Randomised Controlled Trials Of Vitamin Research Articles

The effectiveness of interventions to reduce the transmission of acute respiratory infections in care homes: a systematic review.

Care home residents are at high risk from outbreaks of respiratory infections, such as influenza and COVID-19. We conducted a systematic review of randomized controlled trials, to determine which interventions (apart from vaccines) are effective at reducing transmission of acute respiratory illnesses (ARIs) in care homes. We searched CINAHL, Medline, Embase and Cochrane for randomized controlled trials (RCTs) of interventions to prevent transmission of ARIs in care homes (excluding vaccines), to April 2023. A total of 21 articles met inclusion criteria. Two infection control interventions significantly reduced respiratory infections. Oseltamivir significantly reduced risk of symptomatic laboratory-confirmed influenza (OR 0.39, 95%CI 0.16-0.94, three trials), and influenza-like illness (OR 0.50, 95%CI 0.36-0.69), even in a vaccinated population. High dose vitamin D supplementation reduced incidence of ARIs (incidence rate ratio 0.60; 95%CI 0.38-0.94, one trial). Nine other RCTs of vitamin, mineral, probiotic and herbal supplements showed no significant effect. Transmission of respiratory infections in care homes can be reduced by educational interventions to improve infection control procedures and compliance by staff, by antiviral prophylaxis soon after a case of influenza has been detected, and by supplementation with high-dose Vitamin D3. Further research is needed to confirm the effect of high-dose Vitamin D3.

The outcome of IV vitamin C therapy in patients with sepsis or septic shock: a meta-analysis of randomized controlled trials

BackgroundTo update a meta-analysis of randomized controlled trials (RCTs) and further explore the outcome of IV vitamin C (IVVC) administration in sepsis or septic shock patients.MethodsThis study is a meta-analysis of RCTs. The RCTs of vitamin C therapy in sepsis or septic shock were searched in PubMed, EMBASE and Clinical Trials.gov from inception to January 16, 2023. We registered the protocol with PROSPERO (CRD42022354875). The primary outcome was delta Sequential Organ Failure Assessment (SOFA) score at 72–96 h. Two reviewers independently assessed RCTs according to eligibility criteria: (1) study type: RCT; (2) patient population: patients ≥ 18 years with sepsis or septic shock; (3) intervention: IVVC at any doses as monotherapy or combined with thiamine or and hydrocortisone compared with standard of care, no intervention or placebo (defined as control group); (4) the RCT described short-term mortality or SOFA score. Then, two authors independently extracted related information from RCTs.ResultsEighteen RCTs (n = 3364 patients) were identified in this meta-analysis. There were significant effects in the delta SOFA score from baseline to 72–96 h (MD, − 0.62; 95% CI, − 1.00 to − 0.25; p = 0.001) and the duration of vasopressor use (MD, − 15.07; 95% CI, − 21.59 to − 8.55; p < 0.00001) with IVVC therapy. Treatment with IVVC was not shown to improve short-term mortality (OR, 0.89; 95% CI, 0.77 to 1.04; p = 0.14); nevertheless, dose at 25–100 mg/kg/d subgroup associated with a significant reduction in short-term mortality (OR, 0.80; 95% CI, 0.65 to 0.97; p = 0.03). An increase adverse event was observed in IVVC therapy (OR, 1.98; 95% CI, 1.06 to 3.68; p = 0.03).ConclusionIn this meta-analysis, IVVC in sepsis or septic shock patients significantly improved delta SOFA score and reduced the duration of vasopressor use, whereas it was not associated with reduction in short-term mortality and had higher adverse events.

Is antenatal or early-life vitamin D associated with eczema or food allergy in childhood? A systematic review.

To summarise the associations between antenatal or early-life blood vitamin D and the development of eczema/food allergy in childhood. A systematic review and meta-analyses were conducted to synthesize the published literature. Two reviewers independently performed the study selection and data extraction on Covidence. We assessed the risk of bias for observational studies by using the Newcastle-Ottawa Scale and the Cochrane Risk of Bias tool for clinical trials. The certainty of the evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluations (GRADE). We systematically searched PubMed and Embase from inception and April 2022. Human studies that investigated prospective associations between antenatal or early-life blood vitamin D levels, dietary intake or supplementation and childhood eczema/food allergy. Forty-three articles including six randomised controlled trials (RCTs) were included. Four RCTs of vitamin D supplementation during pregnancy showed no evidence of an effect on the incidence of eczema (pooled odds ratio [OR]=0.85; 0.67-1.08, I2 = 6.7%, n= 2074). Three RCTs reported null associations between supplementation in pregnancy/infancy and food allergy. From six cohort studies, increasing cord blood vitamin D levels were associated with reduced prevalence of eczema at/close to age one (OR per 10 nmol/L increase=0.89; 0.84-0.94, I2 = 0%, 2025 participants). We found no evidence of an association between maternal antenatal or infant vitamin D level or dietary intake and the development of food allergy or eczema in offspring. We found an association between higher vitamin D levels in cord blood and reduced risk of eczema in cohort studies. Further trials with maternal and infant supplementation are needed to confirm if vitamin D supplementation can effectively prevent eczema or food allergy in childhood. PROSPERO, No. CRD42013005559.

