Vitamin D status and its association with adiposity and oxidative stress in schoolchildren

ObjectiveThe aim of this study was to evaluate serum 25-hydroxyvitamin D [25(OH)D] level and its association with adiposity, inflammation, and oxidative stress in schoolchildren.MethodsA total of 1488 schoolchildren ages 7 to 11 y were recruited in Harbin, China (latitude: 44°04′N–46°40′N) in May. Serum 25(OH)D, which is an indicator of vitamin D status, was determined. Anthropometric data were collected following general physical examinations. Serum lipids, glucose metabolism indices, inflammatory molecules, and oxidative stress markers were determined. Dietary intake and physical activity also were assessed.ResultsThe median serum 25(OH)D concentration was 18.4 ng/mL. Of the 1488 schoolchildren included, 839 (56.4%) had vitamin D deficiency [25(OH)D < 20 ng/mL]. Children in the vitamin D deficiency group had significantly higher body weight (34.1 ± 3.8 versus 31.5 ± 3.3 kg; P < 0.001), body mass index (18.4 ± 2.2 versus 16.8 ± 1.7 kg/m²; P < 0.001), waist circumference (60.1 ± 8.5 versus 57.2 ± 7.7 cm; P < 0.001), percentage of body fat (20.2% ± 2.6% versus 19.1% ± 2.4%; P < 0.001), and significantly lower concentrations of serum superoxide dismutase (95.38 ± 12.22 versus 127.62 ± 15.98 U/mL; P < 0.001) compared with those in the vitamin D sufficiency group. After adjusting for sex, age, body mass index, and percentage of body fat, a positive association between serum 25(OH)D and superoxide dismutase was found (β = 0.230; P < 0.001).ConclusionsVitamin D deficiency is common in Harbin schoolchildren. Serum 25(OH)D is closely associated with adiposity and superoxide dismutase in schoolchildren, suggesting that vitamin D deficiency potentially increases the risk for diseases caused by higher adiposity and oxidative stress.     

A Randomized Clinical Trial of Vitamin D Supplementation in Healthy Adolescents

PurposeThe most safe and effective dose of vitamin D supplementation for healthy adolescents is currently unknown. The aim of this study was to compare the efficacy of 200 IU versus 1,000 IU of daily vitamin D₃ for supplementation in healthy adolescents with baseline vitamin D sufficiency.MethodsWe conducted a double-blind, randomized clinical trial. Fifty-six subjects, ages 11–19 years, with baseline vitamin D sufficiency received 1,000 IU or 200 IU of daily vitamin D₃ for 11 weeks. Compliance was assessed using MEMS6 Trackcaps and pill counts.ResultsFifty-three subjects completed the clinical trial. Subjects in the two treatment arms were similar in terms of age, race, gender, body mass index, and dietary calcium and vitamin D intake. Serum 25(OH)D level in the 200 IU treatment arm was 28.1 ± 6.2 ng/mL at baseline (mean ± SD) and 28.9 ± 7.0 ng/mL at follow-up. In the 1,000 IU treatment arm, 25(OH)D levels were 29.0 ± 7.3 and 30.1 ± 6.6 at baseline and follow-up, respectively. Mean change in 25(OH)D level did not differ significantly between treatment arms (p = .87), nor did mean change in parathyroid hormone, calcium, phosphate, bone turnover markers, fasting glucose, or fasting insulin.ConclusionsIn healthy adolescents with baseline vitamin D sufficiency, supplementation with vitamin D₃ doses of 200 and 1,000 IU for 11 weeks did not increase serum 25(OH)D levels, with no significant difference observed between treatment arms.     

Increased vitamin D-binding protein and decreased free 25(OH)D in obese women of reproductive age

Purpose

Obese subjects have lower circulating 25-hydroxyvitamin D (25(OH)D) than normal-weight subjects. Knowledge is scarce regarding differences in vitamin D-binding protein (DBP), free 25(OH)D, and intake of vitamin D between normal-weight and obese subjects. The purpose of this study was to examine intake and vitamin D status in obese compared with normal-weight women.

Methods

Between September 2009 and October 2011, 43 obese and 43 normal-weight women, 22–45 years of age, mean BMI of 39.1 ± 4.6 and 21.6 ± 1.8 kg/m², respectively, were recruited in the western Sweden region (latitude 57°N). Blood samples, data regarding diet, and sun exposure were collected.

