Each year as the weather begins to cool down and the days become shorter, grocery stores become covered in ads for free flu shots as the topic of “boosting your immunity” starts to overwhelm social media and our everyday conversations. The pandemic has only emphasized just how essential not only protecting but strengthening our immune systems is no matter what time of year it may be.
While your first step in defense should start with a flu vaccination, it should never be the last. It’s crucial to consciously pursue a lifestyle that supports our immune system, which doesn't have to be as complicated as we think it may be.
Our entire body benefits from healthy dietary habits, but we can focus on specific micronutrients proven to particularly support immune functions as our risks increase seasonally. It’s important to remember that no singular food or supplement can be relied on to bolster immune activity. Stanford School of Medicine nutrition scientist Christopher Gardner explains that “it is the interplay of harmonious interactions between the various micronutrients,” that take place during digestion and internal synthesis that enable a “robust cellular immune response” and not just isolated nutrients in themselves.
The key takeaway to consider here is how you can incorporate as many whole, nutrient-dense foods into your diet as possible by eating a highly diverse array of fruits, vegetables, whole grains, legumes, healthy fats, and lean proteins– following a Mediterranean-style diet is a great place to start.
What is The Immune System?
The immune system is comprised of a complex network of cells, organs, and tissues that interact to defend the body against antigens, which are harmful substances like bacteria, toxins, and viruses we come in contact with constantly throughout the day. Not only does the immune system act against external antigens, but it also works internally to destroy abnormal cells with damaged DNA that can eventually divide uncontrollably and cause cancer.
The two subsystems, the Innate and the Adaptive, come together to perform the entire span of immune responses that the body requires.
The Innate system is the one we are born with, often cited as our first line of defense against pathogens. It includes the external barriers like our skin and mucous membranes that prevent harmful substances from entering the body, in addition to white blood cells like the Natural Killer (NK) cells. The Innate system is our generalized defense mechanism meaning anything identified as foreign or harmful is immediately targeted.
When our innate immune system comes into contact with a harmful substance it cannot control on its own, our Adaptive immune system is activated to specifically target the pathogen. The adaptive system is developed over time through repeated exposure to pathogens, which allows the system to learn and recognize the specific pathogen. The adaptive immune system creates antibodies, which you can think of as a name tag for the immune system, produced in response to and counteracting a specific antigen. These antibodies tell the adaptive immune system to produce the proper B cells and T cells necessary to fight the pathogen recognized.
The Immune Response and Inflammation
When our immune system detects a pathogen or a physical injury, it works immediately by initiating an inflammatory response. This acute state of inflammation triggers white blood cells to flood the problem area and sequester any pathogens, preventing them from spreading. When everything goes according to plan, the immune system knows when to resume normal, uninflamed programming by reducing the amount of cells at the site when the threat is reduced or the wound heals.
However, this "good" inflammation can quickly become harmful and go on longer than necessary, otherwise known as chronic inflammation. When the body continues sending out increased levels of inflammatory cells even though there is no longer a threat, the excess immune cells start attacking healthy cells, damaging tissues and organs. Chronic inflammation is often invisible, and you may not realize that your body is living in a constant state of high stress until mild symptoms like body aches, digestive discomfort, fatigue, anxiety, and consistent infections or colds become unavoidable. Chronic inflammation can have a number of causes, from autoimmune disorders like arthritis, obesity, smoking, and persistent exposure to chemicals and oxidative stress.
Keep your immune system strong and regulated by incorporating the following nutrients and minerals into your diet daily.
The Micronutrients You Need to Support Your Immune System This Winter
Polyphenols and other Antioxidants
How they work + what it does for the immune system:
Polyphenols, naturally occurring phytochemicals found largely in the fruits and vegetables act as our main source of dietary antioxidants. One of the most important polyphenolic structures identified in nature is oleocanthal. It is found only in extra virgin olive oil, and known to be one of the most potent immune-supporting anti-inflammatory agents within the superfood. Polyphenols like oleocanthal protect our immune systems by negating the effects of the oxidative stress caused by the harmful free-radicals we are constantly encountering in our environments. Polyphenols also support healthy immune systems by regulating the adaptive immune system's response to pathogens through the inhibition of the overproduction pro-inflammatory enzymes our body produces when chronically inflamed.
Whole- foods sources high in polyphenols:
- Extra Virgin Olive Oil (only source of oleocanthal)
- Spices (curcumin for example)
- Flax Seeds
- Green Tea
How it works + what it does for the immune system:
Vitamin D is a nutrient we derive from our diets and produce ourselves through the absorption of the UV rays we encounter from the sun. Vitamin D is a fundamental component of bone health as without it our bodies are incapable of absorbing calcium, the primary building block of our bones. When it comes to the immune system, Vitamin D is known to initiate the body’s immune response and enhance the function of the T, B, and macrophage immune cells that protect your body against pathogens.
Whole- foods sources high in Vitamin D:
- Fatty fish
- Egg yolks
- Cod-liver oil
Ways to incorporate Vitamin D into your diet:
- Aim to enjoy fatty fish like salmon as the main protein on your dinner plate at least once a week.
- Canned sardines are a hugely underrated way to incorporate fatty fish into your diet, and can make a great lunch on the go when paired with a bead of leafy greens, and hard-boiled eggs, all dressed with an olive oil vinaigrette. Think of it as a new take on a Nicoise salad.
How it works + what it does for the immune system:
This fat-soluble, essential vitamin primarily functions as an antioxidant within our bodies, working to protect cells from the damage caused by free radicals. Vitamin E has been shown to increase the production of the white blood cell known as T Cells. T cells are specifically designed to fight infections they have not yet encountered, playing a central role in our adaptive immune system in building immunological memory.