Comparing the Evidence from Observational Studies and Randomized Controlled Trials for Nonskeletal Health Effects of Vitamin D.

Although observational studies of health outcomes generally suggest beneficial effects with, or following, higher serum 25-hydroxyvitamin D [25(OH)D] concentrations, randomized controlled trials (RCTs) have generally not supported those findings. Here we review results from observational studies and RCTs regarding how vitamin D status affects several nonskeletal health outcomes, including Alzheimer’s disease and dementia, autoimmune diseases, cancers, cardiovascular disease, COVID-19, major depressive disorder, type 2 diabetes, arterial hypertension, all-cause mortality, respiratory tract infections, and pregnancy outcomes. We also consider relevant findings from ecological, Mendelian randomization, and mechanistic studies. Although clear discrepancies exist between findings of observational studies and RCTs on vitamin D and human health benefits these findings should be interpreted cautiously. Bias and confounding are seen in observational studies and vitamin D RCTs have several limitations, largely due to being designed like RCTs of therapeutic drugs, thereby neglecting vitamin D’s being a nutrient with a unique metabolism that requires specific consideration in trial design. Thus, RCTs of vitamin D can fail for several reasons: few participants’ having low baseline 25(OH)D concentrations, relatively small vitamin D doses, participants’ having other sources of vitamin D, and results being analyzed without consideration of achieved 25(OH)D concentrations. Vitamin D status and its relevance for health outcomes can usefully be examined using Hill’s criteria for causality in a biological system from results of observational and other types of studies before further RCTs are considered and those findings would be useful in developing medical and public health policy, as they were for nonsmoking policies. A promising approach for future RCT design is adjustable vitamin D supplementation based on interval serum 25(OH)D concentrations to achieve target 25(OH)D levels suggested by findings from observational studies.

Evaluating the Evidence in Clinical Studies of Vitamin D in COVID-19.

Laboratory evidence provides a biological rationale for the benefits of vitamin D in COVID-19, and vitamin D supplementation is associated with reduced risk of respiratory infections. Most of the clinical studies of vitamin D in COVID-19 have been observational, and the most serious problem with observational study design is that of confounding. Observational studies typically assess the relationship of 25(OH)D values with COVID-19 outcomes. Many conditions associated with low vitamin D status are also associated with worse COVID-19 outcomes. Randomized controlled trials (RCTs) overcome the problem of confounding, typically comparing outcomes between groups receiving vitamin D supplementation or placebo. However, any benefit of vitamin D in COVID-19 may be related to the dose, duration, daily vs. bolus administration, interaction with other treatments, and timing of administration prior to or during the illness. Serum 25(OH)D values >50 nmol/L have been associated with reduced infection rates, severity of COVID-19, and mortality in observational studies. Few RCTs of vitamin D supplementation have been completed, and they have shown no benefit of vitamin D in hospitalized patients. Vitamin D may benefit those with mild or asymptomatic COVID-19, and those with greater 25(OH)D values may have lower risk of acquiring infection. Because those at greatest risk of COVID-19 are also at greatest risk of vitamin D deficiency, it is reasonable to recommend vitamin D supplementation 15–20 mcg (600–800 IU) daily for the general population during the COVID-19 pandemic. Vitamin D doses greater than 100 mcg (4000 IU) daily should not be used without monitoring serum 25(OH)D and calcium.

