Life Extension Magazine®
Woman blowing nose with age-related declined immune response

Refuel Your Immune System

Supporting a healthy immune response requires fundamental nutrition.

Scientifically reviewed by: Dr Gary Gonzalez, MD, on May 2021. Written By Michael Downey.

With age, immune function markedly declines along with the body’s natural defenses.1

Until a method to fully reverse this degenerative process is validated, the following nutrients can help support a healthy immune response:

  • Vitamin C
  • Quercetin
  • Vitamin D
  • Zinc
  • Probiotic Lactobacillus rhamnosus CRL1505
  • S. cerevisiae fermentate

Taking these daily may help defend against infectious agents.

Vitamin C

Virus in lung leading to respiratory tract infection

The activity of many immune cells is closely related to their vitamin C content.

This is especially true for phagocytes, the cells that engulf and destroy bacteria and other infecting organisms, and T-cells, which regulate and direct other immune cells.2

Studies show that some immune functions can be improved by taking vitamin C.3,4

For example, vitamin C deficiency is associated in some studies with increased frequency and duration of colds.4

In a human clinical study, oral intake of vitamin C has been shown to reduce the duration of colds by an average of 9.4%. It may also help prevent viral respiratory tract infections and reduce their severity.5

Evidence from basic research shows that vitamin C promotes a healthy immune system by:

  • Enhancing the function and promoting the growth, maturation, and survival of immune cells that fight infection,6,7
  • Increasing levels of interferons, the “warning signals” produced by the body that trigger protective immune mechanisms,8
  • Neutralizing excess free radicals caused by infections, limiting oxidative damage and reducing severity of illness,9
  • Aiding in the production of the structural protein collagen, which allows our skin and the linings of our respiratory and digestive tracts to maintain a protective barrier against infection,10
  • Lowering levels of histamine, a pro-inflammatory compound11 that plays a role in infections,12 and causes symptoms of allergy,13,14 and
  • As indicated by preclinical studies, vitamin C plays a role in reducing excess levels of other pro-inflammatory compounds, countering inflammation caused by infection and injury, and promoting tissue healing.

The human body cannot produce or effectively store vitamin C. What that means is, in order to maintain optimal immunity, it’s a great idea to replenish your supply through daily supplementation.

Quercetin

Research has shown that the plant flavonoid quercetin can support a prompt immune response to common colds and other upper respiratory tract infections. These studies found that adults taking quercetin were less likely to develop these illnesses.

One study found that only 5% of people taking quercetin got sick during a two-week period (after three days of intense workouts), while 45% of those taking a placebo developed colds.19

In another study of physically fit middle-aged and older adults, daily quercetin intake reduced the number of sick days taken for colds by 31% and reduced the severity of symptoms by 36%.20

Quercetin may also be effective against bacterial infections.

In animal studies, it’s been shown to decrease the infection rate and inflammatory response to Helicobacter pylori, the cause of many ulcers and some potential cancers of the stomach.21,22

Quercetin also reduced inflammatory responses and strengthened host defenses against Salmonella bacteria in a cell-based model of infection.23

Salmonella bacteria cause roughly 26,500 hospitalizations in the U.S. every year and are especially dangerous in older adults.24

Evidence from epidemiological studies shows that people with the highest quercetin intake have reduced risk for many different deadly cancers, including lung, colon, and gastric cancers.25-27

It can be difficult for the body to absorb quercetin.28

Researchers solved this problem by integrating it into a phytosome, a type of fatty substance that serves as a carrier. This makes it up to 50 times more bioavailable (absorbable) than standard quercetin.29

Vitamin D

Vitamin D fortifies the immune system, helping to protect the body from infections, and lessening their severity. It may do this by:30-34

  • Interfering with the ability of viruses to replicate,
  • Supporting and helping to repair cellular linings in the body, including lung airways,
  • Boosting production of proteins that are protective against infection, and
  • Helping to prevent the immune system from producing excess pro-inflammatory compounds in the lungs.

Meta-analyses of clinical trials have shown that vitamin D protects against respiratory tract infections.35,36

In addition, low vitamin D levels are associated with higher rates of many chronic diseases, including cardiovascular disease, cognitive decline, and cancer.37

Annual blood tests can let people know whether they are taking the correct dosage to ensure optimal blood levels of vitamin D.

If you do not already maintain an optimal blood level of 25-hydroxyvitamin D of 50 to 80ng/mL, then take between 5,000 to 8,000 IU of vitamin D daily, with meals.

