Can Vitamin D3 Help Prevent Infections?

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Can Vitamin D3 Help Prevent Infections?

You’re feeling slightly ‘under the weather’. The situation is crummy but you assume it will pass…until things take a turn for the worse. What you thought was a minor hiccup in your day is actually a full-blown cold, leaving you wondering how you might prevent such an unwelcome turn of events in the future.

Acute respiratory tract infections (ARTIs)—which are often caused by bacteria or viruses (1)—are the source of roughly five million deaths around the globe each year (2).

They are infections that get in the way of normal breathing (3), and come with symptoms congestion, runny nose, cough, sore throat, muscle aches, and fatigue (3).

The common cold (3), ear infections, bronchitis, tonsillitis (4), and pneumonia (2) all fall under this umbrella.

When it comes to colds and other similar illnesses, vitamin C supplementation has generally been the ‘hot’ topic of conversation. But…while we were all talking about vitamin C, another supplement was thrown into the mix.

Enter our good ol’ friend vitamin D, a vitamin classically known for building and maintaining strong bones (5). It turns out that this superpower vitamin also protects against germs that affect the respiratory system (6;7;8;9).

The two main forms of vitamin D are vitamin D2 and vitamin D3. Vitamin D2 is not made naturally, but is found in foods such as egg yolks, mushrooms, and fortified milk and yogurt (10). On the other hand, vitamin D3 is made in the body after exposure to the sun (10), and is also found in foods such as fatty fish (5). Both forms of vitamin D can also be taken as supplements (5;6;10).

Research has found that people with low levels of vitamin D may be more ly to get ARTIs (6;11). So, the next logical question is…can vitamin D supplements help prevent them?

What the research tells us

A recent systematic review looked at whether taking vitamin D supplements reduces the risk of ARTIs. The potential benefits were studied in people of all ages, and in both healthy individuals, as well as those with respiratory conditions asthma or chronic obstructive pulmonary disease (COPD).

In most cases, vitamin D was taken by mouth as vitamin D3 pills for seven weeks to one-and-a-half years. Supplements were consumed at lower doses (generally 0.02 to 0.05 mg) daily or weekly, or higher doses (generally 2.

4 to 3 mg) every one to three months, or through a combined effort of frequent low-dose and infrequent high-dose schedules.

The results were generally positive! The review found that vitamin D3 supplements did, in fact, lower the risk of developing ARTIs, with no serious side effects observed. The greatest benefit was seen with daily or weekly supplementation, especially in people who had low vitamin D levels to begin with.

Interestingly, people who received one or more large doses of vitamin D (e.g. once, monthly, or every two months), in addition to their daily regimen, did not experience these benefits.

While vitamin D3 reduced the risk of developing an ARTI, it had no effect on the risk of hospitalization or emergency department visits due to ARTIs (6).

All in all, it’s important to remember that while vitamin D can help ward off respiratory infections in some people, always make sure to discuss taking supplements with your healthcare provider—because supplements may not always be safe for everyone.


Can Vitamin D3 Help Prevent Infections?

Can Vitamin D3 Help Prevent Infections?

Vitamin D, the “sunshine vitamin,” works to maintain healthy immune function and general well-being. Research reveals it may also help prevent infections, especially in people who are deficient. Read on to find out what the latest science has to say about its potential to strengthen the immune response.

Vitamin D & Immunity Snapshot

  • Vitamin D maintains immune balance
  • Deficiency increases the risk of bacterial and respiratory infections
  • Supplementation may strengthen the immune response in people who are deficient
  • Limited evidence suggests supplementation may improve immunity in people with HIV

The body naturally makes vitamin D when exposed to sunlight. Getting regular, moderate sun exposure is a safe way to maintain normal vitamin D levels during the summer months.

Vitamin D is also found in certain foods, such as fatty fish salmon and sardines. Additionally, many vitamin D supplements are available on the market.

Taken at the recommended doses, vitamin D supplements are considered safe. However, taking too much can be harmful. Vitamin D supplements may also interact with prescription medications. Remember to talk to your doctor before supplementing.

Does Vitamin D Reduce the Risk of Tuberculosis?

