Prevalence and Determinants of Vitamin D Deficiency in 1825 Cape Town Primary Schoolchildren: A Cross-Sectional Study

Vitamin D deficiency (25-hydroxyvitamin D[25(OH)D] <50 nmol/L) is common among adults in Cape Town, South Africa, but studies investigating vitamin D status of children in this setting are lacking. We conducted a cross-sectional study to determine the prevalence and determinants of vitamin D deficiency in 1825 Cape Town schoolchildren aged 6–11 years. Prevalence of vitamin D deficiency was 7.6% (95% Confidence Interval [CI] 6.5% to 8.9%). Determinants of vitamin D deficiency included month of sampling (adjusted odds ratio [aOR] for July–September vs. January–March 10.69, 95% CI 5.02 to 22.77; aOR for October–December vs. January–March 6.73, 95% CI 2.82 to 16.08), older age (aOR 1.25 per increasing year, 95% CI: 1.01–1.53) and higher body mass index (BMI; aOR 1.24 per unit increase in BMI-for-age Z-score, 95% CI: 1.03–1.49). In a subset of 370 participants in whom parathyroid hormone (PTH) concentrations were measured; these were inversely related to serum 25(OH)D concentrations (p < 0.001). However, no association between participants with hyperparathyroidism (PTH >6.9 pmol/L) and vitamin D deficiency was seen (p = 0.42). In conclusion, we report that season is the major determinant of vitamin D status among Cape Town primary schoolchildren, with prevalence of vitamin D deficiency ranging from 1.4% in January–March to 22.8% in July–September.     

Vitamin D Deficiency in Pregnant Ukrainian Women: Effects of Alcohol Consumption on Vitamin D Status

Objective: Heavy alcohol consumption can alter vitamin D status; however, the relationships between alcohol consumption and vitamin D concentrations in pregnant women have not been well studied. The aim of this study was to investigate the vitamin D status in a population of alcohol-exposed (N = 180) and low/unexposed control (N = 179) Ukrainian pregnant women.

Methods: Women who attended prenatal care facilities in 2 regions of Ukraine (Rivne and Khmelnytsky) for a routine prenatal visit were screened for the study. At the time of enrollment (20.4 ± 7.0 weeks of gestation), blood samples and alcohol consumption data (during a typical week around conception and the most recent 2 weeks) were collected. Vitamin D status was assessed by 25-hydroxyvitamin D [25(OH)D] concentrations.

Results: A high prevalence of suboptimal vitamin D status in pregnant Ukrainian women was observed. Overall, 50.1% and 33.4% of the women were classified as vitamin D deficient [25(OH)D < 20 ng/mL] or insufficient [25(OH)D ≥ 20 ng/mL and ≤30 ng/mL], respectively, based on 2011 Endocrine Society guidelines. Alcohol-exposed women had significantly lower 25(OH)D concentrations than low/unexposed women in Spring (p = 0.006) and Winter (p = 0.022). When vitamin D concentrations were grouped into sunny season (Summer + Fall) compared to not sunny season (Winter + Spring), there was a significant ethanol by season interaction (p = 0.0028), with alcohol-drinking women having lower circulating vitamin D compared to low/unexposed women in seasons of low sun availability.

Conclusions: These data suggest that when vitamin D concentrations are generally low (e.g., during seasons of low sun availability), alcohol consumption during pregnancy has a negative impact on vitamin D status.     

High Prevalence of Vitamin D Deficiency in Infertile Women Referring for Assisted Reproduction

A comprehensive analysis of the vitamin D status of infertile women is the first step in understanding hypovitaminosis impact on reproductive potential. We sought to determine vitamin D profiles of women attending an infertility center and to investigate non-dietary determinants of vitamin D status in this population. In this cross-sectional analysis, a cohort of 1072 women (mean age ± standard deviation 36.3 ± 4.4 years) attending an academic infertility center was used to examine serum 25-hydroxy-vitamin D (25(OH)D) levels in relation to demographic characteristics, seasons and general health risk factors. Both unadjusted and adjusted levels of serum 25(OH)D were examined. Median 25(OH)D concentration was below 30 ng/mL for 89% of the entire year. Over the whole year, 6.5% of patients had 25(OH)D levels ≤10 ng/mL, 40.1% ≤20 ng/mL, and 77.4% ≤30 ng/mL. Global solar radiation was weakly correlated with 25(OH)D levels. At multivariable analysis, 25(OH)D levels were inversely associated with BMI; conversely, 25(OH)D levels were positively associated with height and endometriosis history. Serum 25(OH)D levels are highly deficient in women seeking medical help for couple’s infertility. Levels are significantly associated with body composition, seasonal modifications and causes of infertility. Importantly, this deficiency status may last during pregnancy with more severe consequences.     