What you need to know

Zinc supplement and apple that can boost the immune system

Support a Healthy Immune System

  • In order to live long, healthy lives, we need our immune system to function at peak form on a daily basis. Several nutrients can help do that.
  • Vitamin C helps increase levels of antibody-producing cells (lymphocytes), boosts function of infection-engulfing neutrophils, and helps NK (natural killer) cell activity.56,57
  • Quercetin reduces inflammatory immune cells, cuts histamine levels, relaxes airway smooth muscle, inhibits replication and infectivity of cold-causing viruses, and reduces senescent cells and their pro-inflammatory signaling.58-60
  • Vitamin D interferes with virus replication and modulates the immune response via receptors on various immune cell types, thus supporting antimicrobial defenses while limiting inflammatory signaling.61
  • Zinc is key to maintaining the integrity of the immune system. It helps with the normal development and function of natural killer cells, lymphocytes, neutrophils, and macrophages.62
  • A probiotic strain, Lactobacillus rhamnosus CRL1505, significantly boosts levels of secretory IgA—critical antibodies that target both viral and bacterial invaders in the upper respiratory tract—thus providing a security system against cold and flu viruses within mucosal membranes.44,45,47,48
  • S. cerevisiae fermentate supports NK (natural killer) cell activity, production of secretory IgA, a balanced response to environmental allergens, and defense against colds.50-55

Zinc

Shield with zinc periodic symbol boosting immune system

Zinc deficiency is quite common in the elderly.38 It is thought to result from reduced zinc consumption and absorption in older individuals.39

This may compromise the function of the immune system and contribute to atherosclerosis, cancer, neurological disorders, autoimmune diseases, and other age-related conditions.40,41

The decline in immune function that happens with aging has been associated with both disease and death.42

By restoring zinc levels, aging adults may be able to partially slow immune function decline and protect against chronic inflammation.

Oral intake of zinc in the elderly has been shown to boost the stress response of white blood cells, providing an immune system anti-aging mechanism.43

Probiotic L. rhamnosus CRL1505

The immune system makes proteins called antibodies that fight bacteria, viruses, and toxins.

One of the most common antibodies, called secretory IgA (immunoglobulin A), is found in mucosal membranes.

IgA acts as the body’s built-in security system within mucosal membranes that line the nose and upper respiratory tract.44

Having adequate IgA levels is critical because these antibodies target both viral and bacterial invaders in the upper respiratory tract. This IgA activity can prevent cold and flu viruses from gaining a foothold and wreaking havoc on the respiratory tract.44

Scientists studying the beneficial live micro-organisms known as probiotics identified a specific bacterial strain that, in a preclinical model, significantly increased levels of secretory IgA.45

Originally isolated from goat’s milk in northwestern Argentina,46 the bacterium Lactobacillus rhamnosus CRL1505 has been shown in preclinical studies to help inhibit viruses and bacteria that can cause:45,47

In a clinical trial, one group of healthy male and female children consumed a yogurt drink five days a week that contained 100 million CFU (colony-forming units) of L. rhamnosus CRL1505. A second group consumed a drink that did not contain the probiotic.

The children ranged in age from two to five years, a population that is particularly susceptible to respiratory infections.48

Over six months, compared to the placebo group, the children in the probiotic group had:48

  • 61% fewer cases of tonsillitis and pharyngitis (a throat infection),
  • 55% fewer cases of cold or flu,
  • 49% fewer infections,
  • 46% fewer cases of fever, and
  • 33% less need for antibiotic use.

Daily intake of L. rhamnosus CRL1505 can provide protection against viral and bacterial infections.

S. cerevisiae fermentate Fights Allergies and Provides Immune Benefits

Smiling woman supplementing with S. cervisiae fermentate

The immune effects of S. cerevisiae fermentate were discovered by accident.

A company in Cedar Rapids, Iowa, had been producing a specialized yeast culture when it became apparent that its factory workers—who were exposed to the yeast daily, through inhalation—were taking far fewer sick days than its office workers.49

S. cerevisiae fermentate helps promote the body’s immune response when it encounters environmental allergens, like pollen.

At least six placebo-controlled clinical trials have validated its ability to protect against allergies and colds.50-55

In one study, subjects took either 500 mg of S. cerevisiae fermentate daily or a placebo for five weeks during the beginning of allergy season.50

Subjects in the placebo group did not see a change in their seasonal allergies.

The group supplementing with the S. cerevisiae fermentate saw improvements. Half of the treated male volunteers reported a complete absence of allergy symptoms, which returned within two weeks once they stopped taking the yeast fermentate.