There is insufficient evidence to determine if vitamin D supplementation is effective and safe and safe in people with tuberculosis.

Patients with low vitamin D levels have a higher risk of active tuberculosis [1, 2, 3].

Extreme vitamin D deficiency is associated with a 5-fold increased risk for progression to tuberculosis among healthy individuals who come in contact with tuberculosis [4, 5].

Blood levels of this vitamin are lower in tuberculosis patients comparing to healthy individuals [6].

Vitamin D supplementation may prevent tuberculosis, reduce infectivity and shorten the duration of disease and treatment [3, 7].

Vitamin D supplementation enhances immunity to mycobacteria [8, 9].

Vitamin D May Reduce the Risk of Respiratory Infections

Some clinical evidence suggests that vitamin D help prevent respiratory infections.

Lower levels of vitamin D are related to increased risk of respiratory infections [10].

Studies showed a decrease in respiratory tract infections in children taking 600 to 700 IU/d vitamin D supplementation [11].

Supplementation with 1,200 IU/day prevents against the flu (influenza A) in schoolchildren between December and March [12].

Supplementation with this vitamin (at 300 IU daily) significantly reduced the risk of acute respiratory infections by 50% among Mongolian children with vitamin D deficiency in winter [13].

However, a monthly dose of 100,000 IU of vitamin D in healthy adults did not significantly reduce the incidence or severity of upper respiratory tract infections [14].

Is Vitamin D Beneficial for People with HIV?

Vitamin D deficiency is common among people infected with human immunodeficiency virus (HIV).

It is associated with an increased risk of HIV disease severity and death [15, 16, 17].

HIV-infected patients with abnormally low vitamin D levels had shorter survival than other HIV-infected subjects [18].

100,000 IU of vitamin D supplementation every 2 months is safe and improves vitamin D status [16, 19].

This vitamin improves HIV-associated immunity.

High doses of vitamin D supplementation decreases virus production and increases white blood cells [20].

Further Reading

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New evidence that vitamin D prevents respiratory infections

Can Vitamin D3 Help Prevent Infections?

A large-scale meta-analysis using more than 10,000 participants concludes that vitamin D supplementation may help to prevent a major cause of global death – acute respiratory tract infections.

Share on PinterestCould vitamin D supplementation prevent acute respiratory tract infections?

Acute respiratory tract infections are responsible for 10 percent of ambulance and emergency room visits in the United States.

Including anything from the common cold to pneumonia and bronchitis, they were the cause of an estimated 2.65 million deaths globally in 2013.

Respiratory tract infections have a wide array of risk factors, including overcrowding, a damp living environment, air pollution, and parental smoking.

A number of observational studies have also reported a nutritional risk factor – vitamin D deficiency. Some researchers have concluded that vitamin D has the ability to trigger an immune response to certain viruses and bacteria.

However, the links between respiratory tract infections and vitamin D supplementation have remained controversial; some studies support the theory while others are inconclusive. To date, five meta-analyses have been conducted on existing data. Two of these reported significant positive effects, and three found no significant effect.

In an attempt to put this question to bed, the largest meta-analysis to date was published this week in the BMJ.

The analysis, carried out by an international group of researchers, is the first to use individual participant data (IPD), rather than the aggregate methodology that was used in earlier meta-analyses.

In this way, changes measured at different points in time within each participant of each trial can be accounted for, rather than taking a summary (aggregate) of the data.

IPD is considered the “gold standard” of systematic review.

The team used data from 25 randomized controlled trials investigating vitamin D supplementation. In total, data from 11,321 participants were analyzed.

After adjusting for potentially confounding variables, such as sex, age, and study duration, they found that vitamin D supplementation produced a 12 percent reduction in the proportion of individuals experiencing at least one acute respiratory tract infection.

In simple terms, if 33 people took vitamin D supplements, one acute respiratory tract infection would be prevented. If these results are confirmed, vitamin D supplementation could potentially prevent millions of respiratory infections each year.

When the team drilled further into the data, they found that the positive effect was more pronounced in participants who took daily or weekly vitamin D without additional large doses. The effect was also stronger for individuals with more severe vitamin D deficiencies – only 1 in 4 people in this group would need to take vitamin D regularly to prevent one acute respiratory tract infection.

