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Condition

Lower Respiratory Tract Infection

Lower respiratory tract infections affect the bronchi and lungs, below the voice box, and include bronchitis, bronchiolitis and pneumonia. Vitamin C and vitamin D are the leading candidates, yet vitamin D showed no clear difference in lower respiratory infection risk among 5,110 people, and a nasal resveratrol solution showed none for upper infections in 39 children. Evidence for each is very limited, and the other supplements studied have little direct trial data here.

Sources: PMID 39064639

Supplements studied
5
Graded outcomes
4
Trials
6
People studied
5,860

Evidence by supplement

  • Strong
  • Moderate
  • Limited
  • Very limited

5 supplements

Vitamin E

Vitamin E: outcomes studied for Lower Respiratory Tract Infection
GradeOutcomeEffectSizeStudiesPeopleStudies list
All-Cause Mortality

No effect

NoneNo effect2 studies451 people

Studies that measured all-cause mortality

WeightImproves (the measure goes down)1 study451 people

Studies that measured weight

HemoglobinImproves (the measure goes up)451 people
ImmunityImproves (the measure goes up)902 people
Upper Respiratory Tract Infection RiskChanges; see studies451 people

Resveratrol

Resveratrol: outcomes studied for Lower Respiratory Tract Infection
GradeOutcomeEffectSizeStudiesPeopleStudies list
Upper Respiratory Tract Infection Risk

No effect

NoneNo effect1 study39 people

Studies that measured upper respiratory tract infection risk

Upper Respiratory Tract Infection SymptomsImproves (the measure goes down)39 people

Lactobacillus Casei

  • Immunity
  • Immunoglobulin A: improves
  • Upper Respiratory Tract Infection Risk: changes; see studies
Lactobacillus Casei: outcomes studied for Lower Respiratory Tract Infection
GradeOutcomeEffectSizeStudiesPeopleStudies list
Immunity

No effect

NoneNo effect47 people
Immunoglobulin AImproves (the measure goes up)2 studies47 people

Studies that measured immunoglobulin a

Upper Respiratory Tract Infection RiskChanges; see studies47 people

Vitamin D

  • Lower Respiratory Tract Infection Risk
  • Upper Respiratory Tract Infection Risk: changes; see studies
  • Upper Respiratory Tract Infection Symptoms: improves
Vitamin D: outcomes studied for Lower Respiratory Tract Infection
GradeOutcomeEffectSizeStudiesPeopleStudies list
Lower Respiratory Tract Infection Risk

No effect

NoneNo effect5,110 people
Upper Respiratory Tract Infection RiskChanges; see studies13 studies10,220 people

Studies that measured upper respiratory tract infection risk

and 10 more on the Vitamin D page

Upper Respiratory Tract Infection SymptomsImproves (the measure goes down)13 studies156 people

Studies that measured upper respiratory tract infection symptoms

and 10 more on the Vitamin D page

Vitamin C

  • Upper Respiratory Tract Infection Symptoms: improves
Vitamin C: outcomes studied for Lower Respiratory Tract Infection
GradeOutcomeEffectSizeStudiesPeopleStudies list
Upper Respiratory Tract Infection SymptomsImproves (the measure goes down)24 studies57 people

Studies that measured upper respiratory tract infection symptoms

and 21 more on the Vitamin C page

Key findings

  • All-Cause MortalityVitamin E
  • Upper Respiratory Tract Infection RiskResveratrol
  • ImmunityLactobacillus Casei

The Lower Respiratory Tract Infection Support protocol

2 primary supplements · 3 supporting supplements

See the full protocol

Shop the evidence-backed picks

Support alongside medical care. These supplements are not a treatment for Lower Respiratory Tract Infection. If you are being treated for it, talk to your clinician before adding one: supplements can interact with medicines.

