Relationship between Serum 25-Hydroxyvitamin D Level and Risk of Recurrent Stroke

Evidence for the association between vitamin D and risk of recurrent stroke remains sparse and limited. We aimed to assess the relationship between serum circulating 25-hydroxyvitamin D (25(OH)D) level and risk of recurrent stroke in patients with a stroke history, and to identify the optimal 25(OH)D level in relation to lowest recurrent stroke risk. Data from the nationwide prospective United Kingdom Biobank were used for analyses. Primary outcome was time to first stroke recurrence requiring a hospital visit during follow-up. We used Cox proportional hazards regression model with restricted cubic splines to explore 25(OH)D level in relation to recurrent stroke. The dose-response relationship between 25(OH)D and recurrent stroke risk was also estimated, taking the level of 10 nmol/L as reference. A total of 6824 participants (mean age: 60.6 years, 40.8% females) with a baseline stroke were included for analyses. There were 388 (5.7%) recurrent stroke events documented during a mean follow-up of 7.6 years. Using Cox proportional hazards regression model with restricted cubic splines, a quasi J-shaped relationship between 25(OH)D and risk of recurrent stroke was found, where the lowest recurrent stroke risk lay at the 25(OH)D level of approximate 60 nmol/L. When compared with 10 nmol/L, a 25(OH)D level of 60 nmol/L was related with a 48% reduction in the recurrent stroke risk (hazard ratio = 0.52, 95% confidence interval: 0.33–0.83). Based on data from a large-scale prospective cohort, we found a quasi J-shaped relationship between 25(OH)D and risk of recurrent stroke in patients with a stroke history. Given a lack of exploring the cause–effect relationship in this observational study, more high-quality evidence is needed to further clarify the vitamin D status in relation to recurrent stroke risk.     

Association between Intake of Sugar-Sweetened Beverages and Circulating 25-Hydroxyvitamin D Concentration among Premenopausal Women

Intake of sugar-sweetened beverages has increased in North America and seems to have several adverse health effects possibly through decreased circulating 25-hydroxyvitamin D (25(OH)D) concentrations. The aim of this cross-sectional study was to evaluate the association between sugar-sweetened beverages intake and 25(OH)D concentrations among premenopausal women. Intake of sugar-sweetened beverages including colas, other carbonated beverages and sweet fruit drinks was assessed using a validated food frequency questionnaire among 741 premenopausal women. Plasma concentrations of 25(OH)D were quantified by radioimmunoassay. The association between sugar-sweetened beverages intake and 25(OH)D concentrations was evaluated using multivariate generalized linear models and Spearman correlations. A higher intake of colas was associated with lower mean 25(OH)D levels (67.0, 63.7, 64.7 and 58.5 nmol/L for never, <1, 1–3 and >3 servings/week, respectively; r = −0.11 (p = 0.004)). A correlation was observed between intake of other carbonated beverages and 25(OH)D concentrations but was not statistically significant (r = −0.06 (p = 0.10)). No association was observed between intake of sweet fruit drinks and 25(OH)D concentrations. This study suggests that high intake of colas may decrease 25(OH)D levels in premenopausal women. Considering the high consumption of these drinks in the general population and the possible consequences of vitamin D deficiency on health, this finding needs further investigation.     

The Importance of Dose,Frequency and Duration of Vitamin D Supplementation for Plasma 25-Hydroxyvitamin D

The importance of dose, frequency and duration of vitamin D supplementation for plasma 25(OH)D levels is not well described and rarely reported for supplementation that exceeds 2000 IU per day. The objective is to examine dose, frequency and duration of supplementation in relation to plasma 25(OH)D in a large population-based sample. We accessed data on 2714 volunteers that contributed to 4224 visits and applied multilevel regression. Compared to not using supplements, a minimum regimen of 1000–2000 IU once or twice per week for one month was not effective in raising 25(OH)D. Compared to this minimum regimen, higher doses of 2000–3000, 3000–4000, and 5000 IU or more were associated with a 7.49, 13.19 and 30.22 nmol/L 25(OH)D increase, respectively; frequencies of three to four, five to six and seven times/week were associated with a 5.44, 16.52 and 30.69 nmol/L increase, respectively; and supplementation of five months or longer was associated with an increase of 6.68 nmol/L (p < 0.01 for all). Age, body weight, physical activity, smoking, and self-rated health were significantly associated with 25(OH)D. Whereas dose, frequency and duration of supplementation are important to healthy subjects committed to optimizing their nutritional status, to the design of clinical trials, individual characteristics and lifestyle contribute substantially to 25(OH)D.     

