Relation between Vitamin D and COVID-19 in Aged People: A Systematic Review

Abstract

Background: Vitamin D has diverse and extensive effects on the immune system, including activating innate immunity and reducing the overactive adaptive immune response. A systematic review was performed to identify and synthesize the best available evidence on the association between vitamin D level and risk of COVID-19, adverse outcomes and possible benefits of supplementation in aged 60 years or over. Methods: A literature search was performed in PubMed© and Scopus© for all publications from inception published before 15 March 2021. Studies reporting data from aged patients on vitamin D use and COVID-19 were included. Basic science articles, editorials and correspondence were excluded. Publication year, study design and setting, characteristics of the study population were extracted. This study is registered with PROSPERO, under the number CRD42020223993. Results: In total, 707 studies were identified, of which 11 observational studies were included in the final review. Four studies compared vitamin D-supplemented COVID-19 patients to non-supplemented patients, and seven compared patients with vitamin D deficiency to patients without deficiency. In all four studies, patients with vitamin D supplementation had better rates of primary clinical outcomes (death, the severity of the disease, oxygen therapy requirement…). In studies comparing patients with vitamin D deficiency and patients without vitamin D deficiency, those without vitamin D deficiency had better primary clinical outcomes (death rate, the severity of the disease, oxygen therapy requirement, invasive mechanical ventilation need…). Conclusion: This systematic review seems to support an association between vitamin D deficiency and the risk of COVID-19 in aged people. In addition, vitamin D deficiency appears to expose these subjects to a greater risk of adverse outcomes. Because of its simplicity of administration, and the rarity of side effects, including vitamin D in preventive strategies for certain viral diseases, it appears to be an attractive option.

Vitamin D and Exercise Are Major Determinants of Natural Killer Cell Activity, Which Is Age- and Gender-Specific

“…Thus, vitamin D insufficiency [i.e., serum 25 (OH)D level 20-29.9 ng/mL] or deficiency [serum 25(OH)D level < 20 ng/mL] are associated with increased infection susceptibility, increased cancer incidence, poor survival of cancer patients, and development of autoimmune diseases (34,36,37). For example, recent studies suggested that vitamin D insufficiency and deficiency were associated with increased susceptibility to COVID-19 and severe presentation and mortality from it (38)(39)(40). Vitamin D, having an immune modulatory function, is considered to reduce the production of pro-inflammatory cytokines, thus, reducing the severity and mortality of COVID-19 (35).…”

Previous Vitamin D Supplementation and Morbidity and Mortality Outcomes in People Hospitalised for COVID19: A Cross-Sectional Study

“…In a systematic review including 4 observational studies to assess the association between vitamin D supplementation or level with COVID-19 infection susceptibility and outcomes (clinical course, morbidity and mortality outcomes), no robust association was found between vitamin D and COVID-19 severity of symptoms or mortality (24). Another systematic review with 11 studies about vitamin D levels/supplementation and risk of COVID-19 infection, adverse outcomes and possible benefits among subjects aged 60 years or over concluded that supplementation with vitamin D during COVID-19 reduced the risks for mortality, high flow oxygen therapy needs, or ICU support (25). Nevertheless, the authors pointed out the importance of the characteristics of the supplementation regimen, with aspects that remain unresolved such as the dose, frequency of administration, and duration (25).…”

“…Another systematic review with 11 studies about vitamin D levels/supplementation and risk of COVID-19 infection, adverse outcomes and possible benefits among subjects aged 60 years or over concluded that supplementation with vitamin D during COVID-19 reduced the risks for mortality, high flow oxygen therapy needs, or ICU support (25). Nevertheless, the authors pointed out the importance of the characteristics of the supplementation regimen, with aspects that remain unresolved such as the dose, frequency of administration, and duration (25). In our sub-analysis of subjects aged 60 years or over, the composite outcome of death and/or IMV was more frequent for both groups (on vitamin D and without) than in the total study group; however, no differences were observed regarding the use of previous vitamin D. Independently of previous vitamin D intake, evidence suggests that subjects over 60 years are more prone to severe complications and longer duration of COVID-19 compared with younger persons (age 60 or younger) (26)(27)(28); this was also observed in our study.…”

“…The possible biological explanation for this effect could be the influence of genes regulating the immune system and the inflammatory response, which might modify the susceptibility to and severity of infections (34). Vitamin D deficiency is highly prevalent, especially in older adults, mainly due to the decreased synthesis in the skin or deficient dietary intake (35), and it could be easily prevented with regular supplementations (25). In our study, another important limitation is the lack of information on the levels of vitamin D among the study subjects.…”

El rol de la suplementación con vitamina D en la infección por COVID-19

“…Si bien existe consenso en la comunidad científica acerca de que no se ha establecido una clara relación causal entre los valores de vitamina D y el COVID-19 15,16 , el interés creciente en este tema se refleja en los hallazgos de nuestra estrategia de búsqueda, mediante la cual encontramos numerosas revisiones sistemáticas publicadas en los primeros meses de este año dirigidas a evaluar las infecciones por SARS-CoV-2 en relación con los niveles séricos de esta vitamina [17][18][19][20][21][22][23][24][25][26][27][28] . A pesar de que la mayoría de ellas concluye que niveles bajos de esta biomolécula podrían estar asociados con un mayor riesgo de COVID-19 o con el desarrollo de formas más severas de la enfermedad, la confianza en esta evidencia es muy baja, por provenir de estudios observacionales, con alta heterogeneidad clínica y metodológica y riesgo de sesgo de publicación significativo, por lo que no es suficiente para avalar un efecto terapéutico o preventivo de la administración de suplementos de esta vitamina.…”