The world is in the grip of the COVID-19 pandemic. Public health measures that can reduce the risk of infection and death in addition to quarantines are desperately needed. This article reviews the roles of vitamin D in reducing the risk of respiratory tract infections, knowledge about the epidemiology of influenza and COVID-19, and how vitamin D supplementation might be a useful measure to reduce risk. Through several mechanisms, vitamin D can reduce risk of infections. Those mechanisms include inducing cathelicidins and defensins that can lower viral replication rates and reducing concentrations of pro-inflammatory cytokines that produce the inflammation that injures the lining of the lungs, leading to pneumonia, as well as increasing concentrations of anti-inflammatory cytokines. Several observational studies and clinical trials reported that vitamin D supplementation reduced the risk of influenza, whereas others did not. Evidence supporting the role of vitamin D in reducing risk of COVID-19 includes that the outbreak occurred in winter, a time when 25-hydroxyvitamin D (25(OH)D) concentrations are lowest; that the number of cases in the Southern Hemisphere near the end of summer are low; that vitamin D deficiency has been found to contribute to acute respiratory distress syndrome; and that case-fatality rates increase with age and with chronic disease comorbidity, both of which are associated with lower 25(OH)D concentration. To reduce the risk of infection, it is recommended that people at risk of influenza and/or COVID-19 consider taking 10,000 IU/d of vitamin D3 for a few weeks to rapidly raise 25(OH)D concentrations, followed by 5000 IU/d. The goal should be to raise 25(OH)D concentrations above 40–60 ng/mL (100–150 nmol/L). For treatment of people who become infected with COVID-19, higher vitamin D3 doses might be useful. Randomized controlled trials and large population studies should be conducted to evaluate these recommendations.

Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths.

Immune support by micronutrients is historically based on vitamin C deficiency and supplementation in scurvy in early times. It has since been established that the complex, integrated immune system needs multiple specific micronutrients, including vitamins A, D, C, E, B6, and B12, folate, zinc, iron, copper, and selenium, which play vital, often synergistic roles at every stage of the immune response. Adequate amounts are essential to ensure the proper function of physical barriers and immune cells; however, daily micronutrient intakes necessary to support immune function may be higher than current recommended dietary allowances. Certain populations have inadequate dietary micronutrient intakes, and situations with increased requirements (e.g., infection, stress, and pollution) further decrease stores within the body. Several micronutrients may be deficient, and even marginal deficiency may impair immunity. Although contradictory data exist, available evidence indicates that supplementation with multiple micronutrients with immune-supporting roles may modulate immune function and reduce the risk of infection. Micronutrients with the strongest evidence for immune support are vitamins C and D and zinc. Better design of human clinical studies addressing dosage and combinations of micronutrients in different populations are required to substantiate the benefits of micronutrient supplementation against infection.

A Review of Micronutrients and the Immune System–Working in Harmony to Reduce the Risk of Infection

Public health practices including handwashing and vaccinations help reduce the spread and impact of infections. Nevertheless, the global burden of infection is high, and additional measures are necessary. Acute respiratory tract infections, for example, were responsible for approximately 2.38 million deaths worldwide in 2016. The role nutrition plays in supporting the immune system is well-established. A wealth of mechanistic and clinical data show that vitamins, including vitamins A, B6, B12, C, D, E, and folate; trace elements, including zinc, iron, selenium, magnesium, and copper; and the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid play important and complementary roles in supporting the immune system. Inadequate intake and status of these nutrients are widespread, leading to a decrease in resistance to infections and as a consequence an increase in disease burden. Against this background the following conclusions are made: (1) supplementation with the above micronutrients and omega-3 fatty acids is a safe, effective, and low-cost strategy to help support optimal immune function; (2) supplementation above the Recommended Dietary Allowance (RDA), but within recommended upper safety limits, for specific nutrients such as vitamins C and D is warranted; and (3) public health officials are encouraged to include nutritional strategies in their recommendations to improve public health.

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Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect against Viral Infections.

Role of vitamin D in preventing of COVID-19 infection, progression and severity.