Plasma 25-Hydroxyvitamin D Responses of Younger and Older Men to Three Weeks of Supplementation with 1800 IU/day of Vitamin D

Objective: The objective of this study was to compare changes in plasma 25-hydroxyvitamin D (25(OH)D) levels of younger and older men after three weeks of oral vitamin D supplementation.

Methods: Nine younger men (22 to 28 years) and nine older men (65 to 73 years) with self-reported vitamin D intakes below 200 IU/d were enrolled in February and randomized to 1800 IU/d of ergocalciferol (vitamin D₂, n=11) or to a control group (n=7) and followed for three weeks. Blood was collected at baseline, and after one, two and three weeks for measurement of plasma concentrations of total 25(OH)D, 25(OH)D₂ and 25(OH)D₃.

Results: In both the younger and older supplemented men, 25(OH)D₂ and total 25(OH)D concentrations increased significantly during the study, whereas values of these metabolites did not change in younger or older control subjects. No group showed significant changes in 25-hydroxyvitamin D₃. There was a significant interaction between age group and supplement group, suggesting that the effect of vitamin D₂ supplementation on changes in 25(OH)D₂ changes with age. The mean increase in 25(OH)D₂ was greater in the younger supplemented men than in the older supplemented men (37±9 nmol/L vs. 19.5 nmol/L, p=0.027), and this accounted for their significantly greater increase in total 25(OH)D.

Conclusion: These data are consistent with an age-related decline in the absorption, transport or liver hydroxylation of orally-consumed vitamin D.     

Moderate Amounts of Vitamin D3 in Supplements are Effective in Raising Serum 25-Hydroxyvitamin D from Low Baseline Levels in Adults: A Systematic Review

There is controversy surrounding the designation of vitamin D adequacy as defined by circulating levels of the metabolite 25-hydroxyvitamin D (25(OH)D). Depending on the cutoff level chosen, dietary intakes of vitamin D may or may not provide sufficient impact upon vitamin D status measured as improvement in serum levels of 25(OH)D. We sought to examine whether modest daily doses (5–20 μg) as found in fortified foods or multivitamin supplements had a measureable impact on vitamin D status, defined as moving from below to above 50 nmol/L, or from less than 30 nmol/L to above 30 nmol/L. Published literature was searched for relevant articles describing randomized controlled trials. Exclusion criteria were: studies not involving humans; review articles; studies lacking blood level data pre- and post-treatment; no control group; bolus treatments (weekly, monthly, yearly); vitamin D <5 μg or >20 μg; baseline 25(OH)D ≥75 nmol/L; subjects not defined as healthy; studies <8 weeks; and age <19 years. Of the 127 studies retrieved, 18 publications with 25 separate comparisons met criteria. The mean rate constant, defined as change in 25(OH)D in nmol/L per μg vitamin D administered, was calculated as 2.19 ± 0.97 nmol/L per μg. There was a significant negative correlation (r = −0.65, p = 0.0004) between rate constant and administered dose. To determine impact of the dose reflecting the Estimated Average Requirement (EAR) of 10 μg administered in nine studies (10 comparisons), in every case mean 25(OH)D status rose either from “insufficient” (30–50 nmol/L) to “sufficient” (>50 nmol/L) or from “deficient” (<30 nmol/L) to “insufficient” (>30 but <50 nmol/L). Our study shows that when baseline levels of groups were <75 nmol/L, for every microgram of vitamin D provided, 25(OH)D levels can be raised by 2 nmol/L; and further, when groups were deficient or insufficient in vitamin D, there was significant value in providing additional 10 μg per day of vitamin D.     

