A huge part of our immune resilience comes down to the inputs we give our immune system – the food we eat and the lifestyle choices we make. These choices can either help build a strong and balanced defense system or it can weaken those defenses, encouraging them to flop, misfire or overshoot. If you’re not sure what’s in your immune support arsenal, read on to find out what you can be doing to keep your critical defense system doing its best job for you.
Here at the DrKF clinic we continue to think about COVID-19, but we’re also now thinking about all the regular winter germs we’re starting to face again. All those bugs that thrive in the dryer, colder weather and present a double risk for getting sick, losing work or school time, or worse. And we’re thinking about the long-tail of COVID-19 that we’re just starting to get good scientific data on. Those effects of infections that can have long-lasting impacts on our everyday quality of life and productivity, for months if not years.
In this article, you’ll find the top five foundational nutritional and lifestyle strategies you can use to support your immune system for both acute COVID-19, the seasonal cold and flu season, and the long-tail of the various bugs (including COVID-19) you might encounter.
These strategies are for anyone who wants to:
- Support their immune system’s ability to fight off winter germs and COVID
- Reduce risk factors associated with worse COVID outcomes and long COVID
5 Steps for Supporting your Immune Resilience
1. Diet. When we eat food, we are influencing a complex community of gut microbes, which in turn influences the body’s immune response. In addition, nutrient deficiencies due to poor-quality food, inadequate nutrient intake, altered gut health, and other factors increase disease susceptibility. More than 70% of the immune system is located in the gut. When the gut is compromised, it becomes hyperpermeable (also known as “leaky gut”) and can allow undigested food particles and toxins into the bloodstream, which can lead to immune dysregulation and chronic inflammation. Our blog on leaky gut dives deeper into this topic if you’d like to learn more. By focusing on dietary and lifestyle choices that support gut health, you will also strengthen the immune system.
Things you can start working on include eating a diverse diet that is high in colorful plant foods. In addition to the other foods you eat, these will boost your nutrient, antioxidant and fiber intake. Limit the worst immune-offenders as much as possible – high sugar foods, refined carbohydrates like white rice, white bread, and white pasta, and highly processed foods that contain poor-quality ingredients and artificial additives.
- Key nutrients that support the immune system include vitamins A, B, C, D, K, and E, zinc, selenium, pre-and probiotics, omega-3 fatty acids, and polyphenols such as quercetin, curcumin, and rosmarinic acid.
- Vitamin A: This vitamin supports the production of secretory immunoglobulin A (IgA), a protective antibody found in our saliva, in our airways, and in our digestive tract that is a key first-line defense against viruses. Vitamin A is also needed to support the high cell turnover in the gut where cells are constantly regenerated to keep the barrier healthy. Food sources of Vitamin A and provitamin A (beta-carotene) include liver, sweet potato, carrot, winter squashes, and dark leafy greens.
- B vitamins: Folate, vitamin B6 and vitamin B12 are involved in energy metabolism, DNA methylation, and regulating the immune response. Folate food sources include liver, beans, leafy green vegetables (like cabbage, broccoli, kale, and spinach), and capers. Vitamin B6 food sources include fish, meats, liver, eggs, spinach, sweet potatoes, bananas, potatoes, and avocados. Vitamin B12 is found only in animal foods including in meats, poultry, fish, shellfish, eggs, and dairy products.
- Vitamin C: This antioxidant boosts white blood cell and antibody production, increasing the body’s ability to fight infections. Vitamin C also helps to protect the body from collateral damage caused when our immune system goes into attack mode. Diets high in fruits and vegetables have lots of vitamin C, but especially good sources are kiwi fruit, guava, peppers, and citrus fruits.
- Vitamin D: This “sunshine” vitamin decreases unruly inflammation, stimulates our cells’ own antimicrobial activity in our mouth, airways and digestive tract, and supports a healthy gut microbiome. Food isn’t considered a good source of Vitamin D, although it is found in very small amounts in beef liver, cod liver oil, egg yolks, fish, mushrooms, poultry and meats. Safe exposure to natural sunlight is the best way to boost your vitamin D levels and supplementation is usually needed in people with reduced sun exposure, darker skin, during darker winter months, or for those living in higher latitudes.
- Vitamin K: This vitamin supports the immune system by reducing aberrant inflammation too. Keeping inflammation levels in check is important to help your immune system defeat germs without going overboard (which can manifest as allergies, asthma, autoimmunity, and can even dangerously escalate symptoms of an infection). Foods rich in vitamin K include dark green vegetables, eggs, and meat.
- Vitamin E: This antioxidant protects immune cell membranes from oxidative damage and increases our production of antibodies and natural killer cells, both of which protect against infections. Vitamin E is fat soluble and so found in several foods with higher fat content such as almonds, avocado, brazil nuts, cashews, hazelnuts, herring, olive oil, pine nuts, and sunflower seeds. It is also found in vegetables such as asparagus, broccoli, leafy greens, carrots, and tomatoes.
- Zinc: This antioxidant helps prevent leaky gut, reduces oxidative stress, and supports the development and function of T regulatory cells, neutrophils and natural killer cells, which are white blood cells that help the body respond to infections. It also has direct antimicrobial properties – a sugar-free zinc lozenge can be a good first strategy against the beginnings of a sore throat, for instance. Oysters are the highest zinc food of all, providing an adult’s entire daily zinc recommendation in just 2 individual oysters. Other good sources are seeds, nuts, meats, and mushrooms.
- Selenium: This antioxidant protects immune cells from oxidative stress and stimulates the immune system by increasing T cells and natural killer cells, which assist the body’s immediate immune response. Brazil nuts are particularly high in selenium, with just 1 nut providing the recommended daily amount. Fish, eggs, meat, and sunflower seeds are additional sources of selenium.