The authors concluded that:

“Our results add to the body of evidence supporting the introduction of public health measures such as food fortification to improve vitamin D status, particularly in settings where profound vitamin D deficiency is common.”

The team also concluded that vitamin D was safe to consume as a supplement; side effects were rare.

Although the thorough statistical methodology and large group of participants give the findings a degree of strength, there are limitations and some researchers remain unconvinced of the effect.

In an editorial published in the same journal, Mark Bolland from the University of Auckland in New Zealand and Alison Avenell from the University of Aberdeen in the United Kingdom, write that the results are “heterogeneous and not sufficiently applicable to the general population. We think that they should be viewed as hypothesis-generating only, requiring confirmation in well-designed adequately powered randomized controlled trials.”

The editorial also states that:

“Current evidence does not support the use of vitamin D supplementation to prevent disease, except for those at high risk of osteomalacia (weak bones and muscles due to low blood vitamin D levels, currently defined as less than 25 nanomoles per liter).”

Although the jury remains out, the recent findings have added fuel to the fire. If further trials back up the hypothesis, vitamin D supplementation could provide a cost-effective way of reducing the number of acute respiratory infections on a global basis.

Learn why cancer risk falls with increased levels of vitamin D.



Can Vitamin D3 Help Prevent Infections?

1. Khajavi A, Amirhakimi GH. The rachitic lung: pulmonary findings in 30 infants and children with malnutritional rickets. Clin Pediatr (Phila) 1977;16:36–38. [PubMed] [Google Scholar]

2. Martineau AR, Honecker FU, Wilkinson RJ, Griffiths CJ. Vitamin D in the treatment of pulmonary tuberculosis. J Steroid Biochem Mol Biol. 2007;103:793–798. [PubMed] [Google Scholar]

3. Danai PA, Sinha S, Moss M, Haber MJ, Martin GS. Seasonal variation in the epidemiology of sepsis. Crit Care Med. 2007;35:410–415. [PubMed] [Google Scholar]

4. Grant WB. Variations in vitamin D production could possibly explain the seasonality of childhood respiratory infections in Hawaii. Pediatr Infect Dis J. 2008;27:853. [PubMed] [Google Scholar]

5. Cannell JJ, Vieth R, Umhau JC, et al. Epidemic influenza and vitamin D. Epidemiol Infect. 2006;134:1129–1140. [PMC free article] [PubMed] [Google Scholar]

6. Bhalla AK, Amento EP, Clemens TL, Holick MF, Krane SM. Specific high-affinity receptors for 1,25-dihydroxyvitamin D3 in human peripheral blood mononuclear cells: presence in monocytes and induction in T lymphocytes following activation. J Clin Endocrinol Metab. 1983;57:1308–1310. [PubMed] [Google Scholar]

7. Stumpf WE, Sar M, Reid FA, Tanaka Y, DeLuca HF. Target cells for 1,25-dihydroxyvitamin D3 in intestinal tract, stomach, kidney, skin, pituitary, and parathyroid. Science. 1979;206:1188–1190. [PubMed] [Google Scholar]

8. Cantorna MT, Mahon BD. Mounting evidence for vitamin D as an environmental factor affecting autoimmune disease prevalence. Exp Biol Med (Maywood) 2004;229:1136–1142. [PubMed] [Google Scholar]

9. Wactawski-Wende J, Kotchen JM, Anderson GL, et al. (Women’s Health Initiative Investigators) Calcium plus vitamin D supplementation and the risk of colorectal cancer. N Engl J Med. 2006;354:684–696. [published correction appears in N Engl J Med.2006;354:1102] [PubMed] [Google Scholar]

10. Flanagan JN, Young MV, Persons KS, et al. Vitamin D metabolism in human prostate cells: implications for prostate cancer chemoprevention by vitamin D. Anticancer Res. 2006;26:2567–2572. [PubMed] [Google Scholar]

11. Liu PT, Stenger S, Li H, et al. Toll- receptor triggering of a vitamin D-mediated human antimicrobial response. Science. 2006;311:1770–1773. [PubMed] [Google Scholar]