- Olive oil
- Nuts like peanuts, hazelnuts, and almonds
- Seeds like sunflower and pumpkin
- wheat germ
- Beet greens, collard greens, spinach
Ways to incorporate Vitamin E into your diet
- One tablespoon of olive oil contains approximately 1.9 mg of vitamin E, roughly 13% of the DRA for adults, so just simply cooking with this powerfully nutritious ingredient can ensure proper vitamin E intake on a daily basis.
- Make a superfood trail mix with sunflower seeds, almonds, and dried mango for an energizing vitamin E-rich snack.
How it works + what it does for the immune system
The mineral zinc is utilized by almost 100 different enzymes in the body to carry out many different critical chemical reactions involving DNA creation, cellular growth, and healing damaged tissues, all of which support a healthy immune system. Because of zinc’s role in facilitating the growth of properly functioning immune cells multiplication, it is of particular importance that we get adequate amounts during Because zinc supports the growth of normal functioning of immune cells like lymphocytes, lack of proper levels of zinc in our bodies can leave us vulnerable to viruses and bacteria from a slow down in the activity of the immune cells that fight them.
Whole-food sources high in Zinc:
- Seafood like oysters, crab, and lobster
- Lean proteins like chicken and beef
- Nuts and seeds
- Whole grains
Ways to incorporate them into your diet:
- One of our favorite plant-based ways to get in our zinc is by sprinkling a handful of raw pumpkin seeds (also known as pepitas) on top of oatmeal, salads, or yogurt.
How it works + what it does for the immune system:
This essential vitamin needs to come from our diets as we don’t produce it ourselves, and as a potent antioxidant, it works to actively ward off oxidative stress from harmful free radicals and pathogens. Vitamin C is also a co-factor critical for the enzymes that synthesize collagen, the primary component of the dermis. Thus, vitamin C works to bolster our skin, the first line of defense against external pathogens through enhanced collagen production.
Whole- foods sources high in vitamin C:
- Citrus fruits
- Bell peppers
- Cruciferous vegetables
- White potatoes
Ways to incorporate Vitamin C into your diet:
- Squeeze a fresh lemon into your water to sip on throughout the day. Or, make it an enjoyable step in your morning routine by sipping hot water with your favorite citrus. Blood orange with a dash of warming spices like cinnamon is one of our current favorite combinations.
Naturally Antibacterial Foods
Garlic contains the amino acid alliin, which when crushed is converted into the compound allicin thanks to the presence of the enzyme allinanase. Allicinn acts as an antimicrobial by inhibiting viral and bacterial growth. It’s highly unstable thus it’s apparent you consume it raw and crushed or sliced to derive the benefits.
Unfiltered, raw honey inhibits the growth of bacteria and viruses in multiple ways due to its unique phytochemical makeup. First off, honey’s low, acidic pH levels coupled with its high sugar content makes it hygroscopic, which means it absorbs excess moisture in the environment and subsequently dehydrates bacteria, preventing microbial growth. When bees harvest nectar, they also take with them the enzyme glucose oxidase, which breaks down the sugars in honey resulting in a natural production of hydrogen peroxide– yep, the same stuff in the bottle you may have tucked away in your medicine cabinet from the drug store.
- Bizerra, F. C., Da Silva, P. I., & Hayashi, M. A. F. (2012, November 22). Exploring the antibacterial properties of honey and its potential. Frontiers in microbiology. Retrieved November 16, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3504486/
- Bruso, J. (2018, November 21). Does olive oil contain vitamin E? Healthy Eating | SF Gate. Retrieved November 16, 2022, from https://healthyeating.sfgate.com/olive-oil-contain-vitamin-e-5571.html
- Hussain, T., Tan, B., Yin, Y., Blachier, F., Tossou, M. C. B., & Rahu, N. (2016). Oxidative stress and inflammation: What polyphenols can do for us? Oxidative medicine and cellular longevity. Retrieved November 16, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5055983/
- LaMotte, S. (2021, November 16). How to use food to boost your immune system. CNN. Retrieved November 16, 2022, from https://www.cnn.com/2021/11/16/health/food-boost-immune-system-wellness/index.html
- Levy, J. (2022, February 21). The healthiest part of garlic? Dr. Axe. Retrieved November 16, 2022, from https://draxe.com/nutrition/allicin/
- Marketing, M. (2022, August 2). Different types of T cells and their functions. Akadeum Life Sciences. Retrieved November 16, 2022, from https://www.akadeum.com/blog/different-types-of-t-cells/
- Nutrition and Immunity. Hsph.harvard.edu. (n.d.). Retrieved November 16, 2022, from https://www.hsph.harvard.edu/nutritionsource/nutrition-and-immunity/
- Santos-Longhurst, A. (2021, August 20). What is chronic inflammation (and how to treat it). Healthline. Retrieved November 16, 2022, from https://www.healthline.com/health/chronic-inflammation#causes
- U.S. National Library of Medicine. (n.d.). Immune system and disorders | autoimmune disease. MedlinePlus. Retrieved November 16, 2022, from https://medlineplus.gov/immunesystemanddisorders.html
- Vitamin C. The Nutrition Source. (2021, May 27). Retrieved November 16, 2022, from https://www.hsph.harvard.edu/nutritionsource/vitamin-c/
- Vitamin E. Hsph.harvard.edu. (n.d.). Retrieved November 16, 2022, from https://www.hsph.harvard.edu/nutritionsource/vitamin-e/
- Wacker, M., & Holick, M. F. (2013, January 1). Sunlight and vitamin D: A global perspective for health. Dermato-endocrinology. Retrieved November 16, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3897598/
- Zinc. The Nutrition Source. (2022, March 2). Retrieved November 16, 2022, from https://www.hsph.harvard.edu/nutritionsource/zinc/