Results

DBP concentrations were 320 ± 121 and 266 ± 104 μg/mL (P = 0.02) in obese and normal-weight women, respectively. Calculated free 25(OH)D was 13.3 ± 5.5 (obese) and 23.7 ± 10.7 (normal-weight) (P < 0.001). The obese women had a 20.1 nmol/L lower mean 25(HO)D concentration compared to normal-weight women (P < 0.001). 56 % of obese women and 12 % of normal-weight women had 25(OH)D concentrations ≤50 nmol/L. There was no statistically significant difference in total vitamin D intake between the groups. 39 % of the women had a total vitamin D intake <7.5 μg/day, the current national recommendation for vitamin D in Sweden.

Conclusions

Obese women had higher DBP concentrations compared with normal-weight women and lower free 25(OH)D. The obese women were more likely to have 25(OH)D concentrations that could be considered suboptimal. Vitamin D intake was generally low in normal-weight and obese women of childbearing age.     

Effects of sunlight and diet on vitamin D status of pulmonary tuberculosis patients in Tbilisi, Georgia

ObjectiveVitamin D deficiency is common in tuberculosis (TB) and this may modulate immune responses. This study investigated vitamin D status in patients with TB and examined the sources of vitamin D in Tbilisi, Georgia.MethodsWe measured plasma 25-hydroxyvitamin D (25[OH]D) and dietary vitamin D intake in patients with pulmonary TB (n = 85) in Tbilisi, Georgia. To determine the impact of season on vitamin D status, we tested the in vitro conversion of 7-dehydrocholesterol (7-DHC) to previtamin D₃ after sunlight exposure.ResultsIn subjects with TB, mean plasma 25(OH)D concentrations were 14.4 ± 7.0 ng/mL, and vitamin D insufficiency (25[OH]D <30 ng/mL) occurred in 97% of subjects. The dietary sources of vitamin D were mainly fish, eggs, and butter. The daily intake was well below recommended daily intakes in subjects with TB (172 ± 196 IU). The conversion of 7-DHC to previtamin D₃ was undetectable from October to March and highest in June and July from 11:00 to 14:00 h.ConclusionAn insufficient vitamin D dietary intake and a limited production of vitamin D from sunlight for most of the year may explain the high prevalence of vitamin D insufficiency in patients with TB in Tbilisi.     

Multinutrient-Fortified Juices Improve Vitamin D and Vitamin E Status in Children: A Randomized Controlled Trial

BackgroundProvision of fortified juices may provide a convenient method to maintain and increase blood fat-soluble vitamins.ObjectiveTo determine whether children consuming orange juice fortified with calcium and combinations of vitamins D, E, and A could increase serum 25-hydroxyvitamin D [25(OH)D], α-tocopherol, and retinol levels.DesignA 12-week randomized, double-blind, controlled trial.Participants/settingOne hundred eighty participants (aged 8.04±1.42 years) were recruited at Tufts (n=70) and Boston University (n=110) during 2005-2006. Of those recruited, 176 children were randomized into three groups: CaD (700 mg calcium+200 IU vitamin D), CaDEA (700 mg calcium+200 IU vitamin D+12 IU vitamin E+2,000 IU vitamin A as beta carotene), or Ca (700 mg calcium). Children consumed two 240-mL glasses of CaD, CaDEA, or Ca fortified orange juice daily for 12 weeks.Main outcome measuresSerum 25(OH)D, α-tocopherol, and retinol concentrations.Statistical analysesChanges in 25(OH)D, α-tocopherol, retinol, and parathyroid hormone concentrations were examined. Covariates included sex, age, race/ethnicity, body mass index, and baseline 25(OH)D, α-tocopherol, retinol, or parathyroid hormone levels. Multivariate models and repeated measures analysis of variance tested for group differences with pre–post measures (n=141).ResultsBaseline 25(OH)D was 68.4±27.7 nmol/L (27.4±11.10 ng/mL) ), with 21.7% of participants having inadequate 25(OH)D (<50 nmol/L [20.03 ng/mL]). The CaD group's 25(OH)D increase was greater than that of the Ca group (12.7 nmol/L [5.09 ng/mL], 95% CI 1.3 to 24.1; P=0.029). The CaDEA group's increase in α-tocopherol concentration was greater than that in the Ca or CaD groups (3.79 μmol/L [0.16 μg/mL], 95% CI 2.5 to 5.1 and 3.09 μmol/L [0.13 μg/mL], 95% CI −1.8 to 4.3), respectively (P<0.0001). Retinol levels did not change, and body weight remained as expected for growth.ConclusionsDaily consumption of orange juice providing 200 IU vitamin D and 12 IU vitamin E increased 25(OH)D and α-tocopherol concentrations in young children within 12 weeks.     