12. Rook GA, Steele J, Fraher L, et al. Vitamin D3, gamma interferon, and control of proliferation of Mycobacterium tuberculosis by human monocytes. Immunology. 1986;57:159–163. [PMC free article] [PubMed] [Google Scholar]

13. Crowle AJ, Ross EJ, May MH. Inhibition by 1,25(OH)2-vitamin D3 of the multiplication of virulent tubercle bacilli in cultured human macrophages. Infect Immun. 1987;55:2945–2950. [PMC free article] [PubMed] [Google Scholar]

14. Ramanathan B, Davis EG, Ross CR, Blecha F. Cathelicidins: microbicidal activity, mechanisms of action, and roles in innate immunity. Microbes Infect. 2002;4:361–372. [PubMed] [Google Scholar]

15. Wang TT, Nestel FP, Bourdeau V, et al. Cutting edge: 1,25-dihydroxyvitamin D3 is a direct inducer of antimicrobial peptide gene expression. J Immun. 2004;173:2909–2912. [published correction appears in J Immunol. 2004;173:following 6489] [PubMed] [Google Scholar]

16. Wehkamp J, Schauber J, Stange EF. Defensins and cathelicidins in gastrointestinal infections. Curr Opin Gastroenterol. 2007;23:32–38. [PubMed] [Google Scholar]

17. Sly LM, Lopez M, Nauseef WM, Reiner NE. 1alpha,25-Dihydroxyvitamin D3-induced monocyte antimycobacterial activity is regulated by phosphatidylinositol 3-kinase and mediated by the NADPH-dependent phagocyte oxidase. J Biol Chem. 2001;276:35482–35493. [PubMed] [Google Scholar]

18. Tachi Y, Shimpuku H, Nosaka Y, et al. Vitamin D receptor gene polymorphism is associated with chronic periodontitis. Life Sci. 2003;73:3313–3321. [PubMed] [Google Scholar]

19. Malik MH, Jury F, Bayat A, Ollier WE, Kay PR. Genetic susceptibility to total hip arthroplasty failure: a preliminary study on the influence of matrix metalloproteinase 1, interleukin 6 polymorphisms and vitamin D receptor. Ann Rheum Dis. 2007;66:1116–1120. [PMC free article] [PubMed] [Google Scholar]

20. Horgan J. Space invaders: Extra! Extra! Flu linked to sunspots! Sci Am. 1990;262:26. 30. [PubMed] [Google Scholar]

21. Reichert TA, Simonsen L, Sharma A, Pardo SA, Fedson DS, Miller MA. Influenza and the winter increase in mortality in the United States, 1959–1999. Am J Epidemiol. 2004;160:492–502. [PubMed] [Google Scholar]

22. Kobasa D, Takada A, Shinya K, et al. Enhanced virulence of influenza A viruses with the haemagglutinin of the 1918 pandemic virus. Nature. 2004;431:703–707. [PubMed] [Google Scholar]

23. Cheung CY, Poon LL, Lau AS, et al. Induction of proinflammatory cytokines in human macrophages by influenza A (H5N1) viruses: a mechanism for the unusual severity of human disease? Lancet. 2002;360:1831–1837. [PubMed] [Google Scholar]

24. Cantorna MT, Yu S, Bruce D. The paradoxical effects of vitamin D on type 1 mediated immunity. Mol Aspects Med. 2008;29:369–375. [PMC free article] [PubMed] [Google Scholar]

25. Gropp R, Frye M, Wagner TO, Bargon J. Epithelial defensins impair adenoviral infection: implication for adenovirus-mediated gene therapy. Hum Gene Ther. 1999;10:957–964. [PubMed] [Google Scholar]

26. Beisswenger C, Bals R. Antimicrobial peptides in lung inflammation. Chem Immunol Allergy. 2005;86:55–71. [PubMed] [Google Scholar]

27. Rodríguez M, Daniels B, Gunawardene S, Robbins GK. High frequency of vitamin D deficiency in ambulatory HIV-positive patients. AIDS Res Hum Retroviruses. 2009;25:9–14. [PubMed] [Google Scholar]