In two other studies, subjects receiving S. cerevisiae fermentate reported shorter duration of symptoms and better response to immune challenge, compared to those taking a placebo.53,54

S. cerevisiae fermentate appears to work by promoting natural killer cell activity as well as the production of secretory IgA—two key players in our body’s immune defenses.50,51

In one study, subjects taking 500 mg of S. cerevisiae fermentate daily for eight weeks experienced an increase in secretory IgA.50

A placebo-controlled, double-blind study found that yeast fermentate increased markers of natural killer cell activity—after just a single 500 mg dose.51

Summary

Aging weakens the immune system, leaving us vulnerable to viral and bacterial infections, including colds, flu, and upper respiratory infections—and increases the risk of cancer.

Select nutrients help the immune system function optimally to kill pathogens, and can help prevent the chronic, low-level inflammation that is associated with numerous degenerative diseases linked to aging.

These critical nutrients include vitamin C, quercetin, vitamin D, zinc, the probiotic strain L. rhamnosus CRL1505 and S. cerevisiae fermentate.

They can help support a healthy immune system and may offer protection against viral and bacterial infection, cancers, and other illnesses.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.

References

  1. Aiello A, Farzaneh F, Candore G, et al. Immunosenescence and Its Hallmarks: How to Oppose Aging Strategically? A Review of Potential Options for Therapeutic Intervention. Front Immunol. 2019;10:2247.
  2. Strohle A, Wolters M, Hahn A. Micronutrients at the interface between inflammation and infection--ascorbic acid and calciferol: part 1, general overview with a focus on ascorbic acid. Inflamm Allergy Drug Targets. 2011 Feb;10(1):54-63.
  3. Wintergerst ES, Maggini S, Hornig DH. Immune-enhancing role of vitamin C and zinc and effect on clinical conditions. Ann Nutr Metab. 2006;50(2):85-94.
  4. Johnston CS, Barkyoumb GM, Schumacher SS. Vitamin C supplementation slightly improves physical activity levels and reduces cold incidence in men with marginal vitamin C status: a randomized controlled trial. Nutrients. 2014 Jul 9;6(7):2572-83.
  5. Hemila H. Vitamin C and Infections. Nutrients. 2017 Mar 29;9(4).
  6. Huijskens MJ, Walczak M, Koller N, et al. Technical advance: ascorbic acid induces development of double-positive T cells from human hematopoietic stem cells in the absence of stromal cells. J Leukoc Biol. 2014 Dec;96(6):1165-75.
  7. Huijskens MJ, Walczak M, Sarkar S, et al. Ascorbic acid promotes proliferation of natural killer cell populations in culture systems applicable for natural killer cell therapy. Cytotherapy. 2015 May;17(5):613-20.
  8. Available at: https://lpi.oregonstate.edu/mic/health-disease/immunity. Accessed June 18, 2021.
  9. Iqbal K, Khan A, Khan Khattak MA. Biological significance of ascorbic acid (vitamin C) in human health - a review. Pakistan Journal of Nutrition. 2004;3(1):5-13.
  10. Carr AC, Maggini S. Vitamin C and Immune Function. Nutrients. 2017 Nov 3;9(11).
  11. Branco A, Yoshikawa FSY, Pietrobon AJ, et al. Role of Histamine in Modulating the Immune Response and Inflammation. Mediators Inflamm. 2018 2018/08/27;2018:9524075.
  12. Smuda C, Bryce PJ. New developments in the use of histamine and histamine receptors. Curr Allergy Asthma Rep. 2011 Apr;11(2):94-100.
  13. Johnston CS, Martin LJ, Cai X. Antihistamine effect of supplemental ascorbic acid and neutrophil chemotaxis. J Am Coll Nutr. 1992 Apr;11(2):172-6.
  14. Johnston CS, Solomon RE, Corte C. Vitamin C depletion is associated with alterations in blood histamine and plasma free carnitine in adults. J Am Coll Nutr. 1996 Dec;15(6):586-91.
  15. Mohammed BM, Fisher BJ, Kraskauskas D, et al. Vitamin C promotes wound healing through novel pleiotropic mechanisms. Int Wound J. 2016 Aug;13(4):572-84.