Assessment of research waste part 2: wrong study populations- an exemplar of baseline vitamin D status of participants in trials of vitamin D supplementation

BackgroundResearch waste can occur when trials are conducted in the wrong populations. Vitamin D deficient populations are most likely to benefit from vitamin D supplementation. We investigated waste attributable to randomised controlled trials (RCTs) of supplementation in populations that were not vitamin D deficient.MethodsIn December 2015, we searched Pubmed, recent systematic reviews, and three trial registries for RCTs of vitamin D with clinical endpoints in adults, and 25-hydroxvitamin D (25OHD) survey data relevant to large (N ≥ 1000) RCTs. We investigated the proportion of RCTs that studied vitamin D deficient populations, temporal trends in baseline 25OHD, and whether investigators in large RCTs considered relevant 25OHD survey data or systematic reviews in their trial justifications.ResultsOf 137 RCTs of vitamin D with clinical endpoints, 118 (86%) reported baseline mean/median 25OHD, which was < 25, 25–49, 50–74, and ≥ 75 nmol/L in 12 (10%), 62 (53%), 36 (31%), and 8 (7%) RCTs, respectively. In 70% of RCTs, baseline 25OHD was > 40 nmol/L. Baseline 25OHD increased over time. Before 2006, 38%, 62%, 0% and 0% of RCTs had baseline 25OHD < 25, 25–49, 50–74, and ≥ 75 nmol/L respectively; in 2011–15, the respective proportions were 9%, 49%, 37%, and 6%. Of 12 RCTs with baseline 25OHD < 25 nmol/L, 8 had neutral findings. Of 25 large RCTs (18 completed, 7 ongoing), 1 was undertaken in a vitamin D deficient population, 3 in vitamin D insufficient populations, and 17 had, or probably will have, baseline 25OHD > 40 nmol/L. 44% (8/18) of large completed RCTs cited relevant prior population 25OHD data, and only 3/10 (30%) relevant prior systematic reviews.ConclusionsUp to 70% of RCTs of vitamin D with clinical endpoints, 71% of large completed RCTs, and 100% of ongoing large RCTs could be considered research waste because they studied cohorts that were not vitamin D deficient.

Feasibility of a randomized controlled trial of vitamin D vs. placebo in women with recently diagnosed breast cancer

Low serum vitamin D levels have been associated with poor outcomes in women diagnosed with early breast cancer. However, no randomized controlled trials (RCTs) have been performed to determine whether vitamin D supplementation might be an effective intervention in this population. We prospectively evaluated vitamin D adequacy and supplementation rates in a contemporary cross-sectional sample of breast cancer patients from 2 large urban centers and examined the feasibility of an RCT of vitamin D supplementation. Women with recently diagnosed early breast cancer were prospectively identified and recruited in Toronto and Los Angeles between March 2009 and January 2010. Anthropometric measurements, dietary, lifestyle, and medication histories were obtained by means of structured questionnaires and interviews. Tumor and treatment characteristics were abstracted from clinical records and blood samples were collected for analysis of 25-OH vitamin D. 173 eligible patients (median age 57) were enrolled. Clinical and treatment characteristics were similar between centres. 84.4 % of women reported use of vitamin D-containing supplements with median daily doses of 1,400 IU. Median 25-OH vitamin D levels were 85.5 and 98.5 nmol/L (P = 0.1), and levels of deficiency (<50 nmol/L), insufficiency (50-72 nmol/L), and adequacy (>72 nmol/L) were 3.8, 23.8, 72.5 % (Toronto) and 4.3, 20.7, 75 % (Los Angeles). 25-OH vitamin D levels were strongly correlated with vitamin D supplement use (r = 0.41, P < 0.0001). 68 % of women expressed willingness to participate in a vitamin D supplementation RCT; however, only 12.7 % of the study population met the pre-specified feasibility criteria (25-OH vitamin D <72 nmol/L, willing to participate, and taking ≤1,000 IU vitamin D supplement/day). Both vitamin D levels and supplementation rates are higher than in previous reports. While the majority of women would be willing to participate in an RCT of vitamin D supplementation, low levels of deficiency/insufficiency and high rates of supplement use would limit the feasibility of such a study.

Cochrane Review: Vitamin D supplementation for improving bone mineral density in children

