BACKGROUND & OBJECTIVE: It has been suggested that prenatal vitamin D plays a role in the development of childhood asthma and wheeze. Several systematic reviews have been conducted, but the results are inconsistent, and the methodological quality has not been studied. Therefore, the objective of this umbrella review was to assess the internal validity of the evidence base and the evidence for an association between prenatal vitamin D and asthma or wheezing in the offspring.
METHODS: We searched the electronic databases Embase, PubMed, and Cochrane Library for studies on prenatal vitamin D using search words such as vitamin D, 25-hydroxyvitamin D, calcidiol, fetal, and neonatal. The search was conducted in June 2020, and the databases were searched from their date of establishment. We included systematic reviews and/or meta-analyses of experimental and observational studies assessing the association between prenatal vitamin D or asthma and wheeze. We excluded narrative reviews, commentaries, and other umbrella reviews. The methodological quality of systematic reviews was assessed using AMSTAR 2 tool. PROSPERO reg. no. CRD42020151329.
RESULTS: We identified 22 eligible systematic reviews (17 on asthma and 20 on wheeze). Using the AMSTAR 2 quality assessment tool, the methodological quality was rated as critically low in 21 out of 22 systematic reviews, suggesting that previous reviews and meta-analyses did not provide accurate and comprehensive summaries of the included studies and that conclusions reached were potentially flawed. The majority of the included reviews reported that prenatal vitamin D reduces the risk of wheeze in the offspring.
CONCLUSION: Prior to informing public guidelines, high-quality systematic reviews of the current evidence are greatly warranted.
INTRODUCCIÓN: Las vitaminas son micronutrientes indispensables para el ser humano, ya que participan en diversas funcionas normales. Asimismo, su déficit puede causar serios problemas de salud. Con el abrupto advenimiento del COVID-19 y su rápido desarrollo hasta convertirse en pandemia, se han venido ofertando el uso sin prescripción médica de suplementos vitamínicos (compuestos únicos [como vitamina C] o en multivitamínicos) para prevenir o tratar el COVID-19, a pesar de que, a la fecha, no está aprobado su uso para la prevención o tratamiento del COVID-19 ni de ninguna outra infección del tracto respiratorio. Uno de los principales argumentos para la venta de estos suplementos se basa en que las vitaminas tienen un rol "fortalecedor" del sistema imnume por lo que tendrían efectos en la prevención o tratamiento de diversos problemas de salud, tales como las infecciones del tracto respiratorio. Sin embargo, la existencia de evidencia científica de un rol inmunomodulador de las vitaminas no implica necesariamente que estas deban ser eficaces o efectivas para prevenir o tratar el COVID19 o si quiera alguna otra infección del tracto respiratorio. Con la finalidad de brindar a las personas una información confiable acerca del uso de suplementos vitamínicos, la Seguridad Social, EsSalud, ha formado un Comité de Emergencias que tiene como evaluar la evidencia disponible acerca de la efectividad de los suplementos vitamínicos en la prevención o tratamiento de COVID-19. En tal sentido, el objetivo principal de esta revisión rápida es generar evidencia a partir de la literatura científica publicada que evalúe la efectividad de los suplementos vitamínicos en COVID-19. Previendo que la literatura directamente relacionada con COVID-19 sería escasa, ampliamos la pregunta de investigación para explorar la existencia de evidencia analógica, evaluando así también la eficacia/efectividad de los suplementos vitamínicos en la prevención o tratamiento de otras