  16. Gao YL, Lu B, Zhai JH, et al. The Parenteral Vitamin C Improves Sepsis and Sepsis-Induced Multiple Organ Dysfunction Syndrome via Preventing Cellular Immunosuppression. Mediators Inflamm. 2017;2017:4024672.
  17. Kim Y, Kim H, Bae S, et al. Vitamin C Is an Essential Factor on the Anti-viral Immune Responses through the Production of Interferon-alpha/beta at the Initial Stage of Influenza A Virus (H3N2) Infection. Immune Netw. 2013 Apr;13(2):70-4.
  18. Mohammed BM, Fisher BJ, Kraskauskas D, et al. Vitamin C: a novel regulator of neutrophil extracellular trap formation. Nutrients. 2013 Aug 9;5(8):3131-51.
  19. Nieman DC, Henson DA, Gross SJ, et al. Quercetin reduces illness but not immune perturbations after intensive exercise. Med Sci Sports Exerc. 2007 Sep;39(9):1561-9.
  20. Heinz SA, Henson DA, Austin MD, et al. Quercetin supplementation and upper respiratory tract infection: A randomized community clinical trial. Pharmacol Res. 2010 Sep;62(3):237-42.
  21. Gonzalez-Segovia R, Quintanar JL, Salinas E, et al. Effect of the flavonoid quercetin on inflammation and lipid peroxidation induced by Helicobacter pylori in gastric mucosa of guinea pig. J Gastroenterol. 2008;43(6):441-7.
  22. Brown JC, Wang J, Kasman L, et al. Activities of muscadine grape skin and quercetin against Helicobacter pylori infection in mice. J Appl Microbiol. 2011 Jan;110(1):139-46.
  23. Paolillo R, Carratelli CR, Rizzo A. Effect of resveratrol and quercetin in experimental infection by Salmonella enterica serovar Typhimurium. Int Immunopharmacol. 2011 Feb;11(2):149-56.
  24. Available at: https://www.cdc.gov/salmonella/index.html. Accessed June 15, 2021.
  25. Lam TK, Rotunno M, Lubin JH, et al. Dietary quercetin, quercetin-gene interaction, metabolic gene expression in lung tissue and lung cancer risk. Carcinogenesis. 2010 Apr;31(4):634-42.
  26. Theodoratou E, Kyle J, Cetnarskyj R, et al. Dietary flavonoids and the risk of colorectal cancer. Cancer Epidemiol Biomarkers Prev. 2007 Apr;16(4):684-93.
  27. Ekstrom AM, Serafini M, Nyren O, et al. Dietary quercetin intake and risk of gastric cancer: results from a population-based study in Sweden. Ann Oncol. 2011 Feb;22(2):438-43.
  28. Rich GT, Buchweitz M, Winterbone MS, et al. Towards an Understanding of the Low Bioavailability of Quercetin: A Study of Its Interaction with Intestinal Lipids. Nutrients. 2017 Feb 5;9(2).
  29. Supplier Internal Study. A randomized and crossover pharmacokinetic study of Quercetin 500mg., Quercetin Phytosome 500 mg. and Quercetin Phytosome 250 mg. administered in a single dose to healthy volunteers under fasting conditions. Data on File. 2017.
  30. Dancer RC, Parekh D, Lax S, et al. Vitamin D deficiency contributes directly to the acute respiratory distress syndrome (ARDS). Thorax. 2015 Jul;70(7):617-24.
  31. Teymoori-Rad M, Shokri F, Salimi V, et al. The interplay between vitamin D and viral infections. Rev Med Virol. 2019 Mar;29(2):e2032.
  32. Telcian AG, Zdrenghea MT, Edwards MR, et al. Vitamin D increases the antiviral activity of bronchial epithelial cells in vitro. Antiviral Res. 2017 Jan;137:93-101.
  33. Zdrenghea MT, Makrinioti H, Bagacean C, et al. Vitamin D modulation of innate immune responses to respiratory viral infections. Rev Med Virol. 2017 Jan;27(1).
  34. Tsujino I, Ushikoshi-Nakayama R, Yamazaki T, et al. Pulmonary activation of vitamin D3 and preventive effect against interstitial pneumonia. J Clin Biochem Nutr. 2019 Nov;65(3):245-51.
  35. 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. 2017 Feb 15;356:i6583.
  36. Bergman P, Lindh AU, Bjorkhem-Bergman L, et al. Vitamin D and Respiratory Tract Infections: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PLoS One. 2013;8(6):e65835.
  37. Meehan M, Penckofer S. The Role of Vitamin D in the Aging Adult. J Aging Gerontol. 2014 Dec;2(2):60-71.
  38. Barnett JB, Hamer DH, Meydani SN. Low zinc status: a new risk factor for pneumonia in the elderly? Nutr Rev. 2010 Jan;68(1):30-7.
