/L) and the normal (0.87±0.08 mmol/L) even after being adjusted for both age and body mass index (BMI), which might result from potentially low levels of sCa. sMg inversely related to sCa in subjects with OP (r=−0.240, p=0.038), whereas the total levels of sCa and sMg kept relatively steady. Conclusion High content of sMg and potentially low content of sCa could be a feature of the serum profile of elderly Chinese women with OP, the clinical significance of which needs further elucidation. Supplementation of Mg for elderly Chinese women with OP did not appear to be necessary.     

Parathyroid hormone and 25-hydroxyvitamin D concentrations in sick and normal elderly people.

Serum 25-hydroxyvitamin D and immunoreactive parathyroid hormone concentrations were measured in normal elderly subjects living at home and in sick elderly patients in hospital. Normal old people tended to have high 25-hydroxyvitamin D and low parathyroid hormone concentrations; in the sick elderly this pattern was reversed. The raised serum parathyroid hormone concentrations in the sick elderly were not due to poor renal function and may have been a response to vitamin D deficiency. A high serum parathyroid hormone concentration in an elderly patient must be interpreted in the light of the patient''s general health and nutritional state. Caution is needed in diagnosing primary hyperparathyroidism in this age group.     

Bone density parathyroid hormone and 25-hydroxyvitamin D concentrations in middle aged women.

OBJECTIVE--To examine the relation between bone density and indices of calcium metabolism including parathyroid hormone and 25-hydroxyvitamin D concentrations in middle aged women. DESIGN--A cross sectional study. SETTING AND SUBJECTS--138 women volunteers aged 45-65 with no known osteoporosis and unselected for disease status recruited for a dietary assessment study from the community using general practice registers. Volunteer rate was 20%. MAIN OUTCOME MEASURE--Bone mineral density measured with dual energy x ray absorptiometry. RESULTS--Bone density at the lumbar spine and neck and trochanteric regions of the femur was inversely related to serum intact parathyroid hormone concentrations and positively related to serum 25-hydroxyvitamin D concentrations. These associations were independent of possible confounding factors, including age, body mass index, cigarette smoking habit, menopausal status, and use of diuretics and postmenopausal hormone replacement therapy. These associations were apparent throughout the whole distribution of bone density and 25-hydroxyvitamin D and parathyroid hormone concentrations within the normal range, suggesting a physiological relation. CONCLUSIONS--The findings are consistent with the hypothesis that parathyroid hormone and 25-hydroxyvitamin D concentrations influence bone density in middle aged women. Findings from this study together with other work suggest that the role of vitamin D in osteoporosis should not be neglected. The associations with parathyroid hormone also indicate plausible biological mechanisms. The roughly 5-10% difference in bone density between top and bottom tertiles of serum 25-hydroxyvitamin D concentrations, though not large in magnitude, may have considerable public health implications in terms of prevention of osteoporosis and its sequelae, fractures.     

Vitamin D and fractures in the elderly

Osteoporosis and the subsequent fractures caused by this are a source of morbidity and mortality in the elderly population. It is also often the start of the cascade that culminates in frailty and dependence. Vitamin D has a direct relationship with the appearance of osteoporosis and with the risk of fractures. Receptors of this vitamin have also recently been described in other organs and systems of the body that are associated with muscle strength, cancer and overall mortality. Deficiency of this vitamin in the elderly population in Spain is very prevalent, both in the community and the hospitalised elderly. The diagnosis and treatment are straightforward and cheap. Its efficacy in the prevention of osteoporosis and in the appearance of fractures is perfectly demonstrated. In this review, we will look at the physiology and actions of this vitamin, as well as the principal studies that have demonstrated its effectiveness in the elderly population.     

Pre-diagnostic plasma 25-hydroxyvitamin D levels and risk of non-melanoma skin cancer in women

Background

Recent reports have shown that vitamin D status was inversely associated with the risk of various cancers. However, few studies examined the association between vitamin D levels and risk of skin cancer.

Methods

We prospectively evaluated the association between baseline plasma 25(OH)D levels and the risk of incident squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) among 4,641 women from the Nurses’ Health Study (NHS) and the NHS II with 510 incident BCC cases and 75 incident SCC cases. We used multivariate logistic regression models to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Plasma 25(OH)D levels were positively associated with risk of BCC after adjusting for age at blood draw, season of blood draw, lab batch, hair color, burning tendency, the number of sunburns, and ultra-violet B flux of residence at blood collection. Women in the highest quartile of 25(OH)D had more than 2-fold increased risk of BCC compared with women in the lowest quartile (OR = 2.07, 95% CI = 1.52–2.80, P for trend <0.0001). We also found a significantly positive association between plasma 25(OH)D levels and SCC risk after adjusting for the same covariates (OR, highest vs. lowest quartile  = 3.77, 95% CI = 1.70–8.36, P for trend  = 0.0002).

Conclusion

In this prospective study of women, plasma vitamin D levels were positively associated with non-melanoma skin cancer risk. Considering that most circulating vitamin D is due to sun exposure, the positive association between plasma vitamin D and non-melanoma skin cancer is confounded by sun exposure. Our data suggest that one-time measurement of plasma vitamin D levels may reasonably reflect long-term sun exposure and predict the risk of non-melanoma skin cancer.     

Treatment with 50000 IU Vitamin D2 Every Other Week and Effect on Serum 25-Hydroxyvitamin D2, 25-Hydroxyvitamin D3, and Total 25-Hydroxyvitamin D in Aclinical Setting

ObjectiveTo examine the effect of 50 000 IU-vitamin D₂ supplementation in a clinical setting on serum total 25-hydroxyvitamin D (25[OH]D), 25-hydroxyvitamin D₂ (25[OH]D₂), and 25-hydroxyvitamin D₃ (25[OH]D₃).MethodsThis retrospective cohort study was performed in an urban tertiary referral hospital in Boston, Massachusetts. Patients who had been prescribed 50 000 IU vitamin D₂ repletion and maintenance programs were identified through a search of our electronic medical record. Baseline and follow-up total serum 25(OH)D, 25(OH)D₂, and 25(OH)D₃ levels were compared.ResultsWe examined the medical records of 48 patients who had been prescribed 50 000 IU vitamin D₂ in our clinic. Mean ± standard deviation baseline total 25(OH) D was 31.0 ± 10.6 ng/mL and rose to 48.3 ± 13.4 ng/mL after treatment (P <.001). 25(OH)D₂ increased from 4.2 ± 4.3 ng/mL to 34.6 ± 12.3 ng/mL after treatment (P <.001), for an average of 158 days (range, 35-735 days). Serum 25(OH)D3 decreased from 26.8 ± 10.8 ng/mL to 13.7 ± 7.9 ng/mL (P <.001).ConclusionsFifty thousand IU vitamin D₂ repletion and maintenance therapy substantially increases total 25(OH)D and 25(OH)D2 despite a decrease in serum 25(OH)D3. This treatment program is an appropriate and effective strategy to treat and prevent vitamin D deficiency.(Endocr Pract. 2012;18:399-402)