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The cold and flue season is almost upon us and I don't know about you but I do not want to get sick this winter! Having had RSV and Covid in 2021/2022, I'm even more determined to stay well. How about you?
To better understand how nutrition can help support our immune system, it's helpful to know a few things about how our immune system works so here's a quick summary:
Front Line Defense Our skin and mucous membranes serve as our first line of defense against foreign invaders by blocking pathogens from entering our body. Each of these mechanisms are designed to trap foreign material and wash or move it out of the body via coughing, sneezing, etc. and contain antimicrobials, acids, or enzymes to inhibit the growth of or destroy microorganisms.
Innate Response The innate immune response is the first response to an invading pathogen [virus, bacteria or other microorganism] or an injury. It involves release of cells [phagocytes, neutrophils, dendritic cells, mast cells, and eosinophils, among others] that ideally work in harmony to kill the invading pathogen, start repair, and signal the adaptive response.
Adaptive Response While the innate response occurs quickly, the adaptive immune response is more specialized and often more effective. It has the ability to specifically recognize a pathogen and ‘remember’ it if exposure were to occur again. An example of an adaptive response is immunity to the chickenpox virus once exposure has occurred.
Our gut also plays an important role in how our ability to fight off infections. Trillions of microbes inhabit the intestines and form a complex ecological community that influences both normal physiology and our susceptibility to disease. This is where nutrition comes in - providing our gut with the nutrients it needs to function at its best can support our body’s resilience against foreign invaders.
Let's Talk About Resilience
Immunological resilience allows our body to remain in a state of health or recover more quickly after exposure to a virus, detrimental bacteria, or toxin(s) occurs. Both our mental health and immune system are dependent on a strong and resilient microbiome. While building resilience doesn’t occur over the short-term, there are several nutrients that we should consume on a regular basis to support our overall immunological resilience. These nutrients include:
Adequate intake of vitamin D supports our innate immune system and works as a pro-hormone (which supports a healthy brain, metabolism, thyroid function, bone health, etc.). A recent study published in the British Medical Journal demonstrated that vitamin D supplementation decreased the risk of respiratory tract infections by 50% in people who were deficient in vitamin D and 10% in those with favorable vitamin D status.
Good food sources of vitamin D include wild salmon, dairy products, canned seafood or a supplement.*
Vitamin C Vitamin C is a powerful antioxidant. It supports both the innate and adaptive immune responses, and supports the adrenal glands through metabolism of cortisol (primary stress hormone) in the body to curb the stress response. Additionally, clinical research indicates low levels of vitamin C can lead to increased susceptibility to virus and infection and compromised immune health.
Good food sources of vitamin C include bell peppers, citrus fruits, broccoli, and berries. You can also take a supplement* but food is always best!
Zinc Zinc is also a powerful antioxidant and is required to activate certain immune cells. Zinc deficiency is associated with impaired immune function and increased risk of infections such as pneumonia in certain age groups.
Good food sources of zinc include beef, cashews, yogurt, and oysters. Supplements* are available too.
Polyphenols are a category of compounds naturally found in plant foods that help to neutralize harmful "free radicals" that can cause serious health conditions, such as heart disease, cancer, and diabetes. Polyphenols also help create a healthy gut microbiome, which in turn, supports our immune system (among other wonderful things that a healthy gut does for us).
Good sources of polyphenols include:
Black & green tea
A Harvard research study determined that consuming 5 cups per day increased the virus-fighting compound, interferon, by ten times! Enjoy 1-2 cups of organic green or black tea per day as a nourishing way to unwind and possibly support upper respiratory health
Ginger root Ginger has antimicrobial, anti-fungal, and antiviral properties. Ginger root supplementation has been shown to have anti-inflammatory and immune-supporting benefits. Grate ginger root into stir-fry, simmer slices in water to make tea, add to smoothies, and grate into soups.
Garlic contains alliin and allicin, which are compounds that have antimicrobial properties. While there isn’t strong evidence on the impact of garlic on the immune system, the studies that have been conducted suggest garlic may stimulate the immune system and have antimicrobial actions as well as lower inflammation, cholesterol, and blood pressure.
Be sure to discuss increased garlic use (or supplementation) with a healthcare practitioner if you are currently taking a blood thinner, insulin, or protease inhibitor.
Quercetin Quercetin, a polyphenol derived from plants, has been shown to reduce the incidence and severity of upper respiratory tract infection symptoms and may provide additional immune-supporting effects when combined with vitamin C. Food sources include: apples, berries, capers, grapes, onions, tomatoes and nuts/seeds.
Popcorn (of all things!)
It's true! Popcorn is actually an excellent source of polyphenols. One serving of popcorn contains up to 300 mg of polyphenols per serving compared to 160 for one serving of most fruits. Bet you didn't know that!
Fall is a good time to be proactive in fighting off colds and viruses (or at least minimizing their impact on you) by including more fruits, vegetables, and other high-antioxidant foods in your diet.
If you want to learn more about how nutrition can support your immune system, check out my 4-week self-paced course that includes recipes, cooking videos, and guidance on setting up a healthy kitchen, Nutrition for Optimal Immunity Here's a sample cooking video from the course, with my colleague Jeanne Petrucci, MS RD, demonstrating how to make Avocado Lime Salmon!