- Probiotics/prebiotics: Probiotics such as Lactobacillus, Bifidobacterium, and Saccharomyces are friendly bacteria that help regulate immune function by inhibiting the growth of pathogens, reducing inflammation, keeping our immune system alert but not over-responsive, and even training our immune cells in how to behave. Fermented foods such as sauerkraut, kimchi, and lacto-fermented vegetables are excellent sources of probiotics. Prebiotics are non-digestible fibers that feed our resident beneficial gut bacteria, thus strengthening the gut lining and immune system. Prebiotic foods include leeks, garlic, onions, Jerusalem artichokes, and chicory root.
- Omega-3 fatty acids: These long-chain fatty acids help regulate the immune system by increasing good gut bacteria, increasing B cells, a type of white blood cell that produces our antibodies, and reducing inflammation. Omega-3-rich foods include cold water fish (sardines, salmon, anchovies, mackerel, herring), flax seed, chia seeds, and dark leafy greens.
- Quercetin: This antioxidant reduces inflammation and inhibits viral replication. Quercetin can be found in capers, dark leafy greens, onions, apples, other colorful vegetables and fruits, and teas.
- Curcumin: This turmeric-derived compound has antiviral, antibacterial and anti-inflammatory effects and plays a role in regulating the immune system. Mixing turmeric with black pepper, which contains a compound called piperine, as well as some fat, can increase absorption by 2000 percent. Check out our Golden Turmeric Milk recipe for a delicious way to enjoy this powerful nutrient.
- Rosmarinic acid: This antioxidant compound has anti-inflammatory, antibacterial, and antiviral qualities and helps regulate the immune system. It can be found in herbs including rosemary, peppermint, spearmint, thyme, sage, oregano, basil, and lemon balm.
Many of these foods and nutrients interact synergistically to support the immune system – this is why we emphasize whole foods where possible as a primary source for obtaining the nutrients needed to support the immune system.
In addition to prioritizing healthy dietary choices, the following lifestyle habits help build a strong and balanced defense system:
2. Stress Resilience: Chronic stress has a profound negative impact on the immune system and research suggests nearly 70% of Americans are experiencing increased stress as a result of the pandemic. Chronic stress results in an increase in adrenaline, noradrenaline and cortisol, which suppresses the immune system via a decreased production of T cells and antibodies. It’s the same reason that cortisol’s cousin, cortisone, is used in medicine to suppress immune responses. This makes stress management an important foundational step in supporting immune health and can be addressed in a variety of creative ways. Some of our favorite options to reduce stress include:
- Mindfulness meditation, which emphasizes being present in the moment. Research shows this technique can reduce inflammation, support the immune system by increasing white blood cells, and increase positive emotions. This website offers a nice overview of how to use this technique. You can also find a variety of great free apps and videos online with guided meditations.
- Breathing techniques lower cortisol levels, blood pressure, and help decrease anxiety. Simply paying attention to your breathing throughout the day can help you respond to stress with mindful breathing. Here are three breathing exercises to try.
- Gratitude journaling refocuses your mind from negative thoughts and emotions to reflecting on things you are grateful for. We suggest writing down 3-5 things you are grateful for every day – and sharing it with someone else, because just the act of sharing your gratitude increases positive emotions in both yourself and others.
- Tapping, also known as “Emotional Freedom Technique”, has been shown to increase secretory IgA (a key first-line defense against viruses), lower cortisol and decrease anxiety, stress and depression. Check out our podcast about tapping here.
- Community support, which can be pursued with creativity during the pandemic, such as scheduling a weekly date with a friend, sharing your daily gratitude journal with your spouse, or finding a support group. Research shows that social isolation can depress the immune system via an increase in cortisol and inflammation.
- Spending time in nature, which helps reduce stress and boosts immune functioning by decreasing inflammation and increasing white blood cell production. It can be as simple as spending time in a small backyard garden or walking in a park while enjoying the sights, smells, and sounds of nature.
3. Good sleep is associated with a reduced risk of infections, reduced inflammation and an increase in T helper cells, which support antiviral immune response. Sleep quality is affected by factors such as chronic stress, increased screen-time, and lack of daily movement. Tips to improve sleep include maintaining a consistent sleep schedule, consistent movement or exercise, avoiding caffeine in the afternoon, reducing exposure to artificial light, and any of the stress management exercises above.
4. Moderate exercise reduces stress, boosts white blood cells and can decrease inflammation. We suggest finding an activity that you enjoy, such as dancing, walking, yoga, bicycling, swimming, kick boxing, etc and incorporate it into your weekly routine, perhaps even combining it with social interaction.
A word of caution – high intensity exercise can temporarily increase inflammation and even suppress immune responses. It’s best to build up your exercise regime gradually and aim to reach a moderate 60-80 of your maximum potential exertion.
5. Clean living: Environmental exposures including heavy metals, pesticides, and endocrine disruptors such as polychlorinated biphenyls (PCBs), phthalates, and bisphenol A (BPA) alter immune system functioning by increasing inflammation and decreasing important T regulatory cells, which help the body respond to infections. These chemicals are commonly found in plastic containers, canned foods, detergents, toys, personal care products, and cosmetics. A simple place to start reducing toxic exposure is to eat local organic foods, reduce processed food intake, filter your water and indoor air, and use less-toxic food storage and personal care products. The Environmental Working Group is a great resource for learning more about environmental pollutants and ways to reduce exposure.
In light of the challenges we face in this COVID-19 era, and as we head into the winter months, each of us have an opportunity, maybe even a calling, to become stronger, healthier, and more resilient. Let us know what you’re doing to support immune resilience in the comments below.
This article was co-authored by Romilly Hodges, MS CNS CN IFMCP CKNS and Josette Herdell, MS CNS CN LDN.