Woman with healthy support for respiratory immune system smelling flower

Nutrients to Support Respiratory Immune Health

Nutrients to Support Respiratory Immune Health

Last Section Update: 04/2021

Table of Contents

  1. Nutrients to Support Respiratory Immune Health
  2. How to Test Your Immune System
  3. Update History
  4. References

1 Nutrients to Support Respiratory Immune Health

  • Zinc. Zinc has demonstrated antiviral effects against several respiratory viruses, promoting their clearance from the airway surfaces, preventing their entry into cells, and suppressing viral replication. Using zinc in the form of a lozenge within 24 hours of symptom onset may reduce the duration and severity of a cold.1,2
  • Elderberry. Clinical research indicates elderberry extract, rich in anti-inflammatory and antioxidant polyphenols, may reduce influenza symptoms and shorten duration of illness when started within 48 hours of symptom onset.3
  • Probiotics. Multiple randomized controlled trials and several meta-analyses have shown probiotics reduce the risk of acute respiratory tract infections. Species of Lactobacillus and Bifidobacterium have been found to reduce the incidence and severity of upper respiratory viral infections, including the flu.4
  • Lactoferrin (as apolactoferrin). Lactoferrin, an immune modulator capable of enhancing antimicrobial immune activity while reducing inflammation, has exhibited a broad spectrum of activity against bacteria, fungi, protozoa, and viruses.5,6
  • Vitamin D. Numerous studies around the world have found correlations between low vitamin D status and increased risk of respiratory viral infections and poor outcomes.7
  • Curcumin. Numerous preclinical studies indicate curcumin may activate antiviral immunity, and it has demonstrated antiviral effects against a range of respiratory viruses. Curcumin also helps mitigate inflammation associated with the immune response to infection.8-12
  • Melatonin. In addition to its role in promoting healthy sleep, melatonin is an antioxidant with anti-inflammatory activity. Some researchers have suggested taking 3–10 mg of melatonin at bedtime for respiratory immune health.13,14
  • N-Acetylcysteine (NAC). NAC inhibits cellular entry and replication of some respiratory viruses, assists in clearing thickened mucous from the airways, and suppresses inflammatory signaling.15
  • Vitamin C. When initiated soon after symptom onset, vitamin C may reduce the duration of influenza-like respiratory illness symptoms such as fever, chills, and body pain.16-19
  • Selenium. Selenium has been shown in preclinical studies to reduce infectivity, replication, and virulence of several respiratory viruses.20-22
  • Licorice. Active constituents of licorice have demonstrated antiviral effects against viral causes of respiratory infection as well as other viruses. 23-25
  • Garlic. Garlic compounds have demonstrated antiviral activity against respiratory viruses, such as rhinoviruses and influenza viruses, and have broad antimicrobial activity against bacterial and fungal causes of illness.26
  • Andrographis. Multiple randomized controlled trials and two meta-analyses have found andrographis extract, alone and in herbal combinations, reduced symptoms of upper respiratory tract infections and may be especially helpful in alleviating cough and sore throat.31-36
  • Green Tea. Green tea catechins have demonstrated antiviral actions against influenza and other respiratory viruses. Green tea may help prevent viral respiratory infections and may decrease flu-like symptoms by reducing inflammation.37,38
  • Ginseng. Ginseng extracts have been shown to activate the antiviral immune response while reducing the inflammatory response, and clinical trials suggest it may lower risk of the flu and improve immune response to the flu vaccine.39,40
  • Echinacea. Echinacea may reduce the incidence of colds and sick days, as well as reducing the risk of recurrent infections.41,42
  • Beta-glucans. These prebiotic fibers may stimulate the body’s antimicrobial defense and prevent infection as well as decrease upper respiratory tract infection symptoms.43

The nutrients listed here may generally support respiratory immune health. Additional details are available in Life Extension’s protocols on Influenza, Common Cold, Pneumonia, and Immune Senescence.