Relevance to nursing care The evidence available regarding vitamin D on mortality has been inconclusive. Vitamin D can be obtained from sun exposure on skin, dietary intake, or supplementation as vitamin D3 or D2. Proper balance of vitamin D and calcium levels are important for healthy bones. Past studies have indicated that vitamin D supplementation prevents osteoporosis, osteomalacia, and fractures. Contradictory studies suggest that vitamin D may prevent cancer, cardiovascular disease, and affect mortality; and observational research has indicated a relationship of low vitamin D levels and risk of mortality. Evidence related to vitamin D is important for nurses working with patients with and without vitamin D insufficiency. The value of vitamin D needs clarification, and health information about risk factors, common problems with deficiency, as well as the benefits and proper use of vitamin D supplementation are needed by patients and caregivers. The purpose of this systematic review was to assess the beneficial and harmful effects of vitamin D supplementation on the prevention of mortality in healthy adults and in adults with a stable form of disease.

Vitamin D supplementation for prevention of mortality in adults

Effect of vitamin D supplementation on non-skeletal disorders: a systematic review of meta-analyses and randomised trials

Studies on active and passive tobacco smoking and breast cancer have found inconsistent results. A meta-analysis of observational studies on tobacco smoking and breast cancer occurrence was conducted based on systematic searches for studies with retrospective (case-control) and prospective (cohort) designs. Eligible studies were identified, and relative risk measurements were extracted for active and passive tobacco exposures. Random-effects meta-analyses were used to compute summary relative risks (SRR). Heterogeneity of results between studies was evaluated using the (I (2)) statistics. For ever active smoking, in 27 prospective studies, the SRR for breast cancer was 1.10 (95 % CI [1.09-1.12]) with no heterogeneity (I (2) = 0 %). In 44 retrospective studies, the SRR was 1.08 (95 % CI [1.02-1.14]) with high heterogeneity (I (2) = 59 %). SRRs for current active smoking were 1.13 (95 % CI [1.09-1.17]) in 27 prospective studies and 1.08 (95 % CI [0.97-1.20]) in 22 retrospective studies. The results were stable across different subgroup analyses, notably pre/post-menopause, alcohol consumption adjustments, including/excluding passive smokers from the referent group. For ever passive smoking, in 11 prospective studies, the SRR for breast cancer was 1.07 (95 % CI [1.02-1.13]) with no heterogeneity (I (2) = 1 %). In 20 retrospective studies, the SRR was 1.30 (95 % CI [1.10-1.54]) with high heterogeneity (I (2) = 74 %). Too few prospective studies were available for meaningful subgroup analyses. There is consistent evidence for a moderate increase in the risk of breast cancer in women who smoke tobacco. The evidence for a moderate increase in risk with passive smoking is more substantial than a few years ago.

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Active and passive smoking and risk of breast cancer: a meta-analysis

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Global burden of pancreas cancer: regional disparities in incidence, mortality and survival

ABSTRACT Objectives: Of the possible causes of cancer, nutritional factors are supposed to play a major role in preventable cancers. Regarding prostate cancer, nutritional data remain contradictory. This article aims to review current evidence on the relation between nutrition and prostate cancer. Material and methods: A systematic literature search for meta-analyses, systematic reviews, and pooled analyses was conducted in the PubMed database from its inception to September 2019. Eligible studies had to assess the association between nutrition and risk of prostate cancer. Results: Generally, no evidence was found for an association between most food items or groups, including fruit, vegetables, meat, tea, coffee, and risk of prostate cancer. There was an inconsistent and weak positive association between milk and dairy foods and prostate cancer. Carbohydrates, vitamins, and minerals were not associated with prostate cancer. Furthermore, no association was found with dietary patterns such as vegetarian or pesco-vegetarian, but increased adherence to a Mediterranean diet seemed to have a protective effect. In general, large heterogeneity between studies was observed. Studies included in meta-analyses were mostly observational, and therefore prone to several inherent biases. Conclusions: The evidence on any potential association between diet and prostate cancer is weak. The reductionist approach considering individual nutritional factors is not suitable, and conducting more observational studies or small randomised trials evaluating the impact of individual nutritional factors on prostate cancer will not bring further answers. Large, well-designed, randomised, controlled trials are mandatory in order to clarify the relationship between nutrition and prostate cancer.

https://www.termedia.pl/Journal/-100/pdf-39562-10?filename=Nutrition and prostate.pdf

Nutrition and prostate cancer: review of the evidence

https://www.termedia.pl/Journal/-100/pdf-39533-10?filename=Global burden.pdf

Alina Macacu

Papers

Effect of vitamin D supplementation on non-skeletal disorders: a systematic review of meta-analyses and randomised trials

Active and passive smoking and risk of breast cancer: a meta-analysis

Global burden of pancreas cancer: regional disparities in incidence, mortality and survival

Nutrition and prostate cancer: review of the evidence

Global burden of diabetes: regional disparities in prevalence, incidence, and mortality