AbstractBackgroundResults of randomised controlled trials (RCTs) of vitamin D supplementation to improve bone density in children are inconsistent.ObjectivesTo determine the effectiveness of vitamin D supplementation for improving bone mineral density in children, whether any effect varies by sex, age or pubertal stage, the type or dose of vitamin D given or baseline vitamin D status, and if effects persist after cessation of supplementation.Search methodsWe searched the Cochrane Central Register of Controlled Trials (CENTRAL Issue 3, 2009), MEDLINE (1966 to present), EMBASE (1980 to present), CINAHL (1982 to present), AMED (1985 to present) and ISI Web of Science (1945 to present) on 9 August 2009, and we handsearched key journal conference abstracts.Selection criteriaPlacebo‐controlled RCTs of vitamin D supplementation for at least three months in healthy children and adolescents (aged from one month to &lt; 20 years) with bone density outcomes.Data collection and analysisTwo authors screened references for inclusion, assessed risk of bias, and extracted data. We conducted meta‐analyses and calculated standardised mean differences (SMD) of the percent change from baseline in outcomes in treatment and control groups. We performed subgroup analyses by sex, pubertal stage, dose of vitamin D and baseline serum vitamin D and considered these as well as compliance and allocation concealment as possible sources of heterogeneity.Main resultsWe included six RCTs (343 participants receiving placebo and 541 receiving vitamin D) for meta‐analyses. Vitamin D supplementation had no statistically significant effects on total body bone mineral content (BMC), hip bone mineral density (BMD) or forearm BMD. There was a trend to a small effect on lumbar spine BMD (SMD 0.15, 95% CI ‐0.01 to 0.31, P = 0.07). There were no differences in effects between high and low serum vitamin D studies at any site though there was a trend towards a larger effect with low vitamin D for total body BMC (P = 0.09 for difference). In low serum vitamin D studies, significant effects on total body BMC and lumbar spine BMD were approximately equivalent to a 2.6% and 1.7 % percentage point greater change from baseline in the supplemented group.Authors' conclusionsThese results do not support vitamin D supplementation to improve bone density in healthy children with normal vitamin D levels, but suggest that supplementation of deficient children may be clinically useful. Further RCTs in deficient children are needed to confirm this.Plain Language SummaryVitamin D for improving bone density in childrenThis summary of a Cochrane Review, presents what we know from research about the effect of vitamin D supplements on bone density in children.The review shows that in healthy children generally, vitamin D supplementation does not improve bone density at the hip, lumbar spine, forearm or in the body as a whole.Some of the evidence suggests that vitamin D supplements may improve bone density in children who have low levels of vitamin D but this is uncertain.We do not have precise information about side effects and complications but the available information suggests that vitamin D supplements are well tolerated.What is osteoporosis and what is vitamin D?Osteoporosis is a condition where bones are weak, brittle and break easily. The risk of osteoporosis and fractures (breaks) in later life depends on how much bone is built when a child and how much bone is lost when an adult. One way to prevent osteoporosis and fractures in later life is to build stronger bones when young. Vitamin D plays an important role in improving the body's absorption of calcium from food, reducing losses of calcium from the body and getting calcium deposited into to bone to improve the quantity of bone developed. Therefore it is thought that if vitamin D levels in the body are low in childhood, less bone will be developed and that improving vitamin D levels by supplements would result in more bone being developed. Bone density is a major measure of bone strength and the amount of bone mineral present at different sites and so is used to measure the effects of interventions, like vitamin D supplementation, to improve bone health.

Vitamin D supplementation for improving bone mineral density in children

Background: Results of randomised controlled trials (RCTs) of vitamin D supplementation to improve bone density in children are inconsistent. Objectives: To determine the effectiveness of vitamin D supplementation for improving bone mineral density in children, whether any effect varies by sex, age or pubertal stage, the type or dose of vitamin D given or baseline vitamin D status, and if effects persist after cessation of supplementation. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL Issue 3, 2009), MEDLINE (1966 to present), EMBASE (1980 to present), CINAHL (1982 to present), AMED (1985 to present) and ISI Web of Science (1945 to present) on 9 August 2009, and we handsearched key journal conference abstracts. Selection criteria: Placebo-controlled RCTs of vitamin D supplementation for at least three months in healthy children and adolescents (aged from one month to Data collection and analysis: Two authors screened references for inclusion, assessed risk of bias, and extracted data. We conducted meta-analyses and calculated standardised mean differences (SMD) of the percent change from baseline in outcomes in treatment and control groups. We performed subgroup analyses by sex, pubertal stage, dose of vitamin D and baseline serum vitamin D and considered these as well as compliance and allocation concealment as possible sources of heterogeneity. Main results: We included six RCTs (343 participants receiving placebo and 541 receiving vitamin D) for meta-analyses. Vitamin D supplementation had no statistically significant effects on total body bone mineral content (BMC), hip bone mineral density (BMD) or forearm BMD. There was a trend to a small effect on lumbar spine BMD (SMD 0.15, 95% CI -0.01 to 0.31, P = 0.07). There were no differences in effects between high and low serum vitamin D studies at any site though there was a trend towards a larger effect with low vitamin D for total body BMC (P = 0.09 for difference). In low serum vitamin D studies, significant effects on total body BMC and lumbar spine BMD were approximately equivalent to a 2.6% and 1.7 % percentage point greater change from baseline in the supplemented group. Authors' conclusions: These results do not support vitamin D supplementation to improve bone density in healthy children with normal vitamin D levels, but suggest that supplementation of deficient children may be clinically useful. Further RCTs in deficient children are needed to confirm this. PLAIN LANGUAGE SUMMARY Vitamin D for improving bone density in children This summary of a Cochrane Review, presents what we know from research about the effect of vitamin D supplements on bone density in children. The review shows that in healthy children generally, vitamin D supplementation does not improve bone density at the hip, lumbar spine, forearm or in the body as a whole. Some of the evidence suggests that vitamin D supplements may improve bone density in children who have low levels of vitamin D but this is uncertain. We do not have precise information about side effects and complications but the available information suggests that vitamin D supplements are well tolerated. What is osteoporosis and what is vitamin D? Osteoporosis is a condition where bones are weak, brittle and break easily. The risk of osteoporosis and fractures (breaks) in later life depends on how much bone is built when a child and how much bone is lost when an adult. One way to prevent osteoporosis and fractures in later life is to build stronger bones when young. Vitamin D plays an important role in improving the body's absorption of calcium from food, reducing losses of calcium from the body and getting calcium deposited into to bone to improve the quantity of bone developed. Therefore it is thought that if vitamin D levels in the body are low in childhood, less bone will be developed and that improving vitamin D levels by supplements would result in more bone being developed. Bone density is a major measure of bone strength and the amount of bone mineral present at different sites and so is used to measure the effects of interventions, like vitamin D supplementation, to improve bone health.