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Studies cited

56 studies from PubMed

  1. Vitamin E supplementation and cataract: randomized controlled trialOphthalmology · PMID 14711717
  2. Vitamin E and respiratory tract infections in elderly nursing home residents: a randomized controlled trialJAMA · PMID 15315997
  3. Vitamin E in the primary prevention of cardiovascular disease and cancer: the Women's Health Study: a randomized controlled trialJAMA · PMID 15998891
  4. Effect of vitamin D status and vitamin D supplementation on immune function and prevention of acute respiratory tract infections in dark-skinned individuals: a systematic review and meta-analysis.Public Health Nutr · PMID 39465641
  5. Therapeutic effect of vitamin D in acute lower respiratory infection: A randomized controlled trialClin Nutr ESPEN · PMID 29072165
  6. Preventive Effects of Vitamin D on Seasonal Influenza A in Infants: A Multicenter, Randomized, Open, Controlled Clinical TrialPediatr Infect Dis J · PMID 29315160
  7. Effects of vitamin D supplementation to children diagnosed with pneumonia in Kabul: a randomised controlled trialTrop Med Int Health · PMID 20723187
  8. Double-blind randomised controlled trial of vitamin D3 supplementation for the prevention of acute respiratory infection in older adults and their carers (ViDiFlu)Thorax · PMID 26063508
  9. Winter cholecalciferol supplementation at 55°N has little effect on markers of innate immune defense in healthy children aged 4-8 years: a secondary analysis from a randomized controlled trialEur J Nutr · PMID 29572676
  10. Effect of Vitamin D supplementation to reduce respiratory infections in children and adolescents in Vietnam: A randomized controlled trialInfluenza Other Respir Viruses · PMID 30328294
  11. Vitamin D3 supplementation in patients with frequent respiratory tract infections: a randomised and double-blind intervention studyBMJ Open · PMID 23242238
  12. Effect of monthly high-dose vitamin D supplementation on acute respiratory infections in older adults: A randomized controlled trialClin Infect Dis · PMID 31420647
  13. Vitamin D3 supplementation and upper respiratory tract infections in a randomized, controlled trialClin Infect Dis · PMID 24014734
  14. Vitamin D supplementation to prevent infections: a sub-study of a randomised placebo-controlled trial in older people (RECORD trial, ISRCTN 51647438)Age Ageing · PMID 17702768
  15. Effect of High-Dose vs Standard-Dose Wintertime Vitamin D Supplementation on Viral Upper Respiratory Tract Infections in Young Healthy ChildrenJAMA · PMID 28719693
  16. Vitamin D supplementation for the prevention of acute respiratory tract infection: a randomized, double-blinded trial among young Finnish menJ Infect Dis · PMID 20632889
  17. A randomized controlled trial of vitamin D3 supplementation for the prevention of symptomatic upper respiratory tract infectionsEpidemiol Infect · PMID 19296870
  18. Vitamin D₃ Supplementation Reduces the Symptoms of Upper Respiratory Tract Infection during Winter Training in Vitamin D-Insufficient Taekwondo Athletes: A Randomized Controlled TrialInt J Environ Res Public Health · PMID 30223447
  19. Intake of 25-Hydroxyvitamin D3 Reduces Duration and Severity of Upper Respiratory Tract Infection: A Randomized, Double-Blind, Placebo-Controlled, Parallel Group Comparison StudyJ Nutr Health Aging · PMID 29582888
  20. Vitamin D3 and gargling for the prevention of upper respiratory tract infections: a randomized controlled trialBMC Infect Dis · PMID 24885201
  21. Effect of vitamin D3 supplementation on upper respiratory tract infections in healthy adults: the VIDARIS randomized controlled trialJAMA · PMID 23032549
  22. Vitamin D supplementation and upper respiratory tract infections in adolescent swimmers: a randomized controlled trialPediatr Exerc Sci · PMID 25050610
  23. Vitamin D supplementation to prevent acute respiratory infections: individual participant data meta-analysisHealth Technol Assess · PMID 30675873