infecciones del tracto respiratorio (tales como , resfriado común, influenza, incluyendo neumonía). Así, esta revisón también nos permitió evaluar qué tan razonables son los argumentos utilizados para recomendar el uso de estos suplementos vitamínicos en infecciones del tracto respiratorio en general. MÉTODOS: Relacionados con el tema a tratar: uso de suplementos vitamínicos para la prevención o el tratamiento de COVID-19, infecciones por otros coronavirus o infecciones del tracto respiratorio (excluyendo tuberculosis). Para COVID-19 o infecciones por otros coronavirus: Umbrella reviews, revisiones sistemáticas, ECAs, estudios observacionales (cohortes, casocontrol o transversal). § Para infecciones del tracto respiratorio (excluyendo tuberculosis): Umbrella reviews, revisiones sistemáticas de ensayos clínicos aleatorizados controlados. RESULTADOS: De acuerdo con nuestra estrategia de búsqueda identificamos 650 estudios. Adicionalmente, hallamos 1 registros a través de otras fuentes. Un revisor (PSB) evaluó la elegibilidad de los estudios según títulos y resúmenes aplicando los objetivos de la presente revisión y la pregunta de investigación (PICO). Las referencias que cumplieron con los criterios de búsqueda fueron exportadas al software de manejo de referencias Zoter. Luego de la lectura por títulos y resúmenes se excluyeron 639 artículos por no abordar los criterios de nuestra pregunta PICO: población, tipo intervención, comparador, desenlace o tipo de estudio; quedando 12 artículos para lectura a texto completo. Luego de la lectura a texto completo llevada a cabo por PSB se incluyeron todos los artículos para la realización de este reporte de evidencia. De estos 12 artículos, nueve fueron revisiones sistemáticas y tres fueron revisiones umbrella que respondieran a la pregunta PICO. Todas las RS incluyeron ECA y todas las revisiones umbrela sincluyeron solamente revisiones de ECA . Ninguna RS o revisión umbrela evalúo la eficacia/efectividad de algún suplemento vitamínico para prevenir o tratar COVID-19 nin ninguna otra infección por coronavirus. Tres RS y dos revisiones umbrela evaluaron el efecto de la vitamina C para prevenir o tratar infecciones del tracto respiratoria, tales como resfrío común, influenza o neumonía; mientras que cinco RS y una revisión umbrela evaluaron el efecto de la vitamina D y solo una el efecto de la vitamina A. No encontramos ninguna RS ni revisión umbrela que evaluara la eficacia/efectivida de las vitaminas E, K, B6, B12, U, ácido fólico, complejo B, riboflvina o algún otor compuesto multivitamínico. CONCLUSIONES: Hasta la fecha de esta revisión, no existen estudios primarios que evalúen directamente la eficacia/efectividad de algún suplemento vitamínico (mono o multivitamínico) para la prevención o tratamiento de COVID-19. La abudante literatura existente acerca de los suplementos de vitamina C indica que su consumo de manera continua no previene el resfrío común y que su impacto sobre la duración de los síntomas es nulo o insignificante en niños y adultos. Es muy poco probable que estas conclusiones cambien si aparecen más estudios similares bien diseñados, por lo que tampoco se justifica su uso para prevenir o tratar infecciones del tracto respiratorio, tal y como viene siendo promocionado. La evidencia acerca de la vitamina D es limitada y no concluyente, existiendo evidencia contradictoria que sugiere la existencia de un pequeño efecto de esta en la prevención de infecciones del tracto respiratorio en algunso estudios, mientras que otros estudios fallan en corroborar estos hallazgos. La evidencia acerca de la vitamina A es muy limitada, existiendo incluso evidencia de un ligero incremento del riesgo de contraer infección respiratoria en quienes consumen vitamina A versus placebo.