Total,Bioavailable, and Free 25-Hydroxyvitamin D Equally Associate with Adiposity Markers and Metabolic Traits in Mexican Adults

Epidemiological studies suggest a relationship between total 25-hydroxyvitamin D [25(OH)D], adiposity, and metabolic traits. The bioavailability of 25(OH)D is regulated by the albumin, vitamin D binding protein (VDBP), and variants of the GC gene. Therefore, it is not clear if bioavailable or free 25(OH)D offer additional benefits compared to total 25(OH)D when estimating the magnitude of these associations. Our aim was to evaluate the association between 25(OH)D (total, free and bioavailable) with adiposity and metabolic traits. This was a cross-sectional study of 1904 subjects from the Health Workers Cohort Study from Mexico. Free and bioavailable 25(OH)D were calculated based on VDBP and albumin determinations, using a formula adjusted for the GC gene diplotypes. Adiposity and metabolic traits were measured with standardized procedures. Free and bioavailable 25(OH)D levels correlated with total 25(OH)D, r = 0.71 and 0.70, respectively (p < 0.001). Total, bioavailable and free 25(OH)D levels were negatively associated with the adiposity marker (visceral adiposity index) and metabolic traits (metabolic syndrome, type 2 diabetes, triglycerides, triglycerides/HDL-c ratio, and triglycerides/glucose index) in multivariate regression models (ORs = 0.73 to 0.96). Our findings suggest that free and bioavailable 25(OH)D do not offer additional advantages over total 25(OH)D regarding its association with adiposity and several metabolic traits in Mexican adults.     

25-Hydroxyvitamin D and Its Relationship with Autonomic Dysfunction Using Time- and Frequency-Domain Parameters of Heart Rate Variability in Korean Populations: A Cross-Sectional Study

Previous studies have demonstrated that reduced heart rate variability (HRV) and hypovitaminosis D are associated with cardiovascular disease (CVD). However, few reports have investigated the effects of vitamin D on HRV. This cross-sectional study analyzed serum 25-hydroxyvitamin D (25(OH)D) and HRV indices using 5-min R-R interval recordings with an automatic three-channel electrocardiography in healthy subjects (103 males and 73 females). Standard deviation of N-N interval (SDNN), square root of mean squared differences of successive N-N intervals (RMSSD), total power (TP), very low frequency (VLF), low frequency (LF), and high frequency (HF) were reported. The mean age of subjects was 55.3 ± 11.3 years and the mean 25(OH)D level was 21.2 ± 9.9 ng/mL. In a multiple linear regression model, 25(OH)D was positively correlated with SDNN (β = 0.240, p < 0.002), and LF (β = 0.144, p = 0.044). Vitamin D deficiency (25(OH)D < 15 ng/mL) was associated with decreased SDNN (<30 m/s) (OR, 3.07; 95% confidence interval (CI), 1.32–7.14; p = 0.014) after adjusting for covariates. We found that lower 25(OH)D levels were associated with lower HRV, suggesting a possible explanation for the higher risk of CVD in populations with hypovitaminosis D.     

The Association of Oral Contraceptive Use with Plasma 25-hydroxyvitamin D Levels

Objective: This analysis was conducted to compare wintertime 25-hydroxyvitamin D (25OHD) levels of young women who did and did not use oral contraceptives (OC).

Methods: The subjects were 66 Caucasian women aged 20 through 40 recruited from the Boston area. Plasma 25OHD was measured in February or March and again 1 year later. Other measurements included height, weight and vitamin D intake from diet and supplements.

Results: The initial mean 25OHD level of the 26 OC users was 41% higher than those of nonusers before adjustment for age and vitamin D intake (83±40 (sd) nmol/L compared with 59±22), and 39% higher after adjustment (p=0.003). Five women who discontinued OC use during the year following their initial measurement all had decreases in their 25OHD levels (mean change was ?25.5±17.7 (SD) nmol/L), whereas levels in women whose OC use or non-use was constant did not change.

Conclusion: OC use increases circulating levels of 25OHD, and should be considered when interpreting values obtained for clinical evaluatin or nutrition research.     