Evaluation of the deficiency status of 25-hydroxyvitamin D and associated factors in Southwest China: A hospital-based retrospective cross-sectional analysis of a low-latitude,high-altitude,multiracial region

Vitamin D deficiency is widespread in different populations and regions worldwide and has become a global health issue. The vitamin D status of the population in the Yunnan Province of Southwest China has not been evaluated to date. Therefore, in this study, we evaluated the vitamin D status according to the serum concentrations of 25-hydroxyvitamin D (25(OH)D) in individuals of Yunnan Province, a low-latitude, high-altitude and multiracial region in China. The data on 25(OH)D concentrations from October 2012 to December 2017 were retrospectively collected and assessed using the laboratory information system from 52 950 hospital-based participants (age, 1 day–96 years; females, 73.74%). The serum concentration of 25(OH)D was evaluated using a chemiluminescent immunoassay. The analysis was stratified by sex, age, sampling season, testing year, minority, residential district, latitude, altitude and meteorological factors. Vitamin D status was classified as follows: severe deficiency: <10 ng/mL; deficiency: <20 ng/mL; insufficiency: <30 ng/mL; and sufficiency: ≥30 ng/mL. The results showed that vitamin D deficiency is highly prevalent in Yunnan Province in a hospital-based cohort, with a deficiency and severe deficiency rate of 65.1% and a sufficiency rate of 5.30%. Significantly lower vitamin D levels and sufficiency rates were observed in females than in males (20.13 ± 7.22 ng/mL vs. 17.56 ± 6.66 ng/mL and 8.20% vs. 4.20%; p < 0.01, respectively); in spring and winter (16.93 ± 6.24 ng/mL; 2.97% and 16.38 ± 6.43 ng/mL; 3.06%, respectively) than in summer and autumn (20.23 ± 7.14 ng/mL; 8.02% and 19.10 ± 6.97 ng/mL; 6.61% [p < 0.01], respectively); and in older individuals (0–6 years: 28.29 ± 13.13 ng/mL vs. >60 years: 14.88 ± 8.39 ng/mL; p < 0.01). Relatively higher vitamin D levels were observed in individuals of Yi, Zhuang, Hani, Dai, Miao and Lisu minorities and lower levels in individuals of Hui and Zang minorities compared with those of the Han nationality (p < 0.01). The mean sunlight duration, mean air temperature, maximum ultraviolet value and latitude were significantly correlated with vitamin D levels (r = −0.53, 0.60, 0.31, −0.68, respectively; p < 0.05). These results suggest that vitamin D status is influenced by sex, age, minority, latitude and some meteorological factors in areas with high and low altitudes. Hence, new public health policies, such as advice on sunshine exposure, food fortification and nutrition education, as well as the implementation of vitamin D supplementation programmes must be considered to alleviate vitamin D deficiency in Yunnan province, Southwest China.     

The effect of body mass index on adequacy of serum 25-hydroxyvitamin D levels in US adults: the National Health and Nutrition Examination Survey 2001 to 2006

PurposeTo investigate the relationship between body mass index (BMI) and vitamin D adequacy among US adults.MethodsWe used data for US adults aged 18 years or older (n = 12,927) who participated in the 2001 to 2006 United States National Health and Nutrition Examination Survey. Log-binomial regression was used to estimate the strength of association between BMI categories and the prevalence of serum 25-hydroxyvitamin D [25(OH)D] greater than or equal to 20 ng/mL before and after controlling for selected characteristics. An interaction term between race or ethnicity and BMI categories was tested.ResultsAmong US adults, 67.2% had serum 25(OH)D greater than or equal to 20 ng/mL, a cut point suggested by the Office of Dietary Supplements for adequate bone and general health. Overweight and obese adults were 8% (95% confidence interval, 0.89–0.95) and 26% (95% confidence interval, 0.71–0.78), respectively, less likely to have serum 25(OH)D greater than or equal to 20 ng/mL than their normal weight counterparts after controlling for age, gender, race/ethnicity, nativity and marital status, as well as education and income. No heterogeneity of the association between BMI categories and the prevalence of 25(OH)D greater than or equal to 20 ng/mL was observed by race or ethnicity.ConclusionsThe low prevalence of 25(OH)D greater than equal to 20 ng/mL among overweight and obese adults in the US population underscores the need to comparatively assess vitamin D intakes across different BMIs.     