Distribution and Determinants of Vitamin D-Binding Protein,Total, “Non-Bioavailable”, Bioavailable,and Free 25-Hydroxyvitamin D Concentrations among Older Adults

Background: serum 25-hydroxyvitamin D (25(OH)D) (“total 25 OH(D)”) is the most commonly used indicator of vitamin D status. However, 25(OH)D is mostly bound to the vitamin D binding protein (VDBP) or albumin in blood, and it has been suggested that the remaining bioavailable or free 25(OH)D may be more relevant for vitamin D associated health outcomes. We aimed to explore distributions and determinants of VDBP, total, bioavailable, complementary “non-bioavailable”, and free 25(OH)D in a large cohort of older adults in Germany. Methods: total 25(OH)D, VDBP, and albumin concentrations were measured in blood samples of 5899 men and women aged 50–75 years and used to calculate bioavailable (and complementary “non-bioavailable”) and free 25(OH)D concentrations. Linear regression models were used to evaluate associations of potential determinants of the various vitamin D biomarkers. Results: mean concentrations of VDBP, total, non-bioavailable, bioavailable, and free 25(OH)D were 323.6 µg/mL, 49.8 nmol/L, 43.4 nmol/L, 2.5 ng/mL, and 5.7 pg/mL, respectively. Seasonal variations were observed for all markers, with peak values in spring for VDBP and in summer for total, non-bioavailable, bioavailable, and free 25(OH)D. Consistent inverse associations were seen with age and body mass index for all markers, but divergent associations were seen with C-reactive protein. Strong variations by VDBP genotypes were seen for bioavailable and free 25(OH)D, and, in opposite direction for non-bioavailable 25(OH)D. Conclusion: commonalities and differences in determinants of various markers of vitamin D status were observed, which may help to enable a better understanding of their potential role for various vitamin D related health outcomes.     

Smoking Exposure Is Associated with Serum Vitamin D Deficiency in Children: Evidence from the Japan Environment and Children’s Study

Tobacco smoke exposure is known to lower serum 25-hydroxyvitamin D (25(OH)D) concentrations. This study evaluated the association between passive smoking and vitamin D deficiency (VDD) in young children using data from the Japan Environment and Children’s Study (JECS), the largest birth cohort study in Japan. Information on parental smoking status was extracted from a survey of JECS for children aged 1.5 years and data for serum 25(OH)D concentrations were obtained from blood tests in the Sub-Cohort Study of JECS performed at age 2 years. Logistic regression and linear models were fitted to evaluate the association between these variables. Data were analyzed for 4593 children. After adjusting for covariates, smoke exposure was significantly associated with increased incidence of VDD (OR 1.35; 95% CI, 1.14–1.59) according to the logistic model. The linear model indicated that passive smoking negatively predicted de-seasonalized serum 25(OH)D concentrations (β −0.5; 95% CI −0.95 to −0.08) in children aged 2 years. The results suggest that smoke exposure is a risk factor for VDD in children. Given that VD plays a crucial role in bone metabolism and the immune system, our findings are significant for clinical and public health.     

Vitamin D Deficiency in India: Prevalence,Causalities and Interventions

Vitamin D deficiency prevails in epidemic proportions all over the Indian subcontinent, with a prevalence of 70%–100% in the general population. In India, widely consumed food items such as dairy products are rarely fortified with vitamin D. Indian socioreligious and cultural practices do not facilitate adequate sun exposure, thereby negating potential benefits of plentiful sunshine. Consequently, subclinical vitamin D deficiency is highly prevalent in both urban and rural settings, and across all socioeconomic and geographic strata. Vitamin D deficiency is likely to play an important role in the very high prevalence of rickets, osteoporosis, cardiovascular diseases, diabetes, cancer and infections such as tuberculosis in India. Fortification of staple foods with vitamin D is the most viable population based strategy to achieve vitamin D sufficiency. Unfortunately, even in advanced countries like USA and Canada, food fortification strategies with vitamin D have been only partially effective and have largely failed to attain vitamin D sufficiency. This article reviews the status of vitamin D nutrition in the Indian subcontinent and also the underlying causes for this epidemic. Implementation of population based educational and interventional strategies to combat this scourge require recognition of vitamin D deficiency as a public health problem by the governing bodies so that healthcare funds can be allocated appropriately.     

