By Dr. Shawna Darou, ND
There is so much talk right now about the immune system, and I wanted to share some strategies you can take this fall with the change of seasons for a healthy immune system. I am finding lots of mis-information online right now, so I have put together a short list of evidence-based strategies for your immune system. If you are choosing to take lots of vitamins and supplements, please check first! For example high doses of vitamin D or vitamin A can create toxicity; high doses of zinc can offset your zinc /copper balance, and many nutrients should be tested before supplemented. I am all for correct supplementation, but remember that there’s more to your immune system functioning well than supplements alone. Here is a list of factors to consider right now.
(1) Optimize Vitamin D Levels
With the change of seasons, vitamin D levels tend to drop and for some people this happens very rapidly. The majority of observational studies show that low levels of vitamin D increase the risk of respiratory viral infections. Vitamin D has many immunomodulatory properties, and signals immune cells such as macrophages and dendritic cells involved in pathogen recognition. (1,2,3)
The best practice is to test your vitamin D levels with a blood test before supplementing, because absorption rates vary tremendously from person to person. Vitamin D supplements are essential for anyone living in Ontario through the fall and winter months, because at our latitude we cannot absorb sufficient vitamin D from the sun from end of October to end of April. High doses of vitamin D should only be taken with medical supervision, as vitamin D toxicity can cause issues with hypercalcia and kidney function.
(2) Lower stress and anxiety
Many of us have been going through an extended period of stress and anxiety over the past 6 months, and yet this is important to address for your immune function.
One mechanism involved is that chronic psychological stress is associated with the body losing its ability to regulate an inflammatory response. Studies find that people suffering from more psychological stress were more susceptible to developing common colds. (4) With a cold, symptoms are not actually caused by the virus, they are a consequence of the inflammatory effect of the body fighting the infection. The more inflammation, the more symptoms experienced. (5) Stress can also dysregulate the humoral and cellular immune responses to pathogens, increasing the risk of infectious illness including influenza. (6)
If you are struggling with an increased stress-load and higher anxiety, prioritize support for your mental health right now, and look for resources to reduce your overall stress levels. Sometimes simply recognizing the layers of stress you have right now can help you to identify which ones you can begin to change right way. Think of stresses as stacking up, reaching a threshold where you get symptoms. Removing certain layers is easier than others, for example eating regular meals, going to bed early, and starting a night-time meditation practice can be a great start.
(3) Exercise regularly, but don’t overtrain
Prolonged, intense exercise causes immuno-suppression, while moderate intensity exercise improves immune function and potentially reduces risk and severity of respiratory viral infection. (7)
There is a J-shaped curve showing the relationship between exercise and upper respiratory tract infections. Infection risk is reduced 40-50% with moderate exercise, compared to a sedentary person; but infections rates can increase 2-6 fold with heavy exertion. Sedentary is defined as 1 or less days of exercise per week; moderate exercise is 5 or more days of 20-60 minutes or aerobic activity; and heavy exertion is high exercise training workloads or competitive events. (8)
The mechanism is interesting: while you exercise, the interchange of innate immune system cells and components of lymphoid tissue is stimulated. This improves immunosurveillance against pathogens and cancer cells, and decreases systemic inflammation. (9)
Another fascinating fact about exercise is that regular exercise delays the onset of ‘immunosenescence’, which is the immune dysregulation and decline the occurs with aging. (9)
If you’re not regularly exercising, now is the time to start, and to especially develop some consistent habits before the colder weather comes, and motivation tends to drop. Again, you’re aiming for moderate cardiovascular activity for 20-60 minutes five times per week to have the best impact on your immune system. If you’re not already fit however, please start more slowly!
(4) Reverse insulin resistance
Another important step for an optimally functioning immune system is to address insulin resistance and pre-diabetes. We know that insulin resistance creates an overall inflammatory state in the body, partly through action of T-cells in abdominal fat that create a pro-inflammatory state. Research shows that people with insulin resistance and pre-diabetes (as well as obesity and type 2 diabetes) have a poorer immune response to infection and pathogens. (10) Another study showed that those with insulin-resistance had a slower and more deficient immune response to infection. (11)
I have written several articles about insulin-resistance, and how to reverse it. This includes a nutrition plan with reduced carbohydrates, higher fiber and protein intake, getting sufficient sleep, and regular exercise. Remember that insulin resistance and pre-diabetes are reversible!
(5) Reduce alcohol intake
As a way of coping with increased stress levels and social isolation, it has been extremely common to hear about higher than usual alcohol intake. This is concerning when the pattern is lasting over months now, as it can have detrimental effects on hormone balance, mood, sleep, fertility and blood sugar regulation.
