Respiratory immune health promotion through nutrition 

respiratory immune health through nutrition: Life Extension Europe

Recent findings on immune health promotion 

Immune health promotion through nutrition

Immune function naturally declines because of aging, resulting in a sharp fall which occurs after the age of 65-70 years. Experimental studies try for the restoration of stem cells in bone marrow, which is where all immune cells originate. (1, 2) The problem is that outside of research, therapies for renewal of stem cells are not yet available.  

However, there are multiple ways immunity may be strengthened through certain nutrients. Below is a summary of how readers use those multiple ways to support optimization of immune functionality.

  • Zinc: The mineral zinc has shown to help against several effects of viral respiratory issues, supporting a clearance away from airway surfaces, helping to prevent their entry into cells, and promoting the suppression of viral replication. An analysis of human studies showed that, when started after the first sign of cold symptoms, taking 80 mg to 92 mg of dissolve-in-the-mouth zinc in divided doses every few hours reduces the duration of symptoms by 25% to 44%. In most cases, the severity of symptoms was also reduced, by up to 40% to 50%. (3-5)
  • Elderberry: Clinical research suggests elderberry extract, rich in anti-inflammatory and antioxidant polyphenols, may reduce influenza symptoms and shorten duration of illness when started within 48 hours (about 2 days) of symptom onset. (6) Moreover, at higher doses, it prevented nearly 100% of the cells from becoming infected! (5)
  • Probiotics: More than 70% of your immune system is in your gut. With more than 100 trillion gut bacteria, outnumbering regular body cells 10 to 1, a healthy bacterial balance in your gut is essential to your health and immune system! Multiple randomized controlled trials and several meta-analyses have proposed that 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. The probiotic strain, Lactobacillus rhamnosus CRL1505, is shown to significantly boost 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. A trial of healthy male and female children found that, compared to placebo, consuming 100 million CFU (colony-forming units) of this probiotic strain five days weekly for six months resulted in: 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. (7,8) 
  • Lactoferrin (as apolactoferrin) is an immune modulator. Connected with enhancement of antimicrobial immune activity while reducing inflammation, it has shown signs of supporting a broad spectrum of activity against bacteria, fungi, protozoa, and viruses. (9,10) 
  • Vitamin D: A plethora of worldwide studies have found correlations between low vitamin D status and increased risk of respiratory viral infections and poor outcomes. (11) 
  • 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. (12-16) 
  • 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 (about the weight of a grain of table salt) of melatonin at bedtime for respiratory immune health support. (17, 8) 
  • N-acetylcysteine (NAC) helps inhibit cellular entry and replication of some respiratory viruses, supports assistance in clearing thickened mucous from the airways, and suppresses inflammatory signaling. (19) 
  • Vitamin C: is also known as ascorbic acid, and the strong link between this nutrient and immune health may result from its ability to stimulate the production and function of white blood cells — with a whole range of immune benefits following that! Vitamin C helps increase levels of antibody-producing cells (lymphocytes), boosts the function of infection-engulfing neutrophils, and helps NK (natural killer) cell activity. 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. (20-23) 
  • Selenium has been shown in preclinical studies to reduce infectivity, replication, and virulence of several respiratory viruses. (24-26) 
  • Licorice: Active constituents of licorice have demonstrated antiviral effects against viral causes of respiratory infection as well as other viruses. (27-29) 
  • 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. (30) 
  • Quercetin is a plant flavonoid that supports an immediate immune response to common colds and other upper respiratory infections. It's shown to reduce inflammatory immune cells, cut histamine levels, relax airway smooth muscle, inhibit replication and infectivity of cold-causing viruses, and reduce senescent cells and their pro-inflammatory signaling. (31-34) 
  • 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. (35-40)
  • 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. (41,42) 
  • 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. (43,44)
  • Echinacea is an immune-enhancing plant. Clinical studies have shown that compared to placebo, echinacea use can lead to an improvement in cold symptoms, fewer days with severe symptoms, and a reduction in cold incidence and severity, as well as reduce the risk of recurrent infections. (45,46) 
  • Beta-glucans: These prebiotic fibers may stimulate the body’s antimicrobial defense and prevent infection as well as decrease upper respiratory tract infection symptoms. (47)  
  • S. cerevisiae fermentate is a special yeast culture extract, and research shows that it can improve the immune response to environmental allergens and colds, as shown in controlled human studies. (8)
  • Botanical combo: Cistanche is an herb that primarily targets the adaptive immune system, the specialized branch of the system that allows for a stronger immune response tailored to specific pathogens while providing longer-lasting protection. Reishi, or Ganoderma lucidum, is a medicinal mushroom that has potent strengthening effects mainly on the innate immune system, the first-line component of the immune system that attacks foreign pathogens, including bacterial organisms, cells infected with viruses, and those transformed into malignant cells. Together, these bioactive agents, cistanche and reishi, work in a complementary fashion to rejuvenate both major arms of the aging immune system. (48)

How to test your immune system

Several lab tests have shone 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. (49,50)  And, paradoxically, lower levels of total WBCs or lymphocytes, the primary immune responder in viral infections, might be seen in severe infections. (51,52) 

Assessing the numbers of diverse 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. (54-55) 

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. On the other hand, regulatory T cells help ensure the immune system does not overreact and drive chronic inflammation or autoimmune diseases. (56)   

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. (57) Typically, a clinician will obtain a sample from the nose and/or throat to perform these types of tests. (58) 

 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

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 Natural Killer (NK) cell Function
Assesses functional (i.e., 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

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