by Melissa Blake, ND

A happy immune system is an important component of wellness. In light of the recent flu outbreak associated with the Coronavirus (COVID-19), the task associated with supporting immune health has become increasingly significant.

Avoiding illness is not always possible, but there are several steps healthcare providers can help patients put in place to support immune health and reduce the risk of getting sick, as well as minimize duration and complications if they do.

Please keep in mind, this article is not specific to COVID-19 but speaks to immune health in general. Specific to the COVID-19 outbreak, encourage patients to follow state/province/county guidelines and visit the national (CDC) and international (WHO) health organization sites for up-to-date notifications.

Key clinical takeaways

  1. Encourage a plant-based diet that includes a variety of vegetables and minimal sources of refined sugar.
  2. Provide patients with suggestions on sleep hygiene, including aiming for 7 or more hours of sleep per night, sleeping in a dark room, and setting a regular bedtime.
  3. Promote stress resilience with mindfulness-based practices.
  4. Tailor a supplement plan to address individual needs. Some nutrients that may support immune health include vitamins C and D, zinc, and probiotics.


Frequent handwashing

Hand hygiene is an effective way to prevent cases of influenza.1

The Centers for Disease Control (CDC) is a good resource that provides guidance for effective handwashing and the use of hand sanitizer. A recent study suggests soap and water are more effective against influenza A viruses than alcohol-based sanitizers;2 however, a combination of the two provides effectiveness and convenience.

Emphasize a whole-food diet

Eat more vegetables

A diet high in vegetables provides many health benefits and contributes to reduced rates of heart disease and cancer through antioxidant and anti-inflammatory actions.3

Vegetables provide fiber  which supports a healthy microbiome.4,5 They are also a source of phytonutrients, including flavonoids, carotenoids, ellagic acid, and phytoestrogens.5 These phytonutrients have numerous health benefits. Vegetables are also a source of essential micronutrients.5

Vegetables support immune health by helping to prevent deficiencies of essential vitamins and minerals, providing a source of antioxidants, and acting on the gut level to promote an optimal immune response.6,7

Both the diversity and the density of nutrients in vegetables play an important role in supporting immune health. Several studies show significant reduction in all-cause mortality associated with 3-5 servings of fruits and vegetables per day with the strongest benefit coming from raw vegetables.8-10

Reduce sugar intake

Excessive sugar consumption poses many health risks and contributes to inflammation,11 promotes diabetes in children and adults,12 and is a major cause of obesity.13

A study published several decades ago observed the impact of a 100 g dose of sugar on white blood cell (WBC) behavior in healthy participants.14 Researchers demonstrated a 50% decrease in neutrophils’ capacity to engulf bacteria in the 1-2 hours after the sugary drink was consumed.14 Sugar did not impact the number of white blood cells but rather their function.14

Further studies are needed to directly tie sugar consumption to an increased risk of infections; however, the lack of nutritional benefits along with contributing to chronic disease make sugar a habit healthcare providers should recommending ditching.

Reduce stress. Encourage rest.

We live in a sleep-deprived society. Data from the CDC indicated that 1 in 3 adults do not get the recommended minimum of 7 hours of sleep per night.15

Sleep loss has been linked to changes in cognitive health,16 poor mood,16 and an increase in cardiovascular disease.17 Lack of sleep has also been associated with an increased risk of obesity in children and adults.18

Sleep studies have shown an association with sleep deprivation and an increase in inflammatory markers, including C-reactive protein, as well as an increased susceptibility to the common cold and impaired responses to vaccinations.19

Encourage patients to make sleep a priority and practice good sleep hygiene, as both a preventative strategy and as part of a treatment plan.

Acute stress triggers an immune response, activating dendritic cells, neutrophils, macrophages, and lymphocytes as well as the release of cytokines.20 This makes good sense, particularly in response to a physical stress that requires wound healing or infection support.

Long-term, chronic stress, however, particularly of psychological origin, creates an increase in inflammation and altered cell function that ultimately lead to a dysregulated immune response.20,21

Strategies to support a healthy stress response, and reduce the negative impact on the immune system, include mindfulness practices,22 meditation,23 and yoga.24

Consider supporting immune health with bioactives

When used appropriately, nutritional supplements address common nutritional deficiencies and provide a targeted boost, particularly during cold and flu season.

Vitamin C

As it relates to immune function, studies have shown that vitamin C increases the action of natural killer cells, immune cells that are especially responsive to viruses.25 Vitamin C has also been shown to support optimal function of T and B cells,25 cell types that are part of an intricately orchestrated immune response involving memory and antibodies.25

Immune cells contain 10 to 100x more vitamin C than other human cells.25 This significantly higher concentration suggests vitamin C is extraordinarily important to the function of these immune cells.