Primary Care–Relevant Interventions to Prevent Falling in Older Adults: A Systematic Evidence Review for the U.S. Preventive Services Task Force

Falls among older adults are both prevalent and preventable. To describe the benefits and harms of interventions that could be used by primary care practitioners to prevent falling among community-dwelling older adults. The reviewers evaluated trials from a good-quality systematic review published in 2003 and searched MEDLINE, the Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and CINAHL from the end of that review's search date to February 2010 to identify additional English-language trials. Two reviewers independently screened 3423 abstracts and 638 articles to identify randomized, controlled trials (RCTs) of primary care-relevant interventions among community-dwelling older adults that reported falls or fallers as an outcome. Trials were independently critically appraised to include only good- or fair-quality trials; discrepancies were resolved by a third reviewer. One reviewer abstracted data from 61 articles into standardized evidence tables that were verified by a second reviewer. Overall, the included evidence was of fair quality. In 16 RCTs evaluating exercise or physical therapy, interventions reduced falling (risk ratio, 0.87 [95% CI, 0.81 to 0.94]). In 9 RCTs of vitamin D supplementation, interventions reduced falling (risk ratio, 0.83 [CI, 0.77 to 0.89]). In 19 trials involving multifactorial assessment and management, interventions with comprehensive management seemed to reduce falling, although overall pooled estimates were not statistically significant (risk ratio, 0.94 [CI, 0.87 to 1.02]). Limited evidence suggested that serious clinical harms were no more common for older adults in intervention groups than for those in control groups. Interventions and methods of fall ascertainment were heterogeneous. Data on potential harms of interventions were scant and often not reported. Primary care-relevant interventions exist that can reduce falling among community-dwelling older adults. Agency for Healthcare Research and Quality.

Vitamin D and the Prevention of Hypertension and Cardiovascular Diseases: A Review of the Current Evidence

Vitamin D plays an essential role in bone mineralization and calcium homeostasis. More recently, there has been growing evidence for a role of vitamin D in extraskeletal health, including beneficial effects in the cardiovascular system. Daylight exposure and vitamin D intake in many western populations are insufficient for maintaining an adequate vitamin D status. It is at present unclear whether vitamin D supplementation could improve cardiovascular health. This paper summarizes the evidence from observational studies and randomized-controlled trials on the relation of vitamin D with blood pressure (BP) and risk of cardiovascular diseases (CVDs). Epidemiological data suggest that optimal vitamin D status is important for CVD prevention, but results from different studies are conflicting and confounding cannot be ruled out. Randomized-controlled trials of vitamin D supplementation and BP have yielded inconsistent results, and trials that addressed the effect of vitamin D on CVDs are lacking. It is therefore premature to recommend supplemental vitamin D intake specifically for the prevention of hypertension or CVDs. Data from large, well-controlled clinical trials in this field with vitamin D supplements of sufficiently high doses are awaited to settle this issue.