28. Van Den Bout-Van Den Beukel CJ, Fievez L, Michels M, et al. Vitamin D deficiency among HIV type 1-infected individuals in the Netherlands: effects of antiretroviral therapy. AIDS Res Hum Retroviruses. 2008;24:1375–1382. [PubMed] [Google Scholar]

29. Connor RI, Rigby WF. 1 alpha,25-Dihydroxyvitamin D3 inhibits productive infection of human monocytes by HIV-1. Biochem Biophys Res Commun. 1991;176:852–859. [PubMed] [Google Scholar]

30. Kizaki M, Ikeda Y, Simon KJ, Nanjo M, Koeffler HP. Effect of 1,25-dihydroxyvitamin D3 and its analogs on human immunodeficiency virus infection in monocytes/ macrophages. Leukemia. 1993;7:1525–1530. [PubMed] [Google Scholar]

31. Bergman P, Walter-Jallow L, Broliden K, Agerberth B, Söderlund J. The antimicrobial peptide LL-37 inhibits HIV-1 replication. Curr HIV Res. 2007;5:410–415. [PubMed] [Google Scholar]

32. Díaz A, Allen JE. Mapping immune response profiles: the emerging scenario from helminth immunology. Eur J Immunol. 2007;37:3319–3326. [PubMed] [Google Scholar]

33. Romani L. Cell mediated immunity to fungi: a reassessment. Med Mycol. 2008;46:515–529. [PubMed] [Google Scholar]

34. Actor JK, Olsen M, Jagannath C, Hunter RL. Relationship of survival, organism containment, and granuloma formation in acute murine tuberculosis. J Interferon Cytokine Res. 1999;19:1183–1193. [PubMed] [Google Scholar]

35. Wejse C. Vitamin D as supplementary treatment for tuberculosis—a double-blind randomized, placebo-controlled trial. Am J Respir Crit Care Med. 2009;179:843–850. [PubMed] [Google Scholar]

36. Martineau AR, Wilkinson RJ, Wilkinson KA, et al. A single dose of vitamin D enhances immunity to mycobacteria. Am J Respir Crit Care Med. 2007;176:208–213. [PubMed] [Google Scholar]

37. Nursyam EW, Amin Z, Rumende CM. The effect of vitamin D as supplementary treatment in patients with moderately advanced pulmonary tuberculous lesion. Acta Med Indones. 2006;38:3–5. [PubMed] [Google Scholar]

38. Morcos MM, Gabr AA, Samuel S, et al. Vitamin D administration to tuberculous children and its value. Boll Chim Farm. 1998;137:157–164. [PubMed] [Google Scholar]

39. Kawaura A. Inhibitory effect of long term 1alpha-hydroxyvitamin D3 administration on Helicobacter pylori infection. J Clin Biochem Nutr. 2006;38:103–106. [Google Scholar]

40. Moe SM, Zekonis M, Harezlak J, et al. A placebo-controlled trial to evaluate immunomodulatory effects of paricalcitol. Am J Kidney Dis. 2001;38:792–802. [PubMed] [Google Scholar]

41. Rehman PK. Sub-clinical rickets and recurrent infection. J Trop Pediatr. 1994;40:58. [PubMed] [Google Scholar]

42. Aloia JF, Li-Ng M. Re: epidemic influenza and vitamin D [with author reply] Epidemiol Infect. 2007;135:1095–1098. [PMC free article] [PubMed] [Google Scholar]

43. Avenell A, Cook JA, Maclennan GS, Macpherson GC. Vitamin D supplementation to prevent infections: a sub-study of a randomised placebo-controlled trial in older people (RECORD trial, ISRCTN 51647438) Age Ageing. 2007;36:574–577. [PubMed] [Google Scholar]

44. Kriesel JD, Spruance J. Calcitriol (1,25-dihydroxy-vitamin D3) coadministered with influenza vaccine does not enhance humoral immunity in human volunteers. Vaccine. 1999;17:1883–1888. [PubMed] [Google Scholar]