Comparison of Vitamin D and 25-Hydroxyvitamin D Concentrations in Human Breast Milk between 1989 and 2016–2017

Background: Breast milk is considered the optimal source of nutrition during infancy. Although the vitamin D concentration in human breast milk is generally considered poor for infants, vitamin D in breast milk is an important source for exclusively breastfed infants. Increases in vitamin D insufficiency and deficiency in lactating mothers may reduce vitamin D concentrations in breast milk. This study aimed to compare vitamin D and 25-hydroxyvitamin D (25OHD) concentrations in breast milk collected in 1989 and 2016–2017 and simultaneously analyze them with liquid chromatography-tandem mass spectrometry (LC-MS/MS); the association between the lifestyle of recent lactating mothers (2016–2017) and vitamin D status in human breast milk was also evaluated. Method: Lactating mothers were recruited from three regions of Japan in 1989 (n = 72) and 2016–2017 (n = 90), and milk from 3–4 months was collected in summer and winter. The samples were strictly sealed and stored at −80℃ until measurement. Breast milk vitamin D and 25OHD concentrations were analyzed by LC-MS/MS. Vitamin D intake, sun exposure, and sunscreen use of the lactating mothers in 2016–2017 were assessed. Results: Both vitamin D and 25OHD concentrations in breast milk were higher in the summer regardless of the survey year. Significantly lower vitamin D and 25OHD concentrations were observed in 2016–2017 compared with 1989 in summer, but no survey year difference was observed in winter. The stepwise multiple regression analyses identified season, daily outdoor activity, and suntan in the last 12 months as independent factors associated with vitamin D₃ concentrations. Conclusion: The results suggest that low vitamin D status in recent lactating mothers may have decreased vitamin D and 25OHD concentrations in breast milk compared with the 1980s. These results are helpful for developing public health strategies to improve vitamin D status in lactating mothers and infants.     

Prevalence and Predictors of Low Serum 25-Hydroxyvitamin D among Female African-American Breast Cancer Survivors

Background

African-American breast cancer survivors commonly demonstrate low serum 25-hydroxyvitamin D (25(OH)D). Decreased cutaneous conversion, high levels of adiposity, and even breast cancer treatment may influence vitamin D status. Previous investigations have analyzed African-American women in aggregate with other breast cancer survivors and have not comprehensively addressed these influential factors.

Serum 25-Hydroxyvitamin D Concentrations and Atopic Dermatitis in Early Childhood: Findings from the Japan Environment and Children’s Study

Vitamin D (VitD) may affect immune system modulation and result in the development of atopic dermatitis (AD). However, published findings have remained controversial. We investigated the association between early-life 25-hydroxyvitamin D (25(OH)D) levels and AD risk at childhood with a birth cohort. The data were obtained from “the Japan Environment and Children’s Study (JECS)” and “the Sub-Cohort study of JECS” performed with children aged 2 years. “Liquid chromatography-tandem mass spectrometry” was used to measure VitD. The information on AD was obtained from parents’ answers to a questionnaire when their children were aged 3 years. In order to explain the seasonal effects on VitD levels, a deseasonalized continuous variable was further calculated. The logistic regression models were fitted to evaluate the effect of VitD on childhood AD. The study included 4378 children with complete data on VitD and AD. The results from models indicated that low VitD at 2 years was not a risk factor for the development of AD at 3 years, after adjusting for potential confounders. Moreover, there was no U-shape relationship between deseasonalized VitD and childhood AD. Overall, early-life 25(OH)D levels were not link to the increased risk of developing childhood AD.     

Association between Subcutaneous White Adipose Tissue and Serum 25-Hydroxyvitamin D in Overweight and Obese Adults