Associations between Maternal Selenium Status and Cord Serum Vitamin D Levels: A Birth Cohort Study in Wuhan,China

Serum selenium (Se) has been reported to be associated with serum 25-hydroxyvitamin D [25(OH)D], but epidemiological findings are limited in pregnant women. We aimed to assess the associations between maternal urinary Se concentrations and cord serum 25(OH)D levels. We measured urinary concentrations of Se in the first, second, and third trimesters and cord serum 25(OH)D of 1695 mother-infant pairs from a prospective cohort study in Wuhan, China. The results showed that each doubling of urinary Se concentrations in the first, second, third trimester, and whole pregnancy (average SG-adjusted concentrations across three trimesters) were associated with 8.76% (95% confidence interval (CI): 4.30%, 13.41%), 15.44% (95% CI: 9.18%, 22.06%), 11.84% (95% CI: 6.09%, 17.89%), and 21.14% (95% CI: 8.69%, 35.02%) increases in 25(OH)D levels. Newborns whose mothers with low (<10 μg/L) or medium (10.92–14.34 μg/L) tertiles of urinary Se concentrations in whole pregnancy were more likely to be vitamin D deficient (<20 ng/mL) compared with those with the highest tertile (>14.34 μg/L). Our study provides evidence that maternal Se levels were positively associated with cord serum vitamin D status.     

The potential role of vitamin D enhanced foods in improving vitamin D status

Low vitamin D intake and status have been reported worldwide and many studies have suggested that this low status may be involved in the development of several chronic diseases. There are a limited number of natural dietary sources of vitamin D leading to a real need for alternatives to improve dietary intake. Enhancement of foods with vitamin D is a possible mode for ensuring increased consumption and thus improved vitamin D status. The present review examines studies investigating effects of vitamin D enhanced foods in humans and the feasibility of the approach is discussed.     

Use of Vitamin D Supplements in Osteoarthritis: An Observational Study in a Tertiary Health Care Facility

Objective: The purpose of the study was to assess impact of vitamin D supplements on the disease progression and overall health of osteoarthritis (OA) patients.

Methodology: A cohort study was carried out for 8?months (August 2017–March 2018) in the Orthopedics Department of Kasturba Hospital, Manipal, India, a tertiary care hospital. One hundred and forty-two patients who were diagnosed with OA (grades 1–3) with low serum 25(OH)D levels (severely deficient, deficient, or insufficient) were selected for the study. These patients were categorized into two cohorts: a control cohort (CC) and a study cohort (SC). CC members were patients (n?=?71) who had not received vitamin D supplements, and SC members were patients (n?=?71) who had received vitamin D supplements. Severity grading of OA, pain score, and health assessment were performed using the Kellgren–Laurence grading score, visual analogue scale (VAS), and WOMAC, respectively, at baseline and after 3?months of follow-up.

Results: Subjects in the both CC and SC reported no statistically significant difference (similar in both group) in severity grade (p?=?0.303), pain score (p?=?0.099), parathyroid hormone (PTH) (p?=?0.083), and health status (p?=?0.76) at baseline. After 3?months of follow-up (post vitamin D supplementation), OA patients have shown statistically significant difference in severity grades, serum 25(OH)D status, PTH level (p?<?0.001), and overall health status (p?=?0.001) in the SC with respect to baseline. Likewise, percentage distribution of positive changes was significantly higher in severity grade, pain score, serum 25(OH)D level, overall health status (p?<?0.001), and PTH (p?=?0.040) of SC as compared to CC at follow-up.

Conclusion: Vitamin D supplements have significantly improved serum 25(OH)D levels, PTH, severity grade, and pain score of OA patients. Most importantly, vitamin D supplements have shown improvement in the overall health of OA patients, emphasizing the place of vitamin D supplements in the management of OA.

