key: cord-0720500-wmdcxmq2
authors: Jayawardena, Ranil; Sooriyaarachchi, Piumika; Chourdakis, Michail; Jeewandara, Chandima; Ranasinghe, Priyanga
title: Enhancing immunity in viral infections, with special emphasis on COVID-19: A review
date: 2020-04-16
journal: Diabetes Metab Syndr
DOI: 10.1016/j.dsx.2020.04.015
sha: 5d2782186cd6fb674efc3ca900537223d2a50cab
doc_id: 720500
cord_uid: wmdcxmq2

Abstract Background and aims Balanced nutrition which can help in maintaining immunity is essential for prevention and management of viral infections. While data regarding nutrition in coronavirus infection (COVID-19) are not available, in this review, we aimed to evaluated evidence from previous clinical trials that evaluated nutrition-based interventions for viral diseases (with special emphasis on respiratory infections), and summaries our observations. Methods A systematic search strategy was employed using keywords to search the literature in 3 key medical databases: PubMed®, Web of Science® and SciVerse Scopus®. Studies were considered eligible if they were controlled trials in humans, measuring immunological parameters, on viral and respiratory infections. Clinical trials on vitamins, minerals, nutraceuticals and probiotics were included. Results total of 640 records were identified initially and 22 studies were included from other sources. After excluding duplicates and articles that did not meet the inclusion criteria, 43 studies were obtained (vitamins: 13; minerals: 8; nutraceuticals: 18 and probiotics: 4). Among vitamins, A and D showed a potential benefit, especially in deficient populations. Among trace elements, selenium and zinc have also shown favourable immune-modulatory effects in viral respiratory infections. Several nutraceuticals and probiotics may have some role in enhancing immune functions. Micronutrients may be beneficial in nutritionally depleted elderly population. Conclusions We summaries possible benefits of some vitamins, trace elements, nutraceuticals and and probiotics. Nutrition principles based on these data could be useful in possible prevention and management of COVID-19

Background and Aims 27 Balanced nutrition which can help in maintaining immunity is essential for prevention and 28 management of viral infections. While data regarding nutrition in coronavirus infection 29 (COVID-19) are not available, in this review, we aimed to evaluated evidence from 30 previous clinical trials that evaluated nutrition-based interventions for viral diseases (with 31 special emphasis on respiratory infections), and summaries our observations. 140 A summary of RCTs on vitamins and multi-nutrient supplements that are discussed below 141 is presented in Table 1 . 142 

Vitamin A is a fat-soluble vitamin, which is crucial for maintaining vision, promoting 144 growth and development, and protecting epithelium and mucosal integrity in the body [15] . 145 It is known to play an important role in enhancing immune function, and having a 146 regulatory function in both cellular and humoral immune responses [15] . Vitamin A 147 supplementation to infants has shown the potential to improve antibody response after meta-analysis on the role of vitamin C for preventing and treating the common cold, did 205 not find any conclusive evidence to indicate that there is benefit of using vitamin C mega-206 dose prophylaxis in the community to reduce the incidence of common cold, which is most 207 often caused by viral infections [32] . 

The best of our knowledge, this is the first systematic review reporting nutritional 327 interventions to enhance immunity in viral infections taking into consideration the current 328 epidemic of COVID-19. This comprehensive review reports evidence on several vitamins, 329 particularly A, D and E, as well as a few trace elements, such as Zinc and Selenium. In addition to micronutrients, obesity has long been associated with higher risks of 393 Recommendations are summarized in Table 5 . In addition to basic hygienic Clinical: Correction of specific nutrient deficiencies was observed after 6 months and was maintained for the first year, during which there was no effect of any treatment on delayedtype hypersensitivity skin response. Number of patients without respiratory tract infections during the study was higher in groups that received trace CG: Placebo group (calcium phosphate and microcrystalline cellulose) elements.

Immunological: Antibody titers after influenza vaccine were higher in groups that received trace elements alone or associated with vitamins, whereas the vitamin group had significantly lower antibody titers. in blood before flu vaccination and a dose-dependent increase in T cell proliferation, IL-8 and IL-10 secretion after in vivo flu challenge. Positive effects were contrasted by lower granzyme B content of CD8 cells. Selenium-onions also enhanced T cell proliferation after vaccination, IFNγ and IL-8 secretion, granzyme and perforin content of CD8 cells but inhibited TNF-a synthesis. Onion on its own reduced the number of NK cells in blood. Mucosal flu-specific antibody responses were unaffected by Selenium supplementation. Immunological: Selenium supplementation increased lymphocyte phospholipid and cytosolic glutathione peroxidase activity. Selenium supplements augmented cellular immune response through an increased production of interferon and other cytokines, an earlier peak T cell proliferation, an increase in T helper cells and more rapid clearance of poliovirus. Humoral immune responses were unaffected. Immunological: Ceruloplasmin activity, benzylamine oxidase, and super-oxide dismutase were significantly higher at the end of the second period than at the end of the first. Polymorphonuclear cell count, the percentage of white blood cells, lymphocyte count, and IL2R were affected by copper supplementation. Antibody titre for the Beijing strain of influenza virus was significantly lower in IG after immunization than in CG. * Group allocation not mentioned; C -Controlled; CD -Cluster of differentiation; CG -Control group; DTH -Delayed type hypersensitivity; IFN -Interferon; IG -Intervention group; IL -Interleukin; MRU -Metabolic research unit; NK -Natural killer cells; NA -Not applicable; NM -Not mentioned; PC -Placebo controlled; R -Randomized; TB -Triple blind; SEP -selenoproteins; TNF -Tumour necrosis factor No significant between-group differences were found in total symptom score among three groups.

Immunological: Viral persistent rates and serum cytokine levels (IFN-a, IL6, IL-8, IL-10, and TNF-a) during the study period showed no differences among 3 groups. Clinical: Most cold episodes occurred in the CG; however, the difference was not significant. CG participants had a significantly longer duration of cold episode days and the average symptom score over these days was also significantly higher. A significant reduction of cold duration and severity in air travellers with elderberry capsule.

Immunological: NA 

Energy expenditure in HIV infection. The American journal of 788 clinical nutrition

Diabetes patients with COVID-19 need better blood glucose 790 management in Wuhan

Clinical considerations for patients with diabetes in times of 792

COVID-19 epidemic

incidence of common cold infections, but significantly shortened duration of episodes by almost 2 days and reduced the severity of symptoms.Immunological: IG had a larger increase in cytotoxic T plus T suppressor cell counts and in T helper cell counts.BB536 -Bifidobacterium longum 536; CG -Control group; DB -Double blind; IG -Interventional group; IgA -Immunoglobulin A; NA -Not applicable; NK -Natural killer cells; PC -Placebo controlled; R -Randomized;

Not relevant since this is a review