Cholecalciferol is known to be deposited in human adipose tissue, but it is not known whether 25-hydroxyvitamin D (25(OH)D) is found in detectable concentrations. Therefore, our objective was to determine whether 25(OH)D is detectable in subcutaneous white adipose tissue (SWAT) in overweight and obese persons enrolled in a twelve week energy restricted diet. Baseline and post-intervention gluteal SWAT biopsies were collected from 20 subjects participating in a larger clinical weight loss intervention. LC-MS/MS was utilized to determine SWAT 25(OH)D concentrations. Serum 25(OH)D and 1,25(OH)₂D were measured by RIA. Body composition was assessed by dual energy x-ray absorptiometry. SWAT 25(OH)D concentrations were 5.8 ± 2.6 nmol/kg tissue and 6.2 ± 2.7 nmol/kg tissue pre- and post-intervention SWAT, respectively. There was a significant positive association between SWAT 25(OH)D concentration and serum 25(OH)D concentration (r = 0.52, P < 0.01). Both SWAT and serum 25(OH)D concentrations did not significantly change after a twelve-week period of energy restriction with approximately 5 kg of fat loss. In conclusion, we have demonstrated our LC-MS/MS method can detect 25(OH)D₃ in human subcutaneous fat tissue from overweight and obese individuals and is consistent with previously reported concentrations in swine. Additionally, our findings of no significant changes in SWAT 25(OH)D₃ or serum 25(OH)D after a 6% loss of total body weight and 13% reduction in total fat provides the first human evidence that adipose 25(OH)D does not likely contribute to serum 25(OH)D with moderate weight loss; whether this is also the case with larger amounts of weight loss is unknown. Weight loss alone is not sufficient to increase serum 25(OH)D and increases in dietary or dermal biosynthesis of vitamin D appear to be the most critical contributors to in vitamin D status.     

Association between Suboptimal 25-Hydroxyvitamin D Status and Overweight/Obesity in Infants: A Prospective Cohort Study in China

This study aimed to investigate whether 25-hydroxyvitamin D (25(OH)D) concentrations are correlated to overweight/obesity in infants and to explore a threshold of 25(OH)D. A total of 1205 six-month-old infants from two community hospitals in Shanghai were randomly recruited, and 925 of them were followed up at 12 months. Concentration of 25(OH)D, weight, and length were measured at two time points. Overweight/obesity was defined as a weight-for-length Z-score >97th percentile. The prevalence of overweight/obesity at 6 and 12 months was 6.88% and 5.26%, respectively. The occurrence of vitamin D (VitD) deficiency (<20 ng/mL) at 6 and 12 months was 6.56% and 2.05%, respectively. Concentration of 25(OH)D at the corresponding age was negatively associated with weight-for-length percentile (WLP) at both 6 (adjusted β: −0.14; 95% CI: −0.27, −0.02; p = 0.02) and 12 months (adjusted β: −0.22; 95% CI: −0.41, −0.02; p = 0.03), while the relationship between 25(OH)D at 6 months and WLP at 12 months was nonlinear, where 35 ng/mL was identified as an inflection point. Those with a concentration of 25(OH)D <35 ng/mL at 6 months had a higher risk of overweight/obesity (adjusted OR: 1.42; 95% CI: 1.06, 1.91; p = 0.02) compared to the group with a concentration of 25(OH)D ≥35 ng/mL. Moreover, a concentration of 25(OH)D <35 ng/mL at two time points significantly increased the risk of overweight/obesity at 12 months compared to the group with 25(OH)D concentration ≥35 ng/mL at two time points (adjusted OR: 2.91; 95% CI: 1.13, 7.46; p = 0.03). A suboptimal 25(OH)D concentration <35 ng/mL significantly increases the risk of overweight/obesity in infants.     

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.     

A Narrative Review of the Evidence for Variations in Serum 25-Hydroxyvitamin D Concentration Thresholds for Optimal Health

Vitamin D₃ has many important health benefits. Unfortunately, these benefits are not widely known among health care personnel and the general public. As a result, most of the world’s population has serum 25-hydroxyvitamin D (25(OH)D) concentrations far below optimal values. This narrative review examines the evidence for the major causes of death including cardiovascular disease, hypertension, cancer, type 2 diabetes mellitus, and COVID-19 with regard to sub-optimal 25(OH)D concentrations. Evidence for the beneficial effects comes from a variety of approaches including ecological and observational studies, studies of mechanisms, and Mendelian randomization studies. Although randomized controlled trials (RCTs) are generally considered the strongest form of evidence for pharmaceutical drugs, the study designs and the conduct of RCTs performed for vitamin D have mostly been flawed for the following reasons: they have been based on vitamin D dose rather than on baseline and achieved 25(OH)D concentrations; they have involved participants with 25(OH)D concentrations above the population mean; they have given low vitamin D doses; and they have permitted other sources of vitamin D. Thus, the strongest evidence generally comes from the other types of studies. The general finding is that optimal 25(OH)D concentrations to support health and wellbeing are above 30 ng/mL (75 nmol/L) for cardiovascular disease and all-cause mortality rate, whereas the thresholds for several other outcomes appear to range up to 40 or 50 ng/mL. The most efficient way to achieve these concentrations is through vitamin D supplementation. Although additional studies are warranted, raising serum 25(OH)D concentrations to optimal concentrations will result in a significant reduction in preventable illness and death.     