Brief overview: Current evidence suggests vitamin D replacement may reduce risk for acute respiratory tract infections (ARTI) in people with deficiency or insufficiency, although the effects of supplementation on incidence and severity of ARTI in the general population remain unknown. Oral vitamin D supplemzentation taken at routine doses appears to be generally safe and well tolerated. Verdict: Current experimental evidence remains inconclusive regarding the effects of vitamin D supplementation in the general population for the prevention and treatment of acute respiratory tract infections (ARTI). There is also insufficient evidence to draw conclusions regarding the impact of vitamin D supplementation on the severity or duration of ARTI, nor on outcomes related to lung injury or hospitalization from ARTI. Based on this rapid review, sources of significant heterogeneity in published clinical trials include: differences study populations, inconsistent assessment of serum status at baseline, dosing variability, varying routes of administration, and/or inconsistent definitions of outcome measures. Experimental evidence and observations in large cohorts are generally consistent that vitamin D deficiency (<50 nmol/L [<20 ng/mL]) and insufficiency (<75 nmol/L [<30 ng/mL]) of serum 25-hydroxycholecalciferol (25-OHD) concentration is associated with increased risk of ARTI, and supplementation for those with deficiency/insufficiency may lead to clinically meaningful reductions in the incidence of ARTI. In this rapid review, vitamin D was primarily administered as oral supplementation, and findings suggested significant differences in daily oral dosing compared to periodic bolus dosing. Based on the available experimental evidence, vitamin D supplementation appears to have a high margin of safety with very few adverse events reported in children or adults from a variety of dosing strategies. Future clinical trials on vitamin D should consider the sources of heterogeneity in the existing experimental research and design trials that account for baseline status, evaluate the potential for prevention and treatment in at risk populations, standardize dosing strategies, assess product quality, assess outcomes according to gold standard definitions/diagnostic methods, and delineate viral ARTI from other causes when possible. The available mechanistic evidence related to immunological requirements for adequate vitamin D, the availability of observational and experimental evidence suggestive of clinically meaningful benefits (especially in deficient/insufficient participants), and the high margin of safety, should make vitamin D a high priority for additional clinical research during the current COVID-19 pandemic.
There are limited proven therapeutic options for the prevention and treatment of COVID-19. The role of vitamin and mineral supplementation or "immunonutrition" has previously been explored in a number of clinical trials in intensive care settings, and there are several hypotheses to support their routine use. The aim of this narrative review was to investigate whether vitamin supplementation is beneficial in COVID-19. A systematic search strategy with a narrative literature summary was designed, using the Medline, EMBASE, Cochrane Trials Register, WHO International Clinical Trial Registry, and Nexis media databases. The immune-mediating, antioxidant and antimicrobial roles of vitamins A to E were explored and their potential role in the fight against COVID-19 was evaluated. The major topics extracted for narrative synthesis were physiological and immunological roles of each vitamin, their role in respiratory infections, acute respiratory distress syndrome (ARDS), and COVID-19. Vitamins A to E highlighted potentially beneficial roles in the fight against COVID-19 via antioxidant effects, immunomodulation, enhancing natural barriers, and local paracrine signaling. Level 1 and 2 evidence supports the use of thiamine, vitamin C, and vitamin D in COVID-like respiratory diseases, ARDS, and sepsis. Although there are currently no published clinical trials due to the novelty of SARS-CoV-2 infection, there is pathophysiologic rationale for exploring the use of vitamins in this global pandemic, supported by early anecdotal reports from international groups. The final outcomes of ongoing trials of vitamin supplementation are awaited with interest.
It has been suggested that prenatal vitamin D plays a role in the development of childhood asthma and wheeze. Several systematic reviews have been conducted, but the results are inconsistent, and the methodological quality has not been studied. Therefore, the objective of this umbrella review was to assess the internal validity of the evidence base and the evidence for an association between prenatal vitamin D and asthma or wheezing in the offspring.
METHODS:
We searched the electronic databases Embase, PubMed, and Cochrane Library for studies on prenatal vitamin D using search words such as vitamin D, 25-hydroxyvitamin D, calcidiol, fetal, and neonatal. The search was conducted in June 2020, and the databases were searched from their date of establishment. We included systematic reviews and/or meta-analyses of experimental and observational studies assessing the association between prenatal vitamin D or asthma and wheeze. We excluded narrative reviews, commentaries, and other umbrella reviews. The methodological quality of systematic reviews was assessed using AMSTAR 2 tool. PROSPERO reg. no. CRD42020151329.
RESULTS:
We identified 22 eligible systematic reviews (17 on asthma and 20 on wheeze). Using the AMSTAR 2 quality assessment tool, the methodological quality was rated as critically low in 21 out of 22 systematic reviews, suggesting that previous reviews and meta-analyses did not provide accurate and comprehensive summaries of the included studies and that conclusions reached were potentially flawed. The majority of the included reviews reported that prenatal vitamin D reduces the risk of wheeze in the offspring.
CONCLUSION:
Prior to informing public guidelines, high-quality systematic reviews of the current evidence are greatly warranted.