2 How to Test Your Immune System

Several lab tests can shed light on various aspects of immune system function and response to infection. For instance, white blood cell (WBC) levels are often elevated in acute infections.44,45 And, paradoxically, lower levels of total WBCs or lymphocytes, the primary immune responder in viral infections, might be seen in severe infections.46,47

Assessing the numbers of different types of WBCs in a patient’s blood can help determine the type of pathogen (e.g., a virus or bacteria) that is causing the infection. This can be helpful in avoiding the overuse of unnecessary antibiotics since antibiotics do not work against viruses (which are the most common cause of acute respiratory infections).

High levels (or relative proportion) of neutrophils, another type of white blood cell, may be suggestive of a bacterial cause of a respiratory infection. Lower levels of WBCs may be seen in non-infectious diseases that affect the immune system, such as autoimmune disease or cancer, as well as with chronic use of glucocorticoid medications, which can hamper the body’s response in acute illness.48-50

Lab tests to assess other immune cell types can be insightful as well. For example, CD8+ killer T cells target and destroy cancer cells and cells infected with viruses, while macrophages (also called “big eaters”) engulf and destroy harmful bacteria.51-53 On the other hand, regulatory T cells help ensure the immune system does not over-react and drive chronic inflammation or autoimmune diseases.54

In certain settings of acute infection, specific tests such as reverse transcription polymerase chain reaction (RT-PCR) or antigen testing may be employed to determine if a patient’s symptoms are being caused by specific pathogens.55 Typically, a clinician will obtain a sample from the nose and/or throat to perform these types of tests.56 Antibody testing of levels of IgG, IgA, and/or IgM antibodies for specific pathogens may be useful to determine past or current infection and immunity status. Latent or chronic infections can contribute to immune dysregulation and a poor response to acute infection.

Table 1 below summarizes these and several other key laboratory tests that may help assess the immune system’s response to infectious agents, as well as tests to assess levels of nutrients that may influence immune function.

Table 1: Laboratory Assessment of Immune Parameters
Test
Description
Optimal Levels
Nutrients Related to Immune Function
Vitamin D (25-hydroxy vitamin D)
Many studies have found associations between low vitamin D levels and impaired immune function
50 – 80 ng/mL
Vitamin C, plasma
Plays a role in many aspects of immune cell function and metabolism
>1.2 mg/dL
Zinc, plasma or serum
Involved in several aspects of immune cell function, including regulating intracellular signaling pathways in innate and adaptive immune cells
>85 μg/dL
Acute Infection and Immune Function Tests
White blood cell (WBC) count
  • Neutrophils
  • Eosinophils
  • Basophils
  • Lymphocytes
  • Monocytes
Typically, a part of a complete blood count (CBC); abnormal levels may be sign of infection, blood cancer, or immune system disorder
Reverse transcription polymerase chain reaction (RT-PCR)
RT-PCR testing amplifies genetic material to determine the cause of infection and is more sensitive than antigen testing
Antigen tests
Rapid antigen tests help determine the cause of infection but are less accurate than RT-PCR
IgG, IgA, IgM antibodies to specific pathogens
Useful to assess for past or current infection and immunity status
  
C-reactive protein (hs-CRP)
Highly sensitive marker of inflammation that indicates immune activation, possibly due to conditions such as cancer, infection, injury, or autoimmune disease; correlates with cardiovascular risk
Men <0.55 mg/L
 
Women <1.0 mg/L
Cytokines, eg, TNF-α and interleukins IL-1beta, IL-6, IL-8
Proteins that are critical mediators of the inflammatory response
Natural Killer (NK) cell Function
Assesses functional (ie, cell-killing) capacity of NK cells
Natural Killer (NK) cell surface antigen (CD3-CD56+ Marker Analysis)
Determines levels of NK cells in circulation
Immunoglobulins IgA, IgG, IgM
Elevated in some autoimmune diseases, multiple myeloma, and acute and chronic infections; decreased in immune deficiencies
T-Lymphocyte helper/suppressor profile
May be helpful in assessing immunodeficiency states
Cortisol and dehydroepiandrosterone sulfate (DHEA-S)
Cortisol is immunosuppressive, while DHEA stimulates immune function; an imbalance between these hormones may contribute to immune dysregulation