45. Arpadi SM, McMahon D, Abrams EJ, et al. Effect of bimonthly supplementation with oral cholecalciferol on serum 25-hydroxyvitamin D concentrations in HIV-infected children and adolescents. Pediatrics. 2009;123:e121–e126. [published correction appears in Pediatrics. 2009;123:1437] [PMC free article] [PubMed] [Google Scholar]

46. Snyman JR, de Sommers K, Steinmann MA, Lizamore DJ. Effects of calcitriol on eosinophil activity and antibody responses in patients with schistosomiasis. Eur J Clin Pharmacol. 1997;52:277–280. [PubMed] [Google Scholar]

47. Li-Ng M, Aloia JF, Pollack S, et al. A randomized controlled trial of vitamin D3 supplementation for the prevention of symptomatic upper respiratory tract infections. Epidemiol Infect. 2009;19:1–9. [PubMed] [Google Scholar]

48. Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357:266–281. [PubMed] [Google Scholar]

49. Grant AM, Avenell A, Campbell MK, et al. (RECORD Trial Group) Oral vitamin D3 and calcium for secondary prevention of low-trauma fractures in elderly people (Randomised Evaluation of Calcium or Vitamin D, RECORD): a randomised placebo-controlled trial. Lancet. 2005;365:1621–1628. [PubMed] [Google Scholar]

50. Aloia JF, Talwar SA, Pollack S, Yeh J. A randomized controlled trial of vitamin D3 supplementation in African American women. Arch Intern Med. 2005;165:1618–1623. [PMC free article] [PubMed] [Google Scholar]

51. Seaworth B, Drucker J, Starling J, Drucker R, Stevens C, Hamilton J. Hepatitis B vaccines in patients with chronic renal failure before dialysis. J Infect Dis. 1988;157:332–337. [PubMed] [Google Scholar]

52. Haug C, Müller F, Aukrust P, Frøland SS. Subnormal serum concentration of 1,25-vitamin D in human immunodeficiency virus infection: correlation with degree of immune deficiency and survival. J Infect Dis. 1994;169:889–893. [PubMed] [Google Scholar]

53. Range N, Changalucha J, Krarup H, Magnussen P, Andersen AB, Friis H. The effect of multi-vitamin/mineral supplementation on mortality during treatment of pulmonary tuberculosis: a randomised two-by-two factorial trial in Mwanza, Tanzania. Br J Nutr. 2006;95:762–770. [PubMed] [Google Scholar]

54. Villamor E, Mugusi F, Urassa W, et al. A trial of the effect of micronutrient supplementation on treatment outcome, T cell counts, morbidity, and mortality in adults with pulmonary tuberculosis. J Infect Dis. 2008;197:1499–1505. [PMC free article] [PubMed] [Google Scholar]


Vitamin D for prevention of respiratory tract infections

Can Vitamin D3 Help Prevent Infections?

Respiratory tract infections are conditions that affect the air passages.

These include acute infections that affect the lower respiratory tract and lungs, such as pneumonia and influenza (1), which are among the leading causes of death in children worldwide (2).

In 2015, 16% of all deaths in children under five years of age were attributed to pneumonia (2). These conditions may also have an impact on quality of life (3). Therefore, it is important to find interventions that could prevent respiratory conditions.

Vitamin D is a fat-soluble-vitamin, different from others in that a major source derives from UV light-induced conversion of its precursor under the skin. Dietary sources include fortified foods and supplements.

Studies have indicated that there is a high prevalence of vitamin D deficiency worldwide (4–5).

Vitamin D deficiency may affect the immune system as vitamin D plays an immunomodulation role (6), enhancing innate immunity by up-regulating the expression and secretion of antimicrobial peptides (7–8), which boosts mucosal defences.

Furthermore, recent meta-analyses have reported a protective effect of vitamin D supplementation on respiratory tract infections (9–12). Therefore, in this commentary we reviewed the applicability of such intervention and implementation in settings with limited resources these four systematic reviews and meta-analyses.

This commentary provides an overview of four systematic reviews and meta-analyses (9–12). Yakoob et al. (9) conducted a Cochrane review of individually- or cluster-randomized controlled trials assessing synthetic oral vitamin D supplementation and the incidence rate of respiratory tract infection in children under five years of age.