  39. Available at: https://www.todaysgeriatricmedicine.com/news/ex_013113.shtml. Accessed June 18, 2021.
  40. Chasapis CT, Loutsidou AC, Spiliopoulou CA, et al. Zinc and human health: an update. Arch Toxicol. 2012 Apr;86(4):521-34.
  41. Haase H, Rink L. The immune system and the impact of zinc during aging. Immun Ageing. 2009 Jun 12;6:9.
  42. Pae M, Meydani SN, Wu D. The role of nutrition in enhancing immunity in aging. Aging Dis. 2012 Feb;3(1):91-129.
  43. Putics A, Vodros D, Malavolta M, et al. Zinc supplementation boosts the stress response in the elderly: Hsp70 status is linked to zinc availability in peripheral lymphocytes. Exp Gerontol. 2008 May;43(5):452-61.
  44. Available at: https://www.sciencedirect.com/topics/neuroscience/secretory-immunoglobulin. Accessed July 18, 2021.
  45. Salva S, Villena J, Alvarez S. Immunomodulatory activity of Lactobacillus rhamnosus strains isolated from goat milk: impact on intestinal and respiratory infections. Int J Food Microbiol. 2010 Jun 30;141(1-2):82-9.
  46. Reid G, Kort R, Alvarez S, et al. Expanding the reach of probiotics through social enterprises. Benef Microbes. 2018 Sep 18;9(5):707-15.
  47. Zelaya H, Tsukida K, Chiba E, et al. Immunobiotic lactobacilli reduce viral-associated pulmonary damage through the modulation of inflammation-coagulation interactions. Int Immunopharmacol. 2014 Mar;19(1):161-73.
  48. Villena J SS, Núñez M, Corzo J, Tolaba R, Faedda J, Font G, Alvarez S. Probiotics for everyone! The novel immunobiotic Lactobacillus rhamnosus CRL1505 and the beginning of social probiotic programs in Argentina. 2012.
  49. Available at: https://epicorimmune.com/our-origin/. Accessed June 18, 2021.
  50. Jensen GS, Patterson, K.M., Barnes, J., Schauss, A.G., Beaman, R., Reeves, S.G. and Robinson, L.E.,. A double-blind placebo-controlled, randomized pilot study: consumption of a high-metabolite immunogen from yeast culture has beneficial effects on erythrocyte health and mucosal immune protection in healthy subjects. The Open Nutrition Journal. 2008;2:pp.68-75.
  51. Jensen GS, Redman KA, Benson KF, et al. Antioxidant bioavailability and rapid immune-modulating effects after consumption of a single acute dose of a high-metabolite yeast immunogen: results of a placebo-controlled double-blinded crossover pilot study. J Med Food. 2011 Sep;14(9):1002-10.
  52. Moyad MA, Robinson LE, Kittelsrud JM, et al. Immunogenic yeast-based fermentation product reduces allergic rhinitis-induced nasal congestion: a randomized, double-blind, placebo-controlled trial. Adv Ther. 2009 Aug;26(8):795-804.
  53. Moyad MA, Robinson LE, Zawada ET, et al. Immunogenic yeast-based fermentate for cold/flu-like symptoms in nonvaccinated individuals. J Altern Complement Med. 2010 Feb;16(2):213-8.
  54. Moyad MA, Robinson LE, Zawada ET, Jr., et al. Effects of a modified yeast supplement on cold/flu symptoms. Urol Nurs. 2008 Feb;28(1):50-5.
  55. Jensen GS, Carter SG, Reeves SG, et al. Anti-inflammatory properties of a dried fermentate in vitro and in vivo. J Med Food. 2015 Mar;18(3):378-84.
  56. Available at: https://lpi.oregonstate.edu/mic/vitamins/vitamin-C. Accessed June 24, 2021.
  57. Heuser G, Vojdani A. Enhancement of natural killer cell activity and T and B cell function by buffered vitamin C in patients exposed to toxic chemicals: the role of protein kinase-C. Immunopharmacol Immunotoxicol. 1997 Aug;19(3):291-312.
  58. Ganesan S, Faris AN, Comstock AT, et al. Quercetin inhibits rhinovirus replication in vitro and in vivo. Antiviral Res. 2012 Jun;94(3):258-71.
  59. Mlcek J, Jurikova T, Skrovankova S, et al. Quercetin and Its Anti-Allergic Immune Response. Molecules. 2016 May 12;21(5).
  60. Zhu Y, Tchkonia T, Pirtskhalava T, et al. The Achilles’ heel of senescent cells: from transcriptome to senolytic drugs. Aging Cell. 2015 Aug;14(4):644-58.
  61. Aranow C. Vitamin D and the immune system. J Investig Med. 2011 Aug;59(6):881-6.
  62. Available at: https://lpi.oregonstate.edu/mic/minerals/zinc. Accessed June 24, 2021.