A high-fat diet in the presence of vitamin D deficiency status is associated with a negative influence on calcaneal quantitative ultrasound parameters in young adults: a cross-sectional study

Vitamin D deficiency and a high-fat diet are considered health problems worldwide. The aims of this study were to examine the prevalence of vitamin D deficiency/insufficiency in young adults, factors related to the vitamin D status, and the influence of vitamin D deficiency and/or a high-fat diet on bone parameters. Here, we investigated the hypothesis that a high-fat diet in the presence of a vitamin D-deficient status would have a more negative influence on bone parameters than a normal-fat diet with such a status. In the present study, we targeted young Japanese adults aged 21-23 (n = 175). We conducted a diet survey based on 3-day food records, biochemical examination of serum, and quantitative ultrasound measurements at the calcaneus. As a result, the rates of vitamin D deficiency {serum 25-hydroxyvitamin D₃ [25(OH)D] concentration less than 20 ng/mL} and insufficiency [serum 25(OH)D concentration less than 30 ng/mL but not less than 20 ng/mL] were 60.6 and 30.9%, respectively. A positive correlation was observed between the serum 25(OH)D level and serum bone-specific alkaline phosphatase level, which is a serum marker of bone formation (r = 0.253, P< .01) or the speed of sound (SOS) as an index of bone density (r = 0.259, P< .01). A negative correlation was observed between the ratio of fat intake to total energy intake (%E) and serum 25(OH)D levels (r = −0.206, P< .01). Furthermore, we revealed that a high-fat diet in the presence of a vitamin D deficient status reduced the SOS parameter compared with a normal-fat diet with a vitamin D-deficient status (P< .05).     

Vitamin D Deficiency Increases the Risk for Moderate to Severe Disease Activity in Crohn's Disease Patients in South Africa,Measured by the Harvey Bradshaw Index

Objective: Vitamin D has immunoregulatory properties and appears to influence disease outcomes in patients with Crohn's disease (CD). The primary aim of this study was to evaluate the association between vitamin D status and CD activity in South Africa.

Methods: In a cross-sectional study performed between September 2011 and January 2013, serum 25-hydroxyvitamin D (25(OH)D) was measured in 186 consecutive patients with CD seen at 2 inflammatory bowel disease (IBD) centers and 199 healthy controls in the Western Cape, South Africa. Lifestyle and clinical variables were identified using an investigator-administered questionnaire, as well as clinical examination and patient case notes. Vitamin D status was evaluated in 2 ways: ≤20 ng/mL vs ≥21 ng/mL and ≤29 ng/mL vs ≥30 ng/mL. Disease activity was measured by the Harvey Bradshaw Index (HBI). Various 25(OH)D threshold concentrations for predicting a higher HBI score were also investigated.

Results: On multiple log-binomial regression analysis, higher HBI scores and not having taken vitamin D supplementation in the 6 months prior to enrollment were identified as risk factors for vitamin D deficiency in patients with CD, defined either as ≤20 ng/mL or as ≤29 ng/mL (p < 0.03). Compared to patients with HBI < 5, those with HBI ≥ 8 were 2.5 times more likely to have 25(OH)D concentrations ≤21 ng/mL (prevalence risk [PR] = 2.5; 95% confidence interval [CI], 1.21–6.30). The risk was similar, though not as high, when defined as ≤29 ng/mL (PR = 2.0; 95% CI, 1.13–3.51). When vitamin D deficiency was defined as <20, <30, <40, and <50 ng/mL, the sensitivity and specificity obtained were 44.9% and 78.8%; 75.5% and 62.4%; 86.7% and 44.7%; and 92.9% and 23.5%, respectively (area under the curve = 0.71; p < 0.0001).

Conclusion: Low serum 25(OH)D was associated with increased CD activity in a South African cohort.     