2021

  • Apr: Initial publication

Disclaimer and Safety Information

This information (and any accompanying material) is not intended to replace the attention or advice of a physician or other qualified health care professional. Anyone who wishes to embark on any dietary, drug, exercise, or other lifestyle change intended to prevent or treat a specific disease or condition should first consult with and seek clearance from a physician or other qualified health care professional. Pregnant women in particular should seek the advice of a physician before using any protocol listed on this website. The protocols described on this website are for adults only, unless otherwise specified. Product labels may contain important safety information and the most recent product information provided by the product manufacturers should be carefully reviewed prior to use to verify the dose, administration, and contraindications. National, state, and local laws may vary regarding the use and application of many of the therapies discussed. The reader assumes the risk of any injuries. The authors and publishers, their affiliates and assigns are not liable for any injury and/or damage to persons arising from this protocol and expressly disclaim responsibility for any adverse effects resulting from the use of the information contained herein.

The protocols raise many issues that are subject to change as new data emerge. None of our suggested protocol regimens can guarantee health benefits. Life Extension has not performed independent verification of the data contained in the referenced materials, and expressly disclaims responsibility for any error in the literature.

  1. Zinc lozenges reduce the duration of common cold symptoms. Nutrition reviews. Mar 1997;55(3):82-5. doi:10.1111/j.1753-4887.1997.tb01601.x
  2. Wang MX, Win SS, Pang J. Zinc Supplemen
  3. tation Reduces Common Cold Duration among Healthy Adults: A Systematic Review of Randomized Controlled Trials with Micronutrients Supplementation. Am J Trop Med Hyg. Jul 2020;103(1):86-99. doi:10.4269/ajtmh.19-0718
  4. Wieland LS, Piechotta V, Feinberg T, et al. Elderberry for prevention and treatment of viral respiratory illnesses: a systematic review. BMC Complement Med Ther. Apr 7 2021;21(1):112. doi:10.1186/s12906-021-03283-5
  5. Wang F, Pan B, Xu S, et al. A meta-analysis reveals the effectiveness of probiotics and prebiotics against respiratory viral infection. Bioscience reports. Mar 26 2021;41(3)doi:10.1042/bsr20203638
  6. Vitetta L, Coulson S, Beck SL, Gramotnev H, Du S, Lewis S. The clinical efficacy of a bovine lactoferrin/whey protein Ig-rich fraction (Lf/IgF) for the common cold: a double blind randomized study. Complementary therapies in medicine. Jun 2013;21(3):164-71. doi:10.1016/j.ctim.2012.12.006
  7. Superti F, Agamennone M, Pietrantoni A, Ammendolia MG. Bovine Lactoferrin Prevents Influenza A Virus Infection by Interfering with the Fusogenic Function of Viral Hemagglutinin. Viruses. Jan 11 2019;11(1)doi:10.3390/v11010051
  8. Martineau AR, Jolliffe DA, Hooper RL, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ (Clinical research ed). Feb 15 2017;356:i6583. doi:10.1136/bmj.i6583