Clinical Trial Registry-India (CTRI) registration no: CTRI/2017/12/011031     

Vitamin D Status and Severity of Clostridium difficile Infections

Background: Clostridium difficile is the most common cause of nosocomial diarrhea, affecting up to 10% of hospitalized patients. Preliminary studies suggest an association between vitamin D status and C difficile infections (CDIs). Our goal was to investigate whether serum 25‐hydroxyvitamin D (25(OH)D) levels are associated with CDI severity. Methods: We prospectively enrolled patients diagnosed with CDI and divided them into 2 severity groups: group A (positive toxin A/B enzyme immunoassay only) and group B (positive toxin A/B enzyme immunoassay with abdominal computed tomography scan findings consistent with colitis). Serum 25(OH)D levels (25(OH)D₃, 25(OH)D₂, and total 25(OH)D) were measured on all patients after diagnosis of CDI. We performed multivariable logistic regression analyses to investigate the association between 25(OH)D levels and CDI severity, while adjusting for age, Deyo‐Charlson Comorbidity Index, recent hospitalization, and vitamin D supplementation. Results: One hundred patients were enrolled between July 2011 and February 2013. The mean (standard deviation) cohort age and Deyo‐Charlson Comorbidity Index were 62 (19) years and 4 (3), respectively; 54% of patients were male. Mean serum total 25(OH)D level was 22 (10) ng/mL. Mean 25(OH)D₃ level was significantly higher in group A (n = 71) than in group B (n = 29): 21 (1) vs 15 (2) ng/mL, respectively (P = .005). There was no observed difference in mean 25(OH)D₂ levels and total 25(OH)D levels between the 2 groups. Multivariable logistic regression analysis demonstrated an association between 25(OH)D₃ levels and CDI severity (adjusted odds ratio, 0.92; 95% confidence interval, 0.87–0.98). Conclusions: We found a significant inverse association between 25(OH)D₃ levels and CDI severity. Further studies are needed to determine whether vitamin D supplementation can improve outcomes in patients with CDI.     

Vitamin D Status and Gestational Diabetes in Russian Pregnant Women in the Period between 2012 and 2021: A Nested Case–Control Study

Several meta-analyses found an association between low maternal serum 25-hydroxyvitamin D (25(OH)D) level and gestational diabetes mellitus (GDM). However, some of them reported significant heterogeneity. We examined the association of serum 25(OH)D concentration measured in the first and in the second halves of pregnancy with the development of GDM in Russian women surveyed in the periods of 2012–2014 and 2018–2021. We conducted a case–control study (including 318 pregnant women) nested on two previous studies. In 2012–2014, a total of 214 women (83 GDM and 131 controls) were enrolled before 15 weeks of gestation and maternal serum 25(OH)D concentrations were measured twice: at 8th–14th week of gestation and simultaneously with two-hour 75 g oral glucose tolerance test (OGTT) at 24th–32nd week of gestation. In the period of 2018–2021, 104 women (56 GDM and 48 controls) were included after OGTT and 25(OH)D concentrations were measured at 24th–32nd week of gestation. Median 25(OH)D levels were 20.0 [15.1–25.7] vs. 20.5 [14.5–27.5] ng/mL (p = 0.565) in GDM and control group in the first half of pregnancy and 25.3 [19.8–33.0] vs. 26.7 [20.8–36.8] ng/mL (p = 0.471) in the second half of pregnancy, respectively. The prevalence rates for vitamin D deficiency (25(OH)D levels < 20 ng/mL) were 49.4% and 45.8% (p = 0.608) in the first half of pregnancy and 26.2% vs. 22.1% (p = 0.516) in the second half of pregnancy in women who developed GDM and in women without GDM, respectively. The frequency of vitamin D supplements intake during pregnancy increased in 2018–2021 compared to 2012–2014 (p = 0.001). However, the third trimester 25(OH)D levels and prevalence of vitamin D deficiency (25.5 vs. 23.1, p = 0.744) did not differ in women examined in the periods of 2012–2014 and 2018–2021. To conclude, there was no association between gestational diabetes risk and maternal 25(OH)D measured both in the first and in the second halves of pregnancy. The increased prevalence of vitamin D supplements intake during pregnancy by 2018–2021 did not lead to higher levels of 25(OH)D.     

