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Immune Resilience: A Science-Backed Protocol for Preventive Maintenance

As cold and flu season approaches, immune health is top of mind for most patients, But rather than reacting to infection, a proactive protocol centered around diet, lifestyle and science-backed supplements focuses on supporting the body’s defenses and shoring up resilience.

“Reactive is the active process of responding to infection, either from insufficient preventive measures or overwhelming virulence that exceeds preventive efforts,” says Chris D. Meletis, Naturopathic Physician. “Proactive is the active process of preventive efforts through such measures as restful sleep, stress reduction, adequate nutrition and specific supplements for comprehensive immune-system maintenance.”

Here’s how a strategic protocol promotes robust and balanced immunity, reduces the risk of infection and protects patients all year long.1, 2, 3, 4

Maintaining immunity: evidence-based natural solutions.

Volumes of research confirm the efficacy of specific diet and lifestyle interventions for supporting immune health. The cornerstones:

  • A whole-foods, plant-rich diet with adequate protein and healthy fats supplies amino acids, fatty acids, fiber and essential nutrients, all vital for optimal immune system function. Studies also show plant-based diets maintain epithelial integrity, enhance microbial diversity and promote gut fitness—important for a robust immune response—and eating patterns that emphasize fiber have been shown to reduce gut inflammation and improve markers of gut health.5, 6, 7, 8, 9, 10, 11, 12
  • “Adequate sleep is essential for immune competence, and deep, restorative sleep supports immune memory, regulates inflammation and promotes overall resilience” says Meletis. Sleep deprivation has significant impacts on the immune system, impeding the production of antibodies, fueling inflammation, diminishing its ability to fight pathogens and leaving patients vulnerable to infection. Both acute and chronic sleep deprivation are linked with decreased activity of NK cells and higher levels of pro-inflammatory cytokines, and even one night of disrupted sleep alters immune function.13, 14, 15, 16, 17, 18, 19
  • “Chronic or intense stress is well-documented to impair immune function,” Meletis says. “Stress activates the HPA axis, leading to elevated cortisol levels, which suppress lymphocyte proliferation, NK cell activity, and antibody production. Prolonged stress also increases inflammation by altering the balance of cytokines, further compromising immune homeostasis.” Stress-management techniques like meditation and deep breathing practices are known to lower cortisol, dampen inflammation and enhance immune cell response and support overall immunity.20, 21, 22, 23, 24, 25, 26, 27, 28
  • A sedentary lifestyle compromises long-term immunity, and consistent physical activity is associated with immune competency and regulation. Exercise has been shown to promote recirculation of neutrophils, NK cells, immunoglobulins and other immune cells, modulate inflammation and improve immunity. Additional evidence suggests a physically active lifestyle lessens the risk of contracting a range of viral and bacterial infections. Regular exercise also decreases stress and encourages restful sleep, which in turn help maintain 29, 30, 31, 32, 33, 34, 35, 36

Strategic supplements for immune support.

In addition to dietary interventions and lifestyle modifications, a targeted supplement regimen is critical to shore up immunity and maintain resilience. “Diet and lifestyle are like the tiles on a floor,” Meletis says. “A multivitamin is the grout, filling in micronutrient gaps that that compromise host defenses and have not been covered by proactive, health-promoting efforts.”

A comprehensive multi that includes phytonutrients and plant-based antioxidants offers another layer of support. Lycopene, astaxanthin and resveratrol reduce inflammation and bolster immunity, and elderberry protects against pathogens and may shorten the duration and severity of colds and flu. And supplements with ingredients like melatonin and CBD can safely and effectively ease stress and improve sleep quality—crucial for immunity.37, 38, 39, 40, 41, 42, 43, 44, 45, 46

Beyond the basics, certain science-backed ingredients enhance immunity, not only minimizing infection but also maintaining long-term resilience. What the studies show:

  1. Astragalus. Used for thousands of years in traditional herb medicine, Astragalus membranaceus has been shown to alleviate inflammation, strengthen immunity and increase resistance to infection. Its bioactive compounds support immune cell response, regulate the production of cytokines and antibodies, and improve the function of NK cells, macrophages and other immune cells. Astragalus also has significant anti-inflammatory and antioxidant properties and positively impacts the gut microbiome—vital for immune health.47, 48, 49, 50, 51, 52, 53, 54
  2. NAC. N-acetyl-L-cysteine acts as a precursor to glutathione, a powerful antioxidant known to modulate inflammation and shield immune cells from oxidative damage. In studies, NAC supplementation influenced the function and activities of immune cells, reduced CRP levels and markers of inflammation, and enhanced immune response. NAC’s anti-mucolytic effects support respiratory health, lessening the severity of respiratory infections. Additional research suggests NAC’s ability to suppress viral replication, protect against infection and decrease frequency and severity of influenza-like symptoms, and emerging evidence hints at its therapeutic potential for COVID-19.55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65
  3. Olive leaf extract. Derived from the leaves of the olive tree, olive leaf extract contains antioxidant and anti-inflammatory constituents shown to support immunity. Oleuropein and different compounds in olive leaf directly impact immune system processes, increase the activity of immune cells, regulate the production and release of cytokines and enhance immunity. Studies also suggest olive leaf extract boosts immune response to a variety of pathogens, including influenza A and SARS-CoV-2, and recent research points to its promise in treating COVID-19 infection.66, 67, 68, 69, 70, 71, 72, 73, 74
  4. Berberine. Found in Indian barberry, goldenseal and other medicinal herbs, berberine has been shown to modulate inflammation, regulate immune cell activity and promote a balanced immune response. Research further demonstrates its positive effects on the microbiome and its ability to improve gut microbiota composition and diversity, essential for immune maintenance. Berberine’s antimicrobial properties protect against a number of pathogens, and some studies suggest berberine supplementation suppresses infection, inhibits viral replication and alleviates symptoms.75, 76, 77, 78, 79, 80, 81, 82, 83, 84
  5. Vitamin C. With its potent antioxidant, antimicrobial and anti-inflammatory activities, vitamin C plays a central role in innate and adaptive immunity. Vitamin C influences immune function through various mechanisms, regulating cytokine production, enhancing immune cell differentiation and proliferation and promoting epithelial integrity, and deficiencies are linked with impaired immunity and vulnerability to infection and disease. Studies also suggest vitamin C inhibits viral replication, improves symptoms, and may shorten the duration and severity of respiratory tract infections.85, 86, 87, 88, 89, 90, 91, 92, 93, 94
  6. Garlic extract. Garlic is rich in constituents known to modulate inflammation, minimize oxidative stress and support immunity. In clinical trials, garlic extract has been shown to stimulate the activity of NK cells, macrophages and lymphocytes, regulate cytokine production and increase the efficacy of endogenous antioxidants, including SOD. Allicin and other organosulfur compounds in garlic also have broad antimicrobial properties, with research demonstrating its antiviral effects against various pathogens and enhanced resistance to infections.95, 96, 97, 98, 99, 100, 101, 102
  7. Zinc. Critical for immune system development and function, zinc is involved in both innate and acquired immune responses, influencing multiple immune cells and inflammatory pathways. Deficiencies disrupt several immunological pathways, and chronic insufficiencies in zinc intake are implicated in impaired immunity and greater susceptibility to infection. Some studies highlight zinc’s ability to protect against a range of viruses, inhibit viral replication and reduce the severity and duration of respiratory tract infections.103, 104, 105, 106, 107, 108, 109, 110, 111
  8. Vitamin D. Vitamin D plays a key role in immune health, regulating inflammatory processes and cytokines, promoting the differentiation and activation of immune cells and improving epithelial barrier function. Deficiencies lead to immune system dysregulation, and studies link low vitamin D status with diminished resilience to viral infection and severe complications from illness. Conversely, adequate vitamin D levels are associated with less risk of viral and bacterial infections,  and new research suggests supplementation may protect against respiratory infections, decrease disease severity and mortality in COVID-19 and accelerate recovery.112, 113, 114, 115, 116, 117, 118, 119
  9. Citrus flavonoids. Quercetin, naringenin, naringin, hesperidin and other flavonoids found in citrus fruit have powerful antioxidant, anti-inflammatory and immunosupportive properties. In studies, citrus flavonoids have been shown to scavenge reactive oxygen species (ROS), reduce oxidative damage, enhance the activity and function of immune cells and modulate immune response. Citrus flavonoids appear to work synergistically with vitamin C, increasing its absorption and effectiveness. Additionally, emerging evidence points to therapeutic applications of flavonoids against viral infections, and hesperidin in particular is being investigated for its potential use in preventing and treating SARS-CoV-2 infection.120, 121, 122, 123, 124, 125, 126, 127, 128
  10. EpiCor. Produced from Saccharomyces cerevisiae yeast through a proprietary fermentation process, EpiCor is a concentrated source of bioactive compounds that regulate inflammation and promote immunity. Research shows EpiCor enhances NK cell activity and numbers, strengthens mucosal immunity and supports a balanced immune response. EpiCor is also rich in bioavailable antioxidants, and clinical trials demonstrate significant and rapid impacts on antioxidant levels after supplementation, associated with improves immunity. Other studies suggest EpiCor not only maintains healthy immunity but also decreases the incidence and duration of cold and flu symptoms, and may minimize susceptibility to viral infections.129, 130, 131, 132, 133, 134, 135, 136
  11. Hemp oil. Phytocannabinoids in hemp oil, including CBD and terpenes like beta-caryophyllene, are known to have potent antioxidant, anti-inflammatory and immune-modulating properties. CBD has been shown to regulate immune response and exhibit immunoprotective activities during viral infections, and a growing body of evidence highlights its possible applications for immune-related diseases. Beta-caryophyllene demonstrates similar effects, and studies points to its ability to impede viral replication and block viral entry into host cells. Recent research suggests a combination of terpenes and CBD may inhibit influenza and SARS-CoV-2 infection. Additionally, CBD eases stress and enhances sleep, important for immunity. Because it’s notoriously difficult to absorb, choose an advanced delivery system designed to improve bioavailability.137, 138, 139, 140, 141, 142, 143, 144, 145

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