  24. Reduced primary care respiratory infection visits following pregnancy and infancy vitamin D supplementation: a randomised controlled trialActa Paediatr · PMID 25283480
  25. Randomized trial of vitamin D supplementation and risk of acute respiratory infection in MongoliaPediatrics · PMID 22908115
  26. High-Dose Monthly Vitamin D for Prevention of Acute Respiratory Infection in Older Long-Term Care Residents: A Randomized Clinical TrialJ Am Geriatr Soc · PMID 27861708
  27. The effects of prenatal vitamin D supplementation on respiratory and allergy-related outcomes in children: A systematic review and meta-analysis of randomized controlled trials.World Allergy Organ J · PMID 40535465
  28. Vitamin D Supplementation and the Risk of Colds in Patients with AsthmaAm J Respir Crit Care Med · PMID 26540136
  29. Double-blind randomised placebo-controlled trial of bolus-dose vitamin D3 supplementation in adults with asthma (ViDiAs)Thorax · PMID 25724847
  30. The clinical effects of vitamin C supplementation in elderly hospitalised patients with acute respiratory infectionsInt J Vitam Nutr Res · PMID 7814237
  31. Vitamin C supplementation reduces the incidence of postrace symptoms of upper-respiratory-tract infection in ultramarathon runnersAm J Clin Nutr · PMID 8185726
  32. Vitamin C and acute illness in Navajo school childrenN Engl J Med · PMID 787788
  33. The effect of vitamin C on upper respiratory infections in adolescent swimmers: a randomized trialEur J Pediatr · PMID 20689965
  34. A trial of ascorbic acid in the treatment of the common coldBr J Prev Soc Med · PMID 338079
  35. Blood ascorbic acid level in bioflavonoid and ascorbic acid therapy of common coldJ Am Med Assoc · PMID 13366735
  36. Vitamin C as a preventive medicine against common colds in childrenScand J Infect Dis · PMID 897573
  37. Evaluation of the efficacy of ascorbic acid in prophylaxis of induced rhinovirus 44 infection in manJ Infect Dis · PMID 4355208
  38. A randomized controlled trial of vitamin C in the prevention and amelioration of the common coldBr J Prev Soc Med · PMID 788820
  39. L-Ascorbic acid and D-isoascorbic acid in a common cold surveyAm J Clin Nutr · PMID 1099894
  40. Vitamin C prophylaxis in marine recruitsJAMA · PMID 368370
  41. The effectiveness of vitamin C in preventing and relieving the symptoms of virus-induced respiratory infectionsJ Manipulative Physiol Ther · PMID 10543583
  42. A controlled clinical trial of ascorbic acid for the common coldAnn N Y Acad Sci · PMID 1106302
  43. Mega-dose vitamin C in treatment of the common cold: a randomised controlled trialMed J Aust · PMID 11700812
  44. Trial of ascorbic acid in prevention of coldsBr Med J · PMID 4290259
  45. Vitamin C and the common cold: a second MZ Cotwin control studyActa Genet Med Gemellol · PMID 7048833
  46. A randomized controlled trial of the therapeutic effect of vitamin C in the common coldPractitioner · PMID 319446
  47. Therapeutic effect of vitamin C. A co-twin control studyJAMA · PMID 318715
  48. Ascorbic acid for the common cold. A prophylactic and therapeutic trialJAMA · PMID 163386
  49. Winter illness and vitamin C: the effect of relatively low dosesCan Med Assoc J · PMID 1091343
  50. Vitamin C and the common coldJ Soc Occup Med · PMID 162650
  51. Preventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled surveyAdv Ther · PMID 12201356
  52. Ascorbic acid and the common coldLancet · PMID 4113614
  53. Vitamin C and the common cold: a double-blind trialCan Med Assoc J · PMID 5057006
  54. Effects of Nasal Solution Incorporating Resveratrol and Carboxymethyl-Β-Glucan in Preschool Non-Atopic Children with Wheezing.Nutrients · PMID 39064639
  55. Effect of a probiotics supplementation on respiratory infections and immune and hormonal parameters during intense military trainingMil Med · PMID 17937368
  56. Daily probiotic's (Lactobacillus casei Shirota) reduction of infection incidence in athletesInt J Sport Nutr Exerc Metab · PMID 21411836