Higher concentrations of vitamin D in Canadian children with juvenile idiopathic arthritis compared to healthy controls are associated with more frequent use of vitamin D supplements and season of birth

A number of studies have demonstrated that patients with autoimmune disease have lower levels of vitamin D prompting speculation that vitamin D might suppress inflammation and immune responses in children with juvenile idiopathic arthritis (JIA).  The objective of this study was to compare vitamin D levels in children with JIA at disease onset with healthy children. We hypothesized that children and adolescents with JIA have lower vitamin D levels than healthy children and adolescents. Data from a Canadian cohort of children with new-onset JIA (n= 164, data collection 2007-2012) were compared to Canadian Health Measures Survey (CHMS) data (n=4027, data collection 2007-2011). We compared 25-hydroxy vitamin D (25(OH)D) concentrations with measures of inflammation, vitamin D supplement use, milk intake, and season of birth. Mean 25(OH)D level was significantly higher in patients with JIA (79 ± 3.1 nmol/L) than in healthy controls (68 ± 1.8 nmol/L P <.05). Patients with JIA more often used vitamin D containing supplements (50% vs. 7%; P <.05). The prevalence of 25(OH)D deficiency (<30 nmol/L) was 6% for both groups. Children with JIA with 25(OH)D deficiency or insufficiency (<50 nmol/L) had higher C-reactive protein levels. Children with JIA were more often born in the fall and winter compared to healthy children. In contrast to earlier studies, we found vitamin D levels in Canadian children with JIA were higher compared to healthy children and associated with more frequent use of vitamin D supplements. Among children with JIA, low vitamin D levels were associated with indicators of greater inflammation.     

Breakfast Skipping Is Associated with Vitamin D Deficiency among Young Adults entering Initial Military Training

BackgroundVitamin D deficiency (VDD), defined as serum 25-hydroxyvitamin D (25[OH]D) levels < 20 ng/mL [to convert 25[OH]D ng/mL to nmol/L, multiply by 2.5]) is prevalent in young adults and has been associated with adverse health outcomes, including stress fracture during periods of increased physical activity such as military training. Foods commonly consumed at breakfast provide an important source of vitamin D, yet breakfast skipping is common among young adults. However, whether breakfast skipping is associated with VDD in young adults is unclear.ObjectivesThis study aimed to determine whether breakfast skipping is associated with odds of VDD among recruits entering initial military training (IMT), and with changes in serum 25(OH)D during IMT. In addition, whether diet quality and vitamin D intake mediated these associations was determined.DesignSecondary analysis of individual participant data collected during five IMT studies. Breakfast skipping (≥ 3 times/week) was self-reported. Dietary intake was determined using food frequency questionnaires, and vitamin D status was assessed using circulating 25(OH)D concentrations pre- and post-IMT.Participants and settingParticipants were healthy US Army, US Air Force, and US Marine recruits (N = 1,569, 55% male, mean ± standard deviation age 21 ± 4 years) entering military service between 2010 and 2015 at Fort Jackson, SC; Fort Sill, OK; Lakeland Air Force Base, TX; or the Marine Corps Recruit Depot, Parris Island, SC.Main outcome measuresPrimary outcomes were VDD pre-IMT and change in 25(OH)D from pre- to post-IMT.Statistical analysis performedAssociations were determined using multivariate-adjusted logistic and linear regression and mediation models.ResultsForty-six percent of military recruits were classified as breakfast skippers pre-IMT, and 30% were VDD. Breakfast skipping was associated with a higher odds of pre-IMT VDD (odds ratio 1.5, 95% CI 1.1 to 1.9), and lower vitamin D intake and diet quality were partial mediators of the association. Serum 25(OH)D concentrations improved (P = 0.01) among habitual breakfast skippers versus nonskippers during IMT; however, regression to the mean could not be ruled out. Neither change in diet quality nor vitamin D intake were associated with change in 25(OH)D concentrations during IMT.ConclusionsBreakfast skipping is prevalent among incoming military recruits and is associated with VDD. This relationship may be mediated by lower diet quality and vitamin D intake.     