This review included trials of vitamin D supplementation at different doses and frequencies compared to a control group. The control group included placebo of propylene glycol or olive oil, or no intervention. The outcomes included in this review were incidence rate, duration, and severity of infections, particularly, pneumonia and diarrhoea.

Pneumonia was confirmed by chest radiograph.

Bergman et al.

(10) conducted a systematic review and meta-analysis of randomized controlled trials assessing vitamin D and incidence of respiratory tract infection, defined by each author as primary or secondary outcomes, including upper or lower infections in children and in adults; they excluded tuberculosis and fungal infections. The randomized trials compared vitamin D supplementation group to a control (no treatment or placebo) group. In this review, there were no limitations with regard to participant’s characteristics, vitamin D doses, and treatment duration.

Charan et al.

(11) assessed the effect of vitamin D supplementation on the prevention of respiratory tract infections through a meta-analysis of randomized placebo controlled clinical trials in children and in adults.

The outcome of this systematic review and meta-analysis was the episode of respiratory tract infection (pneumonia, influenza, common cold) in those randomized to the intervention compared to controls.

Martineau et al. (12) completed a systematic review and meta-analysis of randomized controlled trials with individual’s participant data. This review assessed the effect of vitamin D supplementation on acute respiratory tract infections in children and in adults.

These reviews used standard procedure of search terms and strategies, and presented clear search criteria and data analyses for conducting systematic reviews and meta-analyses.

Yakoob et al. (9) included four trials with a total of 3198 children from Afghanistan, Spain, and the USA. Pneumonia episodes (two trials reported this) were similar between those supplemented with vitamin D compared to controls (Rate Ratio [RR]: 1.06; 95% CI: 0.89, 1.26).

The trial from Afghanistan found an increase in repeat episodes of pneumonia with vitamin D supplementation (RR 1.69; 95% CI: 1.28, 2.21) but not when confirmed or unconfirmed pneumonia was combined (RR 1.06; 95% CI: 1.00, 1.13).

No study reported on duration of pneumonia or severity of infection.

Bergman et al.

(10) included 11 randomized placebo-controlled trials with 5660 individuals (average age was 16 years, ranging from 6 months to 75 years). The summarized results showed that vitamin D supplementation significantly decreased the risk of respiratory tract infections (odds ratio [OR]: 0.64; 95% CI: 0.49, 0.84; p=0.0014). Also, this review found that the protective effect of vitamin D was greater in studies using daily single doses (300-2000 IU/day) (OR 0.51; 95% CI: 0.39, 0.67) compared to large doses given at certain intervals (100,000 or 200,000 IU per month or every 3 months) (OR 0.86; 95% CI: 0.62, 1.20).

However, there was evidence of heterogeneity and publication bias among studies.

Five clinical trials were included in the review conducted by Charan et al. (11). The reduction of episodes of respiratory tract infections was significantly lower in vitamin D supplementation group compared to the control group (OR=0.58; 95% CI: 0.42, 0.81; p=0.001).

When analysed by age using fixed models, the protective effect of vitamin D supplementation was found among two trials reporting this in children (OR 0.58; 95% CI: 0.42, 0.81; P=0.001 in two trials) and among three trials reporting this in adults (OR 0.65; 95% CI: 0.47, 0.90; P=0.01).

However, when using random models, the effect remained significant in children (OR 0.58; 95% CI: 0.42, 0.81; P=0.001) and it was marginal in adults (OR 0.54; 95% CI: 0.28, 1.06; P=0.08).

This difference could be attributed to publication bias, low number of trials, different vitamin D doses and heterogeneity of participants.

Martineau et al. (12) included 25 randomized controlled trials, with a total of 10,933 participants aged 0-95 years from 14 different countries. Overall, there was a significant beneficial effect of vitamin D supplementation in decreasing the risk of experiencing at least one acute respiratory tract infection (OR 0.88; 95% CI: 0.81, 0.