  9. Dai J, Gu L, Su Y, et al. Inhibition of curcumin on influenza A virus infection and influenzal pneumonia via oxidative stress, TLR2/4, p38/JNK MAPK and NF-κB pathways. International immunopharmacology. Jan 2018;54:177-187. doi:10.1016/j.intimp.2017.11.009
  10. Han S, Xu J, Guo X, Huang M. Curcumin ameliorates severe influenza pneumonia via attenuating lung injury and regulating macrophage cytokines production. Clin Exp Pharmacol Physiol. Jan 2018;45(1):84-93. doi:10.1111/1440-1681.12848
  11. Obata K, Kojima T, Masaki T, et al. Curcumin prevents replication of respiratory syncytial virus and the epithelial responses to it in human nasal epithelial cells. PLoS One. 2013;8(9):e70225. doi:10.1371/journal.pone.0070225
  12. Xu Y, Liu L. Curcumin alleviates macrophage activation and lung inflammation induced by influenza virus infection through inhibiting the NF-κB signaling pathway. Influenza Other Respir Viruses. Sep 2017;11(5):457-463. doi:10.1111/irv.12459
  13. Zuccotti GV, Trabattoni D, Morelli M, Borgonovo S, Schneider L, Clerici M. Immune modulation by lactoferrin and curcumin in children with recurrent respiratory infections. Journal of biological regulators and homeostatic agents. Apr-Jun 2009;23(2):119-23.
  14. Silvestri M, Rossi GA. Melatonin: its possible role in the management of viral infections--a brief review. Italian journal of pediatrics. 2013;39:61. doi:10.1186/1824-7288-39-61
  15. Habtemariam S, Daglia M, Sureda A, Selamoglu Z, Gulhan MF, Nabavi SM. Melatonin and Respiratory Diseases: A Review. Current topics in medicinal chemistry. 2017;17(4):467-488. doi:10.2174/1568026616666160824120338
  16. Schloss J, Leach M, Brown D, Hannan N, Kendall-Reed P, Steel A. The effects of N-acetyl cysteine on acute viral respiratory infections in humans: A rapid review. Adv Integr Med. Dec 2020;7(4):232-239. doi:10.1016/j.aimed.2020.07.006
  17. Constantini NW, Dubnov-Raz G, Eyal BB, Berry EM, Cohen AH, Hemilä H. The effect of vitamin C on upper respiratory infections in adolescent swimmers: a randomized trial. Eur J Pediatr. Jan 2011;170(1):59-63. doi:10.1007/s00431-010-1270-z
  18. Garaiova I, Muchová J, Nagyová Z, et al. Probiotics and vitamin C for the prevention of respiratory tract infections in children attending preschool: a randomised controlled pilot study. European journal of clinical nutrition. Mar 2015;69(3):373-9. doi:10.1038/ejcn.2014.174
  19. Sasazuki S, Sasaki S, Tsubono Y, Okubo S, Hayashi M, Tsugane S. Effect of vitamin C on common cold: randomized controlled trial. European journal of clinical nutrition. Jan 2006;60(1):9-17. doi:10.1038/sj.ejcn.1602261
  20. Van Straten M, Josling P. Preventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled survey. Adv Ther. May-Jun 2002;19(3):151-9. doi:10.1007/bf02850271
  21. Lee YH, Lee SJ, Lee MK, Lee WY, Yong SJ, Kim SH. Serum selenium levels in patients with respiratory diseases: a prospective observational study. J Thorac Dis. Aug 2016;8(8):2068-78. doi:10.21037/jtd.2016.07.60
  22. Yu L, Sun L, Nan Y, Zhu LY. Protection from H1N1 influenza virus infections in mice by supplementation with selenium: a comparison with selenium-deficient mice. Biol Trace Elem Res. Jun 2011;141(1-3):254-61. doi:10.1007/s12011-010-8726-x
  23. Shojadoost B, Taha-Abdelaziz K, Alkie TN, et al. Supplemental dietary selenium enhances immune responses conferred by a vaccine against low pathogenicity avian influenza virus. Veterinary immunology and immunopathology. Sep 2020;227:110089. doi:10.1016/j.vetimm.2020.110089