National report on the association of serum vitamin D with cardiometabolic risk factors in the pediatric population of the Middle East and North Africa (MENA): The CASPIAN-III Study

ObjectivesAs the first, to our knowledge, nationwide study in the Middle East and North Africa (MENA), this study aimed to investigate the association of serum 25 hydroxy vitamin D [25(OH)D] levels with cardiometabolic risk factors in a nationally representative sample of the pediatric population in Iran. The second objective was to provide the prevalence of hypovitaminosis D and the percentiles of serum 25(OH)D in the study population.MethodsThis national population-based study was conducted among 1100 Iranian students living in 27 provinces in Iran. The association of 25(OH)D with each cardiometabolic risk factor was determined after adjustment for age, gender, body mass index, and waist circumference.ResultsParticipants consisted of 1095 students (52% boys) with a mean age of 14.74 ± 2.61 y. The median 25(OH)D level corresponded to a vitamin D insufficiency level: 12.70 ng/mL in boys and 13.20 ng/mL in girls. Overall, 40% of participants were vitamin D deficient, and 39% had vitamin D insufficiency. There were no significant differences in these findings between boys and girls. Adjusted regression analysis revealed a significant weak inverse association of 25(OH)D with systolic blood pressure, diastolic blood pressure, total cholesterol, and low-density lipoprotein cholesterol. This association was significantly positive with high-density lipoprotein cholesterol, but not with fasting plasma glucose and metabolic syndrome.ConclusionWe found a considerably high prevalence of hypovitaminosis D in the pediatric population of a sunny region. Our findings also revealed an association of hypovitaminosis D with many cardiometabolic risk factors from childhood; these associations were independent of obesity indexes. It is of special concern that the highly prevalent disorders of low 25(OH)D and low high-density lipoprotein cholesterol in children and adolescents of the MENA region had significant association. The clinical importance of our findings needs to be confirmed in longitudinal studies.     

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.     

Optimal Serum 25(OH)D Level and Vitamin D Intake in Young Korean Women

Vitamin D status is essential for preventing bone disease. Young Korean women have the highest vitamin D deficiency prevalence compared with other demographic groups. This study aimed to establish the optimal vitamin D intake level for maintaining an adequate serum 25-hydroxyvitamin D (25[OH]D) level by season in young Korean women (mean age: 23.1 years). Each participant (wintertime, n = 101; summertime, n = 117) completed a lifestyle survey, dietary record, bone mineral density, and biochemical tests. Seasonal factors impacting 25(OH)D were identified, vitamin D intake for sufficient 25(OH)D levels was calculated, and the relationship between 25(OH)D and intact parathyroid hormone (iPTH) was analyzed. During summertime, 25(OH)D levels were higher than in wintertime (17.9 vs. 15.0 ng/mL). A 1 µg/1000 kcal increase in vitamin D intake increased 25(OH)D levels by 0.170 ng/mL in wintertime and 0.149 ng/mL in summertime. iPTH levels reached a theoretical plateau corresponding to an 18.4 ng/mL 25(OH)D level. The vitamin D intake threshold for maintaining 25(OH)D levels at ≥20 and ≥18.4 ng/mL was ≥10.97 μg/day. For a sufficient level of 25(OH)D in young Korean women, increasing summertime UV irradiation time and increasing vitamin D supplements and vitamin D-containing foods throughout the year is beneficial.     

Vitamin D insufficiency in children, adolescents, and young adults with cystic fibrosis despite routine oral supplementation

BACKGROUND: Cystic fibrosis (CF) with pancreatic insufficiency is associated with poor absorption of fat and fat-soluble vitamins, including vitamin D. Pancreatic enzyme supplementation does not completely correct fat malabsorption in CF patients. OBJECTIVE: The objective of the study was to compare the vitamin D status of children, adolescents, and young adults with CF who were treated with routine vitamin D and pancreatic enzyme supplements with the vitamin D status of a healthy reference group from a similar geographic area. DESIGN: Growth, dietary intake, and serum concentrations of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)(2)D], and parathyroid hormone (PTH) were measured in 101 white subjects with CF and a reference group of 177 white subjects. RESULTS: The median daily vitamin D supplementation in the CF group was 800 IU. The mean +/- SD serum concentrations of 25(OH)D were 20.7 +/- 6.5 ng/mL in the CF group and 26.2 +/- 8.6 ng/mL in the reference group (P < 0.001). Vitamin D deficiency and insufficiency were defined as 25(OH)D concentrations < 11 ng/mL and < 30 ng/mL, respectively. Seven percent of the CF group and 2% of the healthy reference group were vitamin D deficient (P < 0.03). Ninety percent of the CF group and 74% of the healthy reference group were vitamin D insufficient (P < 0.01). Twenty-five percent of the CF group and 9% of the healthy reference group had elevated PTH (P < 0.006). The odds of vitamin D insufficiency in the CF group, compared with the healthy reference group, were 1.2 (95% CI: 1.1, 1.3) after adjustment for season and age. CONCLUSION: Despite daily vitamin D supplementation, serum 25(OH)D concentrations remain low in children, adolescents, and young adults with CF.     