Vitamin D Deficiency and Gestational Diabetes Mellitus in Relation to Body Mass Index

A relationship between vitamin D deficiency (VDD) and gestational diabetes mellitus (GDM) has been described. Considering that GDM prevalence depends on body mass index (BMI), our main objective was to determine if VDD is associated with GDM, independent of BMI. A cross-sectional study with 886 pregnant women was conducted in Elda (Spain) from September 2019 to June 2020. To assess the association, Poisson regression models with robust variance were used to estimate the prevalence ratio (PR). The observed GDM prevalence was 10.5%, while the VDD prevalence was 55.5%. In the crude model, both VDD and obesity were associated with GDM, but in the adjusted model, only VDD was statistically significant (PR = 1.635, p = 0.038). A secondary event analysis did not detect differences in VDD, but BMI yielded a higher frequency of births by cesarean section and newborns with a >90 percentile weight in the obesity group. In conclusion, VDD is associated with GDM, independent of BMI. Future longitudinal studies could provide information on causality.     

Factors Affecting 25-Hydroxyvitamin D Concentration in Response to Vitamin D Supplementation

Sun exposure is the main source of vitamin D. Due to many lifestyle risk factors vitamin D deficiency/insufficiency is becoming a worldwide health problem. Low 25(OH)D concentration is associated with adverse musculoskeletal and non-musculoskeletal health outcomes. Vitamin D supplementation is currently the best approach to treat deficiency and to maintain adequacy. In response to a given dose of vitamin D, the effect on 25(OH)D concentration differs between individuals, and it is imperative that factors affecting this response be identified. For this review, a comprehensive literature search was conducted to identify those factors and to explore their significance in relation to circulating 25(OH)D response to vitamin D supplementation. The effect of several demographic/biological factors such as baseline 25(OH)D, aging, body mass index(BMI)/body fat percentage, ethnicity, calcium intake, genetics, oestrogen use, dietary fat content and composition, and some diseases and medications has been addressed. Furthermore, strategies employed by researchers or health care providers (type, dose and duration of vitamin D supplementation) and environment (season) are other contributing factors. With the exception of baseline 25(OH)D, BMI/body fat percentage, dose and type of vitamin D, the relative importance of other factors and the mechanisms by which these factors may affect the response remains to be determined.     

Vitamin D Status Is Associated with Modifiable Lifestyle Factors in Pre-Adolescent Children Living in Urban Kuala Lumpur,Malaysia

Studies on vitamin D status and its determinants in growing children in countries with ample sunshine such as Malaysia have been limited. The aim of our study was to determine factors associated with serum 25(OH)D concentrations such as lifestyle, dietary intake, anthropometry, and body composition in 243 pre-adolescent Malaysian children from low-income families living in Kuala Lumpur. This cross-sectional study measured bone density and body composition using dual-energy X-ray absorptiometry (DXA), while serum 25(OH)D was measured using LC–MS/MS. Time spent outdoors, body surface area exposed to sunlight, dietary intake, and physical activity level were assessed using questionnaires. Multiple linear regression and stepwise analysis were performed to identify significant predictors for serum 25(OH)D. About 69.4% had 25(OH)D < 50 nmol/L, and 18.9% were vitamin-D-deficient with 25(OH)D < 30 nmol/L. Girls had a nine-fold higher prevalence of vitamin D deficiency than boys. Body surface area exposed to sunlight, Sun Index, and fat mass were significant predictors of 25(OH)D concentrations in this population. Modifiable lifestyle factors such as sun exposure and reducing obesity are important public health guidance to ensure optimal vitamin D status in these children.     

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.     

Vitamin D Status in Spanish Elite Team Sport Players

Low vitamin D is usual; however, data are limited for elite team players. The aim was to investigate the vitamin D levels in Football Club Barcelona (FCB) first division players of six sport modalities. Ninety-five elite male players (27.3 ± 4.6 y) belonging to FCB provided data for vitamin D throughout a season. In this study, 25(OH)D was measured in serum by chemiluminescent immunoassay. Outdoor/indoor training and supplementation were also considered. Total mean 25(OH)D concentrations were 91.9 ± 23.1 nmol/L in all players, with higher mean levels among supplemented players (94.7 ± 24.3 nmol/L). Around 25% of the team players were below optimal levels (<75 nmol/L), but none were below 50 nmol/L. Caucasian, supplemented football and handball players had the highest mean vitamin D concentrations over the whole year, whereas basketball players (indoor training) had the lowest ones. The highest rate of vitamin D insufficiency was found in spring (40%). A positive significant effect was observed for the interaction between indoor/outdoor training and supplementation with 25(OH)D concentrations (p < 0.05). Those team players training outdoors with supplementation had higher total vitamin D concentrations than those with indoors training and/or supplementation. A positive interaction of outdoor training with supplementation exists to determine 25(OH)D concentrations in team players.     