  24. Feng Yeh C, Wang KC, Chiang LC, Shieh DE, Yen MH, San Chang J. Water extract of licorice had anti-viral activity against human respiratory syncytial virus in human respiratory tract cell lines. Journal of ethnopharmacology. Jul 9 2013;148(2):466-73. doi:10.1016/j.jep.2013.04.040
  25. Grienke U, Braun H, Seidel N, et al. Computer-guided approach to access the anti-influenza activity of licorice constituents. J Nat Prod. Mar 28 2014;77(3):563-70. doi:10.1021/np400817j
  26. Utsunomiya T, Kobayashi M, Pollard RB, Suzuki F. Glycyrrhizin, an active component of licorice roots, reduces morbidity and mortality of mice infected with lethal doses of influenza virus. Antimicrob Agents Chemother. Mar 1997;41(3):551-6. doi:10.1128/aac.41.3.551
  27. Wu W, Li R, Li X, et al. Quercetin as an Antiviral Agent Inhibits Influenza A Virus (IAV) Entry. Viruses. Dec 25 2015;8(1)doi:10.3390/v8010006
  28. Hu X-Y, Wu R-H, Logue M, et al. Andrographis paniculata (Chuān Xīn Lián) for symptomatic relief of acute respiratory tract infections in adults and children: A systematic review and meta-analysis. PloS one. 2017;12(8):e0181780-e0181780. doi:10.1371/journal.pone.0181780
  29. Jiang M, Sheng F, Zhang Z, et al. Andrographis paniculata (Burm.f.) Nees and its major constituent andrographolide as potential antiviral agents. Journal of ethnopharmacology. May 23 2021;272:113954. doi:10.1016/j.jep.2021.113954
  30. Banerjee S, Kar A, Mukherjee PK, Haldar PK, Sharma N, Katiyar CK. Immunoprotective potential of Ayurvedic herb Kalmegh (Andrographis paniculata) against respiratory viral infections - LC-MS/MS and network pharmacology analysis. Phytochemical analysis : PCA. Nov 9 2020;doi:10.1002/pca.3011
  31. Coon JT, Ernst E. Andrographis paniculata in the treatment of upper respiratory tract infections: a systematic review of safety and efficacy. Planta Med. Apr 2004;70(4):293-8. doi:10.1055/s-2004-818938
  32. Kligler B, Ulbricht C, Basch E, et al. Andrographis paniculata for the treatment of upper respiratory infection: a systematic review by the natural standard research collaboration. Explore (New York, NY). Jan 2006;2(1):25-9. doi:10.1016/j.explore.2005.08.008
  33. Saxena RC, Singh R, Kumar P, et al. A randomized double blind placebo controlled clinical evaluation of extract of Andrographis paniculata (KalmCold) in patients with uncomplicated upper respiratory tract infection. Phytomedicine. Mar 2010;17(3-4):178-85. doi:10.1016/j.phymed.2009.12.001
  34. Kaihatsu K, Yamabe M, Ebara Y. Antiviral Mechanism of Action of Epigallocatechin-3-O-gallate and Its Fatty Acid Esters. Molecules (Basel, Switzerland). Sep 27 2018;23(10)doi:10.3390/molecules23102475
  35. Xu J, Xu Z, Zheng W. A Review of the Antiviral Role of Green Tea Catechins. Molecules (Basel, Switzerland). Aug 12 2017;22(8)doi:10.3390/molecules22081337
  36. Antonelli M, Donelli D, Firenzuoli F. Ginseng integrative supplementation for seasonal acute upper respiratory infections: A systematic review and meta-analysis. Complementary therapies in medicine. Aug 2020;52:102457. doi:10.1016/j.ctim.2020.102457