96; P=0.003). This protective effect was seen in those not receiving bolus doses (OR 0.81; 95% CI: 0.72, 0.91) vs those receiving bolus doses of ≥30000 IU (OR 0.97; 95% CI: 0.86, 1.10). Also, this effect was seen among those receiving doses 2,000 IU. Furthermore, this protective effect was seen in children 1–16 years (OR 0.60; 95% CI: 0.46, 0.

77; P


Vitamin D protects against colds and flu, finds major global study

Can Vitamin D3 Help Prevent Infections?

Vitamin D supplements protect against acute respiratory infections including colds and flu, according to a study led by Queen Mary University of London (QMUL).

The study provides the most robust evidence yet that vitamin D has benefits beyond bone and muscle health, and could have major implications for public health policy, including the fortification of foods with vitamin D to tackle high levels of deficiency in the UK.

The results, published in The BMJ, are a new analysis of raw data from around 11,000 participants in 25 clinical trials conducted in 14 countries including the UK, USA, Japan, India, Afghanistan, Belgium, Italy, Australia and Canada. Individually, these trials yielded conflicting results, with some reporting that vitamin D protected against respiratory infections, and others showing no effect.

Lead researcher Professor Adrian Martineau from QMUL said: “This major collaborative research effort has yielded the first definitive evidence that vitamin D really does protect against respiratory infections. Our analysis of pooled raw data from each of the 10,933 trial participants allowed us to address the thorny question of why vitamin D 'worked' in some trials, but not in others.

“The bottom line is that the protective effects of vitamin D supplementation are strongest in those who have the lowest vitamin D levels, and when supplementation is given daily or weekly rather than in more widely spaced doses.

“Vitamin D fortification of foods provides a steady, low-level intake of vitamin D that has virtually eliminated profound vitamin D deficiency in several countries. By demonstrating this new benefit of vitamin D, our study strengthens the case for introducing food fortification to improve vitamin D levels in countries such as the UK where profound vitamin D deficiency is common.”

Vitamin D — the 'sunshine vitamin' — is thought to protect against respiratory infections by boosting levels of antimicrobial peptides — natural antibiotic- substances — in the lungs.

Results of the study fit with the observation that colds and 'flu are commonest in winter and spring, when levels of vitamin D are at their lowest.

They may also explain why vitamin D protects against asthma attacks, which are commonly triggered by respiratory viruses.

Daily or weekly supplementation halved the risk of acute respiratory infection in people with the lowest baseline vitamin D levels, below 25 nanomoles per litre (nmol/L).

However, people with higher baseline vitamin D levels also benefited, although the effect was more modest (10 per cent risk reduction).

Overall, the reduction in risk of acute respiratory infection induced by vitamin D was on a par with the protective effect of injectable 'flu vaccine against 'flu- illnesses.

Acute respiratory infections are a major cause of global morbidity and mortality. Upper respiratory infections such as colds and 'flu are the commonest reason for GP consultations and days off work.

Acute lower respiratory infections such as pneumonia are less common, but caused an estimated 2.65 million deaths worldwide in 2013.

Vitamin D supplementation is safe and inexpensive, so reductions in acute respiratory infections brought about by vitamin D supplementation could be highly cost-effective.

The study was conducted by a consortium of 25 investigators from 21 institutions worldwide and funded by the National Institute for Health Research.

Professor Hywel Williams, director of the NIHR Health Technology Assessment (HTA) Programme said: “The interesting findings of this large study are worthy of serious further debate. This study is yet another example of how the NIHR HTA Programme reaches the parts that other research funders may not tackle.”

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Journal Reference:

  1. Adrian R Martineau, David A Jolliffe, Richard L Hooper, Lauren Greenberg, John F Aloia, Peter Bergman, Gal Dubnov-Raz, Susanna Esposito, Davaasambuu Ganmaa, Adit A Ginde, Emma C Goodall, Cameron C Grant, Christopher J Griffiths, Wim Janssens, Ilkka Laaksi, Semira Manaseki-Holland, David Mauger, David R Murdoch, Rachel Neale, Judy R Rees, Steve Simpson, Iwona Stelmach, Geeta Trilok Kumar, Mitsuyoshi Urashima, Carlos A Camargo. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ, 2017; i6583 DOI: 10.1136/bmj.i6583