A meta-analysis determined vitamin C supplementation in children shortened colds by 18% and also reduced severity.26


Even a mild zinc deficiency, which according to the World Health Organization is fairly common at approximately 31% worldwide, contributes to a weaker cell-mediated immune response.27

In populations at risk of zinc deficiency, preventive zinc supplementation has been shown to improve pregnancy outcomes, reduce death in children from infectious illnesses such as diarrhea and acute lower respiratory infections, lowers all-cause mortality, and increases linear growth and weight gain among infants and young children.28 Zinc supplementation during episodes of diarrhea reduced duration and severity.28

Studies using oral zinc supplementation repeatedly show a significant reduction in duration of infection, with most of the research exploring effects of zinc on the common cold.28

Vitamin D

Research demonstrates vitamin D modulates immune cells. Vitamin D has been demonstrated in macrophages to stimulate the production of antimicrobial peptides.29 Higher vitamin D exposure in vitro has been shown to upregulate regulatory T cell gene expression and influence cytokine production.30,31

Several studies have shown vitamin D plays a positive role in reducing respiratory infections and in prevention of influenza and influenza related complications.32 The impact appears to be more protective in patients who are vitamin D deficient.32


Disruptions in the gut microbiome have been implicated in everything from cognitive decline to allergies, and the research in this area continues to grow at a rapid pace.33-36

Changes in the GI and respiratory microbiome of adults have been implicated in the pathogenesis of chronic pulmonary diseases, including asthma and allergies.33 Dysbiosis has also been associated with psoriasis,34,35 psoriatic arthritis,35 and inflammatory bowel disease,36 suggesting a direct link between a balanced microbiome and the health of the GI and immune systems.

Although convincing evidence exists for their use, probiotic therapy is far from a one-size-fits-all approach. In fact, studies show clearly defined benefits are associated with specific strains of bacteria.

Studies using Lactobacillus acidophilus NCFM in children 3-5 years old reduced flu and cold symptoms, missed days of school related to illness, and antibiotic use.37

Evidence supports immune benefits of Bifidobacterium animalis subsp. lactis Bi-07 in elderly individuals by improving phagocytic activity of white blood cells, specifically monocytes and ganulocytes38 and that Lactobacillus plantarum HEAL9 demonstrates antiviral activity.39

To Find Out More About Immune Support for you and your family check out https://elitehealthinstitute.metagenics.com/ today to learn more.


Immune support is an important aspect of patient care to address year-round, but perhaps especially during cold and flu season. Lifestyle strategies, including proper handwashing and rest, as well as personalized supplement plans, offer safe and effective ways to support a healthy immune response and reduce the risk of acute illnesses.

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  3. Landete JM. Situations leading to reduced effectiveness of current hygiene against infection mucus from influenza virus-infection patients. Crit Rev Food Sci Nutr. 2013;53(7):706-721.
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  15. CDC Newsroom. https://www.cdc.gov/media/releases/2016/p0215-enough-sleep.html. Accessed March 13, 2020.
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  22. Elimimian E et al. Long-term effect of a nonrandomized psychosocial mindfulness-based intervention in Hispanic/Latina breast cancer survivors. Integr Cancer Ther. 2020;19:1534735419890682.
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  25. Mousavi S et al. Immunomodulatory and antimicrobial effects of vitamin C. Eur J Microbiol Immunol (Bp). 2019;9(3):73–79.
  26. Hemilä H et al. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013;1.
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  30. Lemire JM et al. 1,25-dihydroxyvitamin D3 suppresses human T helper/inducer lymphocyte activity in vitro. J Immunol.1985;134:3032–3035.
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  35. Scher J et al. Decreased bacterial diversity characterizes the altered gut microbiota in patients with psoriatic arthritis, resembling dysbiosis in inflammatory bowel disease. Arthritis Rheumatol. 2015;67(1):128-139.
  36. Takahashi K et al. Reduced abundance of butyrate-producing bacteria species in the fecal microbial community in Crohn’s disease. 2016;93(10):59-65.
  37. Leyer G et al. Probiotic effects on cold and influenza-like symptom incidence and duration in children. 2009;124(2):e172-e179.
  38. Maneerat S. Consumption of Bifidobacterium lactis Bi-07 by healthy elderly adults enhances phagocytic activity of monocytes and ganulocytes. J Nutr. Sci. 2014;2:e44.
  39. Sunmola A et al. Antiviral potentials of L. plantarum, L. amylovorus, and Enterococcus hirae against selected Enterovirus. Folia Microbiol (Praha). 2018;10:S12223.


Melissa Blake, ND is the Manager of Curriculum Development at Metagenics. Dr. Blake completed her pre-medical studies at Dalhousie University in Halifax, Nova Scotia and obtained her naturopathic medical training from the Canadian College of Naturopathic Medicine. Dr. Blake has over 10 years of clinical experience, specializing in the integrative and functional management of chronic diseases.


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