Low 25(OH)D Level Is Associated with Severe Course and Poor Prognosis in COVID-19

We evaluated associations between serum 25-hydroxyvitamin D [25(OH)D] level and severity of new coronavirus infection (COVID-19) in hospitalized patients. We assessed serum 25(OH)D level in 133 patients aged 21–93 years. Twenty-five (19%) patients had severe disease, 108 patients (81%) had moderate disease, and 18 (14%) patients died. 25(OH)D level ranged from 3.0 to 97.0 ng/mL (median, 13.5 [25%; 75%, 9.6; 23.3] ng/mL). Vitamin D deficiency was diagnosed in 90 patients, including 37 with severe deficiency. In patients with severe course of disease, 25(OH)D level was lower (median, 9.7 [25%; 75%, 6.0; 14.9] ng/mL), and vitamin D deficiency was more common than in patients with moderate course (median, 14.6 [25%; 75%, 10.6; 24.4] ng/mL, p = 0.003). In patients who died, 25(OH)D was 9.6 [25%; 75%, 6.0; 11.5] ng/mL, compared with 14.8 [25%; 75%, 10.1; 24.3] ng/mL in discharged patients (p = 0.001). Severe vitamin D deficiency was associated with increased risk of COVID-19 severity and fatal outcome. The threshold for 25(OH)D level associated with increased risk of severe course was 11.7 ng/mL. Approximately the same 25(OH)D level, 10.9 ng/mL, was associated with increased risk of mortality. Thus, most COVID-19 patients have vitamin D deficiency; severe vitamin D deficiency is associated with increased risk of COVID-19 severity and fatal outcome.     

Vitamin D Deficiency in Cord Plasma from Multiethnic Subjects Living in the Tropics

Background: Vitamin D deficiency is commonly reported in high-latitude areas and in dark-pigmented individuals. However, nothing is known about vitamin D in cord blood from multiethnic subjects living in the tropics.

Objective: Our study objective was to determine the prevalence of vitamin D deficiency in summer and winter in cord blood from multiethnic individuals in Hawai’i where sufficient sun irradiance occurs year-round for cutaneous vitamin D production.

Methods: 25-Hydroxyvitamin D (25(OH)D) levels were quantified by enzyme immunoassay in 100 cord plasma samples from apparently healthy full-term newborns and their mothers. Stratification was performed by birth season and ethnicity.

Results: Mean 25(OH)D levels were 24.5 ng/mL (9.1–68.3 ng/mL). Overall, 28% of samples were vitamin D deficient (<20 ng/mL) and 50% were insufficient (20–30 ng/mL). 25(OH)D levels (ng/mL) were highest in Caucasians (30.5, n = 19), followed by Asians (25.1, n = 43), Hispanics (21.5, n = 3), Pacific Islanders (20.0, n = 25), and African Americans (19.6, n = 2). Differences among groups were significant (p = 0.008). Cord plasmas from summer versus winter were higher overall (p = 0.001) and among Asians (p = 0.0003). Seasonal changes were correlated with sun irradiance overall (r = 0.43, p = 0.0001), among Caucasians (r = 0.45, p = 0.05), and among Asians (r = 0.45, p = 0.0001).

Conclusion: Our results suggest that prenatal supplement recommendations of 400 IU vitamin D/day do not protect against vitamin D deficiency, even in subjects living in the tropics where ample sun irradiance exists for cutaneous vitamin D synthesis. The high prevalence of vitamin D deficiency we observed emphasizes the necessity for regular 25(OH)D monitoring, particularly during pregnancy and lactation, in dark-pigmented individuals, and during winter months.     