Circulating levels of vitamin D, vitamin D receptor polymorphisms, and colorectal adenoma: a meta-analysis

Growing evidence suggests an elevated risk for colorectal neoplasia among individuals with low levels of vitamin D, the biological actions of which are mediated by the vitamin D receptor (VDR). To investigate the association among vitamin D status, VDR polymorphisms (FokI, and BsmI), and colorectal adenoma, we conducted a meta-analysis of nine studies of circulating levels of 25-hydroxyvitamin D (25(OH)D) and five studies of FokI or BsmI polymorphisms in relation to colorectal adenomas. Study-specific relative risks (RRs) and 95% confidence intervals (CIs) were pooled using a random-effects model. A total of 3398 colorectal adenomas for 25(OH)D and 1754 colorectal adenomas for VDR were included in the meta-analysis. We identified a significant inverse association between colorectal adenoma (combined RR, 0.93; 95% CI, 0.87-0.98 per 10 ng/mL increase in 25(OH)D levels). When we examined FokI and BsmI polymorphisms in the meta-analysis, we found no association for either FokI (combined RR, 1.00; 95% CI, 0.95-1.06) or BsmI (combined RR, 0.99; 95% CI, 0.93-1.05) in the additive model. These data suggest an inverse association between circulating 25(OH)D levels and colorectal adenoma risk.     

25-Hydroxyvitamin D in Cancer Patients Admitted to Palliative Care: A Post-Hoc Analysis of the Swedish Trial ‘Palliative-D’

The purpose of this study is to explore 25-hydroxyvitamin D (25-OHD) levels in patients with cancer in the palliative phase in relation to season, sex, age, tumor type, colectomy, and survival. To this end, we performed a post-hoc analysis of ‘Palliative-D’, a randomized placebo-controlled, double-blind trial investigating the effect of daily supplementation with 4000 IU of vitamin D for 12 weeks on pain in patients in palliative cancer care. In the screening cohort (n = 530), 10% of patients had 25-OHD levels < 25 nmol/L, 50% < 50, and 84% < 75 nmol/L. Baseline 25-OHD did not differ between seasons or tumor type and was not correlated with survival time. In vitamin D deficient patients supplemented with vitamin D (n = 67), 86% reached sufficient levels, i.e., >50 nmol/L, after 12 weeks. An increase in 25-OHD was larger in supplemented women than in men (53 vs. 37 nmol/L, p = 0.02) and was not affected by season. In the placebo-group (n = 83), decreased levels of 25-OHD levels were noted during the study period for patients recruited during the last quarter of the year. In conclusion, cancer patients in palliative phase have adequate increase in 25-OHD after vitamin D supplementation regardless of season, age, tumor type, or colectomy.     

Association of Dietary Vitamin D Intake,Serum 25(OH)D3, 25(OH)D2 with Cognitive Performance in the Elderly

Background: As life expectancy increases, cognitive performance decline in the elderly has become one of the major global challenges. We aimed to evaluate the association of dietary vitamin D (VD), serum 25-hydroxyvitamin D3 (25(OH)D₃), 25-hydroxyvitamin D2 (25(OH)D₂), and total 25-hydroxyvitamin (25(OH)D) concentration with cognitive performance in older Americans. Methods: The data from the National Health and Nutrition Examination Survey (NHANES), 2011–2014 was used. The cognitive performance was assessed by the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) Word Learning sub-test, Animal Fluency test, and Digit Symbol Substitution Test (DSST). A binary logistic regression model was applied to evaluate the association between VD and cognitive performance, and restricted cubic spline model was adopted to evaluate the dose–response relationship. Results: While comparing to the lowest dietary VD intake group, the multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of the highest dietary VD intake group were 0.51 (0.36–0.72) for the Animal Fluency test score and 0.45 (0.31–0.66) for DSST score, respectively; and those of serum total 25(OH)D and 25(OH)D₃ concentration were 0.68 (0.47–0.97) and 0.62 (0.44–0.86) for DSST score. L-shaped relationships were identified for dietary VD intake, serum total 25(OH)D and 25(OH)D₃ concentration with cognition performance. The associations between dietary VD intake, serum total 25(OH)D and cognitive performance were non-significant when stratified by gender. Conclusions: The study indicates that dietary VD intake, serum total 25(OH)D and 25(OH)D₃ concentration were positively associated with cognitive performance. Further studies are needed to clarify the possible effects of dietary VD intake and serum 25(OH)D₂, 25(OH)D₃ on cognitive performance.     

