Effects of Vitamin C Supplementation on Plasma and Urinary Vitamin C Concentration in Korean Women.
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ABSTRACT:
SUBMITTER: Choi J
PROVIDER: S-EPMC5539213 | biostudies-other | 2017 Jul
REPOSITORIES: biostudies-other
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Project description:ContextSerum 25-hydroxyvitamin D (25OHD) is lower in women with darker skin color. Is it due to lower skin production, lower absorption, or different metabolism of vitamin D?ObjectivesThe objective of the study was to measure the effect of vitamin D3 on serum 25OHD and serum PTH in older African American women with vitamin D insufficiency and the serum 25OHD 20 ng/mL or less (<50 nmol/L). The results can be used to estimate the Recommended Dietary Allowance (RDA).Design and settingThis was a randomized, double-blind placebo trial at Creighton University Medical Center and Indiana University Medical Center.ParticipantsParticipants were 110 healthy older African American women.InterventionsThe intervention consisted of participants randomly assigned to placebo, vitamin D3 400, 800, 1600, 2400, 3200, 4000, or 4800 IU daily; calcium supplements were given to maintain total calcium intake of 1200-1400 mg/d.Main outcome measurementsChange in serum 25OHD and serum PTH levels at 12 months was measured.ResultsMean baseline serum 25OHD was 13 ng/mL (33 nmol/L). On 4800 IU, serum 25OHD averaged 50 ng/mL (125 nmol/L) compared with 47 ng/mL (117 nmol/L) in Caucasian women. Serum PTH at 12 months decreased significantly (P = .008) when related to serum 25OHD but not dose. Hypercalcemia occurred in 7% and hypercalciuria in 15%. Events were unrelated to vitamin D dose.ConclusionVitamin D3 800 IU increased serum 25OHD greater than 20 ng/mL (>50 nmol/L) in 97.5% of the African American women just as it did in the Caucasian women, and therefore, the RDA is the same for both groups. Because absorption and metabolism of oral vitamin D absorption is similar in both groups, lower levels of serum 25OHD in African Americans must be due to lower production of vitamin D in skin.
| S-EPMC3590472 | biostudies-literature
Project description: Not available
| S-EPMC8407451 | biostudies-literature
Project description:BackgroundObservational studies among older women have associated vitamin D insufficiency with a greater prevalence and incidence of urinary incontinence. However, little is known about the effect of vitamin D supplementation in reducing urinary incontinence.ObjectiveThis study aimed to evaluate the effects of vitamin D supplementation in reducing the frequency of urinary incontinence in older women.Study designWe conducted an ancillary study of women aged ≥55 years in the Vitamin D and Omega-3 Trial, a randomized trial with a 2×2 factorial design. Recruitment of participants started from 2011 to 2014 across 50 US states, and the follow-up of participants ended in January 2018. Randomized treatments in the parent study included (1) vitamin D3 (cholecalciferol) at a dosage of 2000 IU/d, (2) marine omega-3 fatty acids at a dosage of 1 g/d, and (3) matching placebo. Here, we analyzed women according to their randomization to vitamin D supplementation or placebo, regardless of treatment with omega-3 fatty acid supplementation. Validated frequency of urinary incontinence questions were added in year 2 of the study and were used again in year 5 at the end of trial. Prespecified ancillary outcomes included the prevalence of urinary incontinence at years 2 and 5, along with incident incontinence and progression of incontinence (from lower to higher frequency) from year 2 to year 5. Preplanned subgroup analyses examined the following outcomes: prerandomization of low serum levels of vitamin D (serum 25-hydroxyvitamin D<20 ng/mL), incontinence types, weight categories, and African American race.ResultsAmong the randomized women who provided urinary incontinence data, 11,646 women at year 2 and 10,527 women at year 5, the mean age was 70 years at year 2, with 29% racial and ethnic minorities. The prevalence of urinary incontinence that occurred at least weekly was 29% at year 2 and increased to 37% at year 5. Vitamin D supplementation compared to with placebo was not associated with lower odds of urinary incontinence occurring at least weekly at year 2 (odds ratio, 1.08; 95% confidence interval, 0.99-1.19) or year 5 (odds ratio, 1.04; 95% confidence interval, 0.94-1.15). Vitamin D supplementation compared to placebo was not associated with lower incidence or progression of urinary incontinence from year 2 to year 5: incidence (odds ratio, 1.06; 95% confidence interval, 0.83-1.35) or progression (odds ratio, 0.94; 95% confidence interval, 0.82-1.08). Women with prerandomization of low serum levels of vitamin D (n=836) did not have lower odds of the prevalence, incidence, or progression of urinary incontinence. The findings were null in subgroups according to incontinence type, women with obesity, and African American women. Only women with healthy weight randomized to vitamin D had lower odds of progression of urinary incontinence (odds ratio, 0.78; 95% confidence interval, 0.63-0.95; P=.01).ConclusionVitamin D supplementation compared to placebo for 2 to 5 years was not associated with differences in the prevalence, incidence, or progression of urinary incontinence in older women with and without adequate serum vitamin D levels, with inconsistent differences among subgroups. The findings showed that the broad use of moderate doses of vitamin D supplementation did not reduce urinary incontinence in older women.