Research shows that high amounts of alcohol, which is classified as 14 drinks per week or more than 5-6 drinks at a time, directly suppresses the immune system and increases the risk of infectious disease. Chronic alcohol intake interferes with the normal functioning of both the cell-mediated and humeral immune responses, which increases susceptibility to viral and bacterial infections, and overall inflammation. In addition, chronic alcohol consumption can lead to more severe lung conditions such as pneumonia. (12,13)
If you have found yourself in the habit of of daily drinking, or having more than 3-4 drinks per week, perhaps this will be the motivation to reduce your intake. Start by limiting to just weekends, and then reduce your intake overall. You will notice a positive impact – especially on your mood and sleep.
(6) Improve your sleep
As you may expect or recognize in yourself, chronic sleep-deprivation has a big impact on your health. It impacts your blood sugar metabolism, food cravings and appetite, memory and mood, and it also has a big impact on how your immune system functions.
Chronic sleep deprivation is simply a state of chronic stress. We require sleep to down-regulate the two stress systems: the hypothalamus-pituitary-adrenal (HPA) axis, and the sympathetic nervous system (SNS). Deep sleep results in a drop in cortisol, epinephrine and norepinephrine levels. Without this reduction in the stress response, the body is in a state of persistent low-grade inflammation, which increases susceptibility to infections and a reduced immune response overall. (14,15,16,17)
If you have been struggling with sleep, first start with the basics of sleep hygiene: getting to bed at a consistent time, winding down before sleep, avoiding blue-light screens in the last hour before bedtime, and creating a cool, dark sleeping environment. If your sleep struggles are more rooted in anxiety or hormones, addressing these issues first can help.
If you would like help supporting your immune system this fall, please ask at your next appointment. We can review all of the factors above, test your vitamin D levels (highly recommended!!), and create a personalized plan.
- Bryson K., Nash A, Noravl M. (2014). Does vitamin D protect against respiratory viral infections? Epidemiology and Infection, 142(9), 1789-1801.
- Greiller CL, Martineau AR. Modulation of the immune response to respiratory viruses by vitamin D. Nutrients. 2015 May 29;7(6):4240-70.
- White JH. Regulation of intracrine production of 1,25-dihydroxyvitamin D and its role in innate immune defense against infection. Arch Biochem Biophys. 2012 Jul 1;523(1):58-63.
- Cohen S, Tyrrell DA, Smith AP (1991) Psychological stress and susceptibility to the common cold. N Engl J Med 325:606–612
- Cohen S, Janicki-Deverts D, Doyle WJ, et al. Chronic stress, glucocorticoid receptor resistance, inflammation, and disease risk. PNAS, April 2, 2012
- Glaser R, Kiecolt-Glaser JK (2005) Stress-induced immune dysfunction: implications for health. Nat Rev Immunol 5:243–251
- Martin SA, Pence BD, Woods JA. Exercise and respiratory tract viral infections. Exerc Sport Sci Rev. 2009;37(4):157-164.
- Nieman, D.C. 1994. b. Exercise, upper respiratory tract infection, and the immune system. Med. Sci. Sports Exerc. 26:128-139.
- Nieman DC, Wentz LM. The compelling link between physical activity and the body’s defence system. Journal of Sport nd Health Science 8 (2019) 201-217.
- Tsai S, Clemente-Casares X, Zhou AC, et al. Insulin receptor-mediated stimulation boosts t cell immunity during inflammation and infection. Cell Metabolism. 2018: 28(6): 922-934.
- Zhou, W., Sailani, M.R., Contrepois, K. et al. Longitudinal multi-omics of host–microbe dynamics in prediabetes. Nature 569, 663–671 (2019).
- Sarkar D, Jung MK, Wang HJ. Alcohol and the Immune System. Alcohol Res. 2015;37(2):153-155.
- Szabo G, Saha B. Alcohol’s Effect on Host Defense. Alcohol Res. 2015;37(2):159-170.
- Besedovsky L, Lange T, Born J. Sleep and immune function. Pflugers Arch. 2012;463(1):121-137.
- Dhabhar FS. Enhancing versus suppressive effects of stress on immune function: implications for immunoprotection and immunopathology. Neuroimmunomodulation. 2009;16:300–317.
- McEwen BS. Sleep deprivation as a neurobiologic and physiologic stressor: allostasis and allostatic load. Metabolism. 2006;55:S20–S23.
- Meerlo P, Sgoifo A, Suchecki D. Restricted and disrupted sleep: effects on autonomic function, neuroendocrine stress systems and stress responsivity. Sleep Med Rev. 2008;12:197–210.