Assessment of Vitamin D Status in Slovenian Premenopausal and Postmenopausal Women,Using Total,Free, and Bioavailable 25-Hydroxyvitamin D (25(OH)D)

The objective of our study was to evaluate vitamin D status and its predictors in Slovenian premenopausal and postmenopausal women. A cross-sectional study was carried out between 1 March 2021 and 31 May 2021. A total of 319 healthy women from the Central Slovenian region aged between 44 and 65 were recruited; 176 were included in the final analysis. The vitamin D status was determined by measuring the total 25-Hydroxycholecalciferol (25(OH)D) concentration, vitamin D binding protein (DBP), and albumin and calculating the bioavailable 25(OH)D and free 25(OH)D. For the calculation of bioavailable and free 25(OH)D, we developed a new online calculator. The Endocrine Society’s thresholds for vitamin D deficiency and insufficiency were used; 29.0% of premenopausal and 24.4% of postmenopausal subjects were found to be vitamin D deficient (total 25(OH)D < 50 nmol/L); 76.8% of the premenopausal and 61.7% of postmenopausal subjects were found to have insufficient levels (total 25(OH)D < 75 nmol/L). Premenopausal women had 11.8% lower total 25(OH)D, 32.2% lower bioavailable 25(OH)D, and 25.2% higher DBP than postmenopausal women. The most important predictors of vitamin D status were vitamin D supplementation and time spent in the sun. Contrary to similar studies, the vitamin D status in Slovenian postmenopausal women was significantly better than in premenopausal women. In postmenopausal women, the measurement of free or bioavailable 25(OH)D instead of the total 25(OH)D could be advantageous.     

Association Between Serum 25(OH)D Level and Nonspecific Musculoskeletal Pain in Acute Rehabilitation Unit Patients

Objective: Nonspecific musculoskeletal pain can be difficult to manage in acute rehabilitation unit (ARU) patients. We investigated whether vitamin D status is a potential modifiable risk factor for nonspecific musculoskeletal pain in ARU patients. Materials and Methods: This cross‐sectional study focused on 414 adults from an inpatient ARU in Mission Viejo, California, between July 2011 and June 2012. On ARU admission, all patients had serum 25‐hydroxyvitamin D (25(OH)D) levels measured and were assessed for nonspecific musculoskeletal pain. We performed multivariable logistic regression to test the association of serum 25(OH)D level with nonspecific musculoskeletal pain while adjusting for clinically relevant covariates. Results: Among these 414 patients, mean (SD) 25(OH)D level was 29 (12) ng/mL, and 30% had nonspecific musculoskeletal pain. After adjustment for age, sex, race, body mass index, Functional Independence Measure score, Deyo‐Charlson Comorbidity Index, fractures, steroid use, history of osteoporosis/osteomalacia, and patient type (orthopedic, cardiac, neurological, spinal cord injury, or traumatic brain injury), serum 25(OH)D level was inversely associated with nonspecific musculoskeletal pain (odds ratio [OR] per 10 ng/mL, 0.67; 95% confidence interval [CI], 0.48–0.82). When 25(OH)D level was dichotomized, patients with levels <20 ng/mL had higher odds of nonspecific musculoskeletal pain (OR, 2.33; 95% CI, 1.23–4.17) compared with patients with levels ≥20 ng/mL. Conclusions: In adult patients, serum 25(OH)D level on admission to ARU was inversely associated with nonspecific musculoskeletal pain. These data support the need for randomized, controlled trials to test the role of vitamin D supplementation to improve nonspecific musculoskeletal pain in ARU patients.