| S-EPMC8983596 | biostudies-literature
Project description:Hormonal fluctuations, excessive clothing covering, sunscreen use, changes in body fat composition, a vitamin D-deficient diet, and a sedentary lifestyle can all predispose postmenopausal women to vitamin D deficiency. An effective supplementation plan requires a thorough understanding of underlying factors to achieve the desired therapeutic concentrations. The objective of this study was to conduct a systematic review of the predictors that affect vitamin D status in postmenopausal women. From inception to October 2022, we searched MEDLINE, Embase, Web of Science, Scopus, and clinical trial registries. Randomized clinical trials of postmenopausal women taking supplements of vitamin D with serum 25-hydroxyvitamin D (25(OH)D) measurement as the trial outcome were included. Two independent reviewers screened selected studies for full-text review. The final assessment covered 19 trials within 13 nations with participants aged 51 to 78. Vitamin D supplementation from dietary and pharmaceutical sources significantly increased serum 25(OH)D to optimal levels. Lower baseline serum 25(OH)D, lighter skin color, longer treatment duration, and prolonged skin exposure were all associated with a better response to vitamin D supplementation in postmenopausal women.
| S-EPMC9919965 | biostudies-literature
Project description:BackgroundVitamin D deficiency or insufficiency is thought to be common among pregnant women. Vitamin D supplementation during pregnancy has been suggested as an intervention to protect against adverse gestational outcomes.ObjectivesTo examine whether supplements with vitamin D alone or in combination with calcium or other vitamins and minerals given to women during pregnancy can safely improve maternal and neonatal outcomes.Search methodsWe searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2011), the International Clinical Trials Registry Platform (ICTRP) (31 October 2011), the Networked Digital Library of Theses and Dissertations (28 October 2011) and also contacted relevant organisations (8 April 2011).Selection criteriaRandomised and quasi-randomised trials with randomisation at either individual or cluster level, evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy.Data collection and analysisTwo review authors independently i) assessed the eligibility of studies against the inclusion criteria ii) extracted data from included studies, and iii) assessed the risk of bias of the included studies. Data were checked for accuracy.Main resultsThe search strategy identified 34 potentially eligible references. We included six trials assessing a total of 1023 women, excluded eight studies, and 10 studies are still ongoing. Five trials involving 623 women compared the effects of vitamin D alone versus no supplementation/placebo and one trial with 400 women compared the effects of vitamin D and calcium versus no supplementation.Only one trial with 400 women reported on pre-eclampsia: women who received 1200 IU vitamin D along with 375 mg of elemental calcium per day were as likely to develop pre-eclampsia as women who received no supplementation (average risk ratio (RR) 0.67; 95% confidence interval (CI) 0.33 to 1.35). Data from four trials involving 414 women consistently show that women who received vitamin D supplements had higher concentrations of vitamin D in serum at term than those women who received no intervention or a placebo; however the magnitude of the response was highly heterogenous. Data from three trials involving 463 women suggest that women who receive vitamin D supplements during pregnancy less frequently had a baby with a birthweight below 2500 grams than those women receiving no treatment or placebo; statistical significance was borderline (RR 0.48; 95% CI 0.23 to 1.01).In terms of other conditions, there were no significant differences in adverse side effects including nephritic syndrome (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women); stillbirths (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women) or neonatal deaths (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women) between women who received vitamin D supplements in comparison with women who received no treatment or placebo. No studies reported on preterm birth, maternal death, admission to neonatal intensive care unit/special nursery or Apgar scores.Authors' conclusionsVitamin D supplementation in a single or continued dose during pregnancy increases serum vitamin D concentrations as measured by 25-hydroxyvitamin D at term. The clinical significance of this finding and the potential use of this intervention as a part of routine antenatal care are yet to be determined as the number of high quality trials and outcomes reported is too limited to draw conclusions on its usefulness and safety. Further rigorous randomised trials are required to evaluate the role of vitamin D supplementation in pregnancy.