Vitamin D Insufficiency Among Postmenopausal Women in Urban and Rural Areas in Guilan,Northern Iran

This study aimed to describe vitamin D status in postmenopausal women in urban and rural areas in Guilan, northern Iran. Between October 2004 and February 2005 a group of 750 women older than 50 years was randomly selected from urban and rural areas in Guilan. The participants were interviewed to collect data on age, educational level, body weight, height, employment status, reproductive history, medications, history of illness, and supplement use. Serum 25(OH) D was measured in 646 women (427 in urban areas and 219 women in rural areas). Serum 25(OH) D levels in urban and rural postmenopausal women were 18.5 ± 13.5 ng/ml and 22.9 ± 13.8 ng/ml (P < 0.0001), respectively. In urban and rural areas, 84.7% and 79.5% of the women had serum 25(OH) D levels less than 30 ng/ml, respectively. In this study, serum vitamin D levels and prevalence of vitamin D insufficiency was related to educational level in urban women. The urban women in the lowest educational level (<5 years schooling) had a better vitamin D status than other educational groups. This study showed that a high proportion of postmenopausal women living in Guilan province had vitamin D insufficiency. Vitamin D inadequacy was more common in urban areas and especially in the upper social class. Supplement use and national strategies to prevent vitamin D insufficiency are strongly needed in this community.     

Association of modifiable and nonmodifiable factors with vitamin D status in pregnant women and neonates in Oakland, CA

There is little information on the contribution of modifiable vs nonmodifiable factors to maternal and neonatal vitamin D status in temperate regions of the United States. The purpose of this cross-sectional observation study conducted between December 2006 and February 2008 was to identify associations between observed and measured maternal characteristics and vitamin D status at term in pregnant women and their infants in a multiethnic community in Oakland, CA. Two hundred seventy-five pregnant women aged 18 to 45 years and carrying a singleton fetus were recruited and data from 210 mother-infant pairs were included in analyses. Analysis of covariance identified predictors of maternal and cord serum 25-hydroxyvitamin D [25(OH)D] in a multivariate model considering vitamin D intake, lifestyle factors, and skin pigmentation. Maternal serum 25(OH)D was significantly associated with season of delivery (P=0.0002), average daily D intake (P=0.0008), right upper inner arm pigmentation (P=0.0035), and maternal pre- or early-pregnancy body mass index (calculated as kg/m²) (P=0.0207). The same factors were significant for cord serum 25(OH)D, which was highly correlated with maternal serum 25(OH)D (r=0.79; P<0.0001). During the year, 54% of mothers and 90% of neonates had 25(OH)D <30 ng/mL (<75 nmol/L). Of women taking daily prenatal vitamin/mineral supplements (400 IU vitamin D), 50.7% had serum 25(OH)D <30 ng/mL (<75 nmol/L). In conclusion, 25(OH)D <30 ng/mL (<75 nmol/L) was prevalent in mothers and neonates across racial groups and seasons, and vitamin D status was associated with both modifiable and nonmodifiable risk factors.     

Vitamin D status: effects on quality of life in osteoporosis among Turkish women

Background and objectives Vitamin D deficiency causes muscle weakness, impairs bone formation and neuromuscular coordination thus leading to an increase in fracture risk. It has been found that inadequate levels of vitamin D are present in most of the osteoporosis patients. However, very few studies investigate the association between vitamin D status and quality of life (QOL). The aim of this study is to investigate the effects of vitamin D on QOL among Turkish women with osteoporosis. Methods 259 patients (61.0 ± 8.9 years) with osteoporosis were evaluated by physical activity level, back pain, bone turnover markers, 25-hydroxyvitamin D [25(OH)D], parathyroid hormone levels and bone mineral density. QOL was assessed using QOL Questionnaire of the European Foundation for Osteoporosis (QUALEFFO). 25(OH)D levels below 20 ng/ml was defined as vitamin D insufficiency, below 12 ng/ml as vitamin D deficiency. Results Mean 25(OH)D level was 22.7 ± 12.6 ng/ml and mean total QUALEFFO score was 43.3 ± 14.9. Vitamin D levels were significantly correlated with all subscales and total score of QUALEFFO (r = −0.25, P = 0.0001). Vitamin D insufficiency was determined in 132 patients (51%). In vitamin D deficient (<12 ng/ml) group all subscales and total QOL were found to be poorer when compared with the groups whose vitamin D levels were ≥12 and <20 ng/ml and ≥20 ng/ml (effect sizes 0.41 and 0.62 respectively, P = 0.0001 for total QOL). Vitamin D level, education, concomitant diseases, physical activity level and pain severity were found to be significantly associated with QOL in multiple linear regression analysis model. Conclusions Vitamin D insufficiency affects physical, social and mental functions of osteoporosis patients and impairs QOL. Vitamin D was found to be one of the factors affecting QOL.