  37. Iqbal H, Rhee DK. Ginseng alleviates microbial infections of the respiratory tract: a review. J Ginseng Res. Mar 2020;44(2):194-204. doi:10.1016/j.jgr.2019.12.001
  38. Ross SM. Echinacea purpurea: A Proprietary Extract of Echinacea purpurea Is Shown to be Safe and Effective in the Prevention of the Common Cold. Holistic nursing practice. Jan-Feb 2016;30(1):54-7. doi:10.1097/hnp.0000000000000130
  39. Shah SA, Sander S, White CM, Rinaldi M, Coleman CI. Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis. Lancet Infect Dis. Jul 2007;7(7):473-80. doi:10.1016/s1473-3099(07)70160-3
  40. Dharsono T, Rudnicka K, Wilhelm M, Schoen C. Effects of Yeast (1,3)-(1,6)-Beta-Glucan on Severity of Upper Respiratory Tract Infections: A Double-Blind, Randomized, Placebo-Controlled Study in Healthy Subjects. J Am Coll Nutr. Jan 2019;38(1):40-50. doi:10.1080/07315724.2018.1478339
  41. Sexton DJM, M. T. UpToDate. The common cold in adults: Diagnosis and clinical features. Last updated 12/27/19. Accessed 09/18/20. 2019;
  42. Krammer F, Smith GJD, Fouchier RAM, et al. Influenza. Nature reviews Disease primers. Jun 28 2018;4(1):3. doi:10.1038/s41572-018-0002-y
  43. Salih W, Schembri S, Chalmers JD. Simplification of the IDSA/ATS criteria for severe CAP using meta-analysis and observational data. The European respiratory journal. Mar 2014;43(3):842-51. doi:10.1183/09031936.00089513
  44. Lalueza A, Folgueira D, Díaz-Pedroche C, et al. Severe lymphopenia in hospitalized patients with influenza virus infection as a marker of a poor outcome. Infect Dis (Lond). Jul 2019;51(7):543-546. doi:10.1080/23744235.2019.1598572
  45. Fauci AS, Dale DC, Balow JE. Glucocorticosteroid therapy: mechanisms of action and clinical considerations. Ann Intern Med. Mar 1976;84(3):304-15. doi:10.7326/0003-4819-84-3-304
  46. McElhaney JE, Zhou X, Talbot HK, et al. The unmet need in the elderly: how immunosenescence, CMV infection, co-morbidities and frailty are a challenge for the development of more effective influenza vaccines. Vaccine. Mar 9 2012;30(12):2060-7. doi:10.1016/j.vaccine.2012.01.015
  47. Risitano AM, Maciejewski JP, Selleri C, Rotoli B. Function and malfunction of hematopoietic stem cells in primary bone marrow failure syndromes. Curr Stem Cell Res Ther. Jan 2007;2(1):39-52. doi:10.2174/157488807779316982
  48. Farhood B, Najafi M, Mortezaee K. CD8(+) cytotoxic T lymphocytes in cancer immunotherapy: A review. J Cell Physiol. Jun 2019;234(6):8509-8521. doi:10.1002/jcp.27782
  49. Mittrücker H-W, Visekruna A, Huber M. Heterogeneity in the differentiation and function of CD8+ T cells. Archivum immunologiae et therapiae experimentalis. 2014;62(6):449-458.
  50. Benoit M, Desnues B, Mege J-L. Macrophage polarization in bacterial infections. The Journal of Immunology. 2008;181(6):3733-3739.
  51. Shevach EM, McHugh RS, Piccirillo CA, Thornton AM. Control of T‐cell activation by CD4+ CD25+ suppressor T cells. Immunological reviews. 2001;182(1):58-67.
  52. Uyeki TM, Bernstein HH, Bradley JS, et al. Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. Mar 5 2019;68(6):e1-e47. doi:10.1093/cid/ciy866
  53. Lieberman D, Lieberman D, Shimoni A, Keren-Naus A, Steinberg R, Shemer-Avni Y. Identification of respiratory viruses in adults: nasopharyngeal versus oropharyngeal sampling. J Clin Microbiol. Nov 2009;47(11):3439-43. doi:10.1128/jcm.00886-09