| S-EPMC3747784 | biostudies-literature
Project description:Few studies have prospectively examined predictors of change in plasma concentrations of 25-hydroxyvitamin D [25(OH)D]. We sought to determine the predictors of 5-y change in 25(OH)D. Plasma 25(OH)D concentrations were assessed at baseline (1997-2000) and 5 y later (2002-2005) in 668 postmenopausal women enrolled in the Osteoporosis and Periodontal Disease Study. Baseline and changes in demographic, dietary, lifestyle, and health-related factors were tested as predictors of change in 25(OH)D concentrations by using multivariable linear regression. The mean 5-y change in 25(OH)D (mean ± SD) was 7.7 ± 0.7 nmol/L (P < 0.001). In our predictive model (n = 643), predictors explained 31% of the variance in change in 25(OH)D concentrations and included baseline 25(OH)D, baseline and change in vitamin D supplementation and physical activity, change in season of blood draw, BMI, whole-body T score, and baseline hormone therapy use. Baseline 25(OH)D and change in vitamin D supplementation explained the most variation (25%) in 25(OH)D. Exploratory analyses showed a borderline significant interaction between tertiles of baseline 25(OH)D and change in vitamin D supplementation over time (P = 0.06). The greatest mean increase in 25(OH)D (22.9 ± 16.8 nmol/L), with adjustment for other statistically significant predictors, occurred in women whose baseline 25(OH)D concentration was ≤51.0 nmol/L (tertile 1) and who increased supplementation use over time. These results confirm the importance of supplementation in increasing 25(OH)D concentrations in aging women, even after other statistically significant predictors are controlled for. These data also suggest that this is especially true among aging women with inadequate 25(OH)D (e.g., <50 nmol/L).
| S-EPMC3417832 | biostudies-literature
Project description:The aim of the study was to compare the effects of vitamin D3 supplementation versus placebo on serum sex hormones in postmenopausal women completing a 12-month diet + exercise weight loss program.Two hundred eighteen overweight or obese women (50-75 y) with serum 25-hydroxyvitamin D at least 10 to less than 32?ng/mL ("insufficient") were randomized to either weight loss + 2,000?IU/day oral vitamin D3, or to weight loss + daily placebo. Serum sex hormone-binding globulin, estrone, total, free, and bioavailable estradiol, and testosterone were measured by radioimmunoassay before randomization and at 12 months. Mean changes were compared between groups (intent-to-treat) using generalized estimating equations.The 12-month changes in sex hormone-binding globulin, estrone, total, free, and bioavailable estradiol, and testosterone did not differ between groups (all P?>?0.05). However, a greater increase in serum 25-hydroxyvitamin D was associated with a greater increase in sex hormone-binding globulin (Ptrend?=?0.01), and larger decreases in free and bioavailable estradiol (Ptrend?=?0.04, Ptrend?=?0.03, respectively). In post-hoc analyses, we compared women randomized to vitamin D whose serum 25-hydroxyvitamin D remained insufficient (n?=?38), to women who became replete (25-hydroxyvitamin D ?32?ng/mL; n?=?53). Replete women showed greater reductions in bioavailable estradiol (-1.8 vs -0.7?pg/mL), free testosterone (-0.8 vs -0.3?pg/mL), and bioavailable testosterone (-1.8 vs -0.6?ng/dL), and a greater increase in sex hormone-binding globulin (10.6 vs 4.7?nmol/L) (all P?<?0.05), even after adjusting for differences in total 12-month weight loss.Overall, 12-month changes in sex hormone did not differ between groups. However, vitamin D repletion was associated with greater reductions in sex hormones during weight loss, with a possible dose-dependent effect. Future studies should test higher doses and target circulating 25-hydroxyvitamin D levels when measuring such effects.