Parathyroid Hormone in Pregnancy: Vitamin D and Other Determinants

We aimed to assess the parathyroid hormone (PTH) concentration in pregnant women at the beginning of pregnancy (1st trimester) and within days before delivery (3rd trimester) and evaluate its determinants. From September 2014 through December 2015 in a cross-sectional study, 204 women in the 1st trimester of pregnancy and 203 women in the 3rd trimester of pregnancy were recruited. Blood samples were collected to measure PTH and circulating 25-hydroxy-vitamin D (25(OH)D) concentrations. Lifestyle and demographic data were collected using a questionnaire. Serum 25(OH)D and PTH were inversely correlated in both early and late pregnancy. Our analyses suggest that in the 3rd trimester of pregnancy, a 25(OH)D level of 18.9 ng/mL (47.3 nmol/L) could serve as an inflection point for the maximal suppression of PTH. Statistically significant determinants of PTH concentrations in multiple regression were 25(OH)D concentrations, season, multiparity and education of the partner (all p < 0.05) in early pregnancy. In late pregnancy, 25(OH)D concentrations and country of origin were statistically significant determinants of PTH concentrations (all p < 0.05). These factors and their effect on PTH appear to be vastly determined by 25(OH)D; however, they might also affect PTH through other mechanisms besides 25(OH)D.     

A High Prevalence of Vitamin D Deficiency Observed in an Irish South East Asian Population: A Cross-Sectional Observation Study

At northern latitudes, non-ethnic population groups can be at an increased risk of vitamin D deficiency (defined as a 25-hydroxyvitamin D [25(OH)D] status ≤30 nmol/L). The vitamin D status of ethnic minority groups has been examined both in UK and European populations, but not in the Irish context. The aim of this study is to assess the vitamin D status from a selection of the Dublin population of South East Asian descent. A search was conducted, using the laboratory information system of St James’s Hospital, Dublin, for vitamin D requests by General practitioners. From 2013 to 2016, 186 participants were identified and 25(OH)D analysis was quantified using liquid chromatography-tandem mass spectrometry (LC-MS-MS). Overall, the median age was 32 years, 51% were male, and the 25(OH)D concentration ranged from 10 to 154 nmol/L. In total, 66.7% of the total sample were vitamin D deficient and 6.7% had a 25(OH)D status greater than 50 nmol/L (the 25(OH)D concentration defined by the EU as ‘sufficient’). Females had a significantly higher 25(OH)D concentration than males (25.0 vs. 18.0 nmol/L; p = 0.001) but both groups had a significant proportion with deficient status (56% and 76.8%, respectively). Seasonal variation of 25(OH)D was not evident while high rates of deficiency were also observed in those aged <18 years and >50 years. Given the importance of vitamin D for health, this sub-population could be at a significantly increased risk of rickets, impaired bone metabolism, and osteoporosis. In addition, vitamin D deficiency has been associated with several non-bone related conditions, including cardiovascular disease and diabetes. Currently, there is no unique vitamin D intake or vitamin D status maintenance guidelines recommended for adults of non-Irish descent; this needs to be considered by the relevant public health bodies in Ireland.     

The Role of Vitamin D in Stroke Prevention and the Effects of Its Supplementation for Post-Stroke Rehabilitation: A Narrative Review

Hypovitaminosis D is a serious public health problem, representing an independent factor in mortality among the general population. Vitamin D deficiency may affect up to one billion people worldwide. Recently, the potential association between vitamin D levels and stroke has gained increasing attention. Many studies suggest that maintaining normal serum vitamin D levels is associated with improvement of the cardiovascular system and a reduction in stroke risk. As a neurosteroid, vitamin D influences brain development and function and immunomodulation and affects brain neuroplasticity. It supports many processes that maintain homeostasis in the body. As stroke is the second most common cause of death worldwide, more studies are needed to confirm the positive effects of vitamin D supplementation, its dosage at different stages of the disease, method of determination, and effect on stroke onset and recovery. Many studies on stroke survivors indicate that serum vitamin D levels only offer insignificant benefits and are not beneficial to recovery. This review article aims to highlight recent publications that have examined the potential of vitamin D supplementation to improve rehabilitation outcomes in stroke survivors. Particular attention has been paid to stroke prevention.