| S-EPMC4874908 | biostudies-literature
Project description:Increasing evidence describes a possible interplay between vitamin D insufficiency with increased aldosterone. The authors sought to evaluate the effect of vitamin D supplementation on plasma aldosterone concentration (PAC) in patients with hypertension and 25-hydroxyvitamin D[25(OH)D] insufficiency. The Styrian Vitamin D Hypertension Trial was a single-center, double-blind, placebo-controlled randomized clinical trial conducted from 2011 to 2014. Two hundred patients with arterial hypertension and 25(OH)D levels <30 ng/mL were enrolled. Study participants were randomized to receive either 2800 IU of vitamin D3 or placebo. The present investigation is a post hoc analysis using analysis of covariance adjusting for baseline differences. A total of 188 participants (mean±standard deviation age, 60.1±11.3 years; 47% women; 25(OH)D, 21.2±5.6 ng/mL) completed the trial. Mean differences between baseline and follow-up PAC in the control and intervention arm were +3.3 ng/dL and +0.9 ng/dL, respectively (P=.04). The findings indicate that vitamin D3 supplementation significantly decreases PAC in patients with arterial hypertension and 25(OH)D insufficiency.
| S-EPMC8032175 | biostudies-literature
Project description:BackgroundOrganophosphate compounds are commonly used in residential furniture, electronics, and baby products as flame retardants and are also used in other consumer products as plasticizers. Although the levels of exposure biomarkers are generally higher among children and decrease with age, relatively little is known about the individual characteristics associated with higher levels of exposure. Here, we investigate urinary metabolites of several organophosphate flame retardants (PFRs) in a cohort of pregnant women to evaluate patterns of exposure.MethodsPregnant North Carolina women (n=349) provided information on their individual characteristics (e.g. age and body mass index (BMI)) as a part of the Pregnancy Infection and Nutrition Study (2002-2005). Women also provided second trimester urine samples in which six PFR metabolites were measured using mass spectrometry methods.ResultsPFR metabolites were detected in every urine sample, with BDCIPP, DHPH, ip-PPP and BCIPHIPP detected in >80% of samples. Geometric mean concentrations were higher than what has been reported previously for similarly-timed cohorts. Women with higher pre-pregnancy BMI tended to have higher levels of urinary metabolites. For example, those classified as obese at the start of pregnancy had ip-PPP levels that were 1.52 times as high as normal weight range women (95% confidence interval: 1.23, 1.89). Women without previous children also tended to have higher urinary levels of DPHP, but lower levels of ip-PPP. In addition, we saw strong evidence of seasonal trends in metabolite concentrations (e.g. higher DPHP, BDCIPP, and BCIPHIPP in summer, and evidence of increasing ip-PPP between 2002 and 2005).ConclusionsOur results indicate ubiquitous exposure to PFRs among NC women in the early 2000s. Additionally, our work suggests that individual characteristics are related to exposure and that temporal variation, both seasonal and annual, may exist.
| S-EPMC5127734 | biostudies-literature
Project description:IntroductionThe aim of the study was to identify the consumption of vitamin and folic acid supplements before and during pregnancy in a group of post-partum women (Romanian, Hungarian, and Roma) from Mureș County, Romania, and the influence of socio-economic and behavioral factors on the consumption of vitamins.Materials and methodsThis cross-sectional questionnaire-based study included 1278 post-partum women (during the three days of hospitalization for birth), average age 29.5, registered for giving birth in the three hospitals in Mureș County, 2015-2016.ResultsIn our sample, 69.58% of the interviewed women did not use any vitamin and folic acid supplements before pregnancy, while 30.70% did not use vitamin supplements during pregnancy. The lack of vitamin supplementation during pregnancy was associated with the low birth weight (<2500 g) of newborns (OR = 2.4, 95% CI [1.6-3.8]) and birth at under 36 weeks of gestation (OR = 0.5, 95% CI [0.2-0.8]).ConclusionThe use of vitamin supplements, including folic acid, continues to be deficient among Romanian women before getting pregnant, as well as during their pregnancy. We observed a lack of vitamin supplementation for pregnant women even if they were influenced by risk factors. This highlights the importance of promoting the benefits of vitamin supplementation equally among all subjects.
| S-EPMC9318761 | biostudies-literature