12 Tips to Support your Immune System During Cold and Flu Season

Ali Segersten Nov 28, 2023 1 comment

Cold and flu season is upon us! How can you support your immune system to function its best? Your immune cells, like all other cells, require good nutrition and lifestyle habits to function properly. A nourishing whole foods diet, strong digestive system, good sleep practices, good hydration, blood sugar control, and the addition of supportive nutritional supplements (when needed) all work together to promote a strong and functional immune system.

Your requirement for nutrients goes up during cold and flu season! This is because we are continually getting exposed to bacteria and viruses that our immune systems need to respond to. You may not even realize you are fighting off an infection if your immune system is functioning well and removing the unwanted pathogen. However, large amounts of nutrients are needed to run your immune cells so they can do their jobs. During cold and flu season, there is an increased need for these nutrients.

Below you’ll find a brief overview of the key components for supporting your immune system during cold and flu season. 

12 Tips for Supporting your Immune System:


1. Control Blood Sugar:

Reduce or eliminate sugar in your diet! A diet high in refined sugar and carbohydrates can keep blood sugar levels elevated. Consistently elevated blood sugar suppresses the immune system so it can’t properly fight off invading bacteria and viruses. Sugar does this by slowing down white blood cells. For example, if your white blood cells can’t immediately respond to a virus that’s invading your cells, that virus will quickly replicate and become a full-blown illness and may knock you out for many days to weeks. Start your day with a low-carb, high-protein, high-fat breakfast and see how you feel for the rest of the day. This is a great way to prevent a blood sugar roller coaster that can result from a high-glycemic breakfast. If you are a Nourishing Meals member, use the Search page and plug in Low-Carbohydrate + Breakfasts to find high-protein breakfast recipes

2. Sleep:

Sleep deprivation suppresses immune function. In fact, it is difficult to produce enough natural killer cells and antibodies when you are sleep deprived! Additionally, sleep deprivation increases cortisol; chronically elevated cortisol will also suppress immune function. Sleep is critical to keeping your immune system functioning at its best. Slow down, rest, and practice good sleep hygiene at night like keeping all blue-spectrum lights in your home off or wearing blue-light blocking glasses. Don’t eat large meals in the evening, or, instead, eat dinner early. Go to sleep by 9 or 10pm and get early morning sunlight to help your body attune to a natural circadian rhythm. 

3. Protein:

Immune cells are one of the types of cells in the human body that turnover rapidly. Large amounts of amino acids are needed to make immune cells! Amino acids are found in protein. To break down protein into amino acids your digestive system needs to be functioning properly! This means that you need to have adequate stomach acid and enzyme production to get amino acids from your food. Drugs that reduce stomach acid can create amino acid deficiencies. Low stomach acid from stress or trauma, or due to low thyroid hormone or hypothyroidism, can be other contributors of amino acid deficiencies. It may be important to supplement with something called betaine HCL in order to properly break down proteins and absorb micronutrients such as B12, calcium, and iron. You may want to consider working with a health care practitioner to assess digestive functioning. If you take betaine HCL and feel an increased burning sensation in your stomach, then you probably don’t need this supplement. A basic digestive enzyme may be all that is needed. High-quality eggs, seafood, and meats; legumes; and nuts and seeds are good sources of amino acids. An amino acid supplement may also be helpful, depending on the state of your health and digestive capacity.

4. Vitamin D:

Vitamin D is more like a hormone rather than a vitamin. We make vitamin D after exposure to sunlight; however, we can only do this from about April through October in the northern hemisphere if you live above the 35th parallel. We have receptors on our cells, called VDR receptors. Once vitamin D gets inside a cell it regulates the expression of over 900 genes! Vitamin D deficiency is associated with an increased susceptibility to infection as well as autoimmunity. Vitamin D is a powerful modulator in both immune responses—the first line of defense called the innate immune system, and the adaptive immune system that creates memory (antibodies) to pathogens. Vitamin D can rev up and dampen down immune functions so everything runs smoothly. You don’t want to under-respond (immune suppression) or over-respond to pathogens (excessive inflammation). Vitamin D keeps your immune system balanced so it functions how it needs to. Without adequate vitamin D, you may find yourself getting sick frequently, or unable to get over an infection quickly. Vitamin D works in conjunction with all other nutrients to support the immune system. Supplementation of vitamin D in the fall and winter is usually required to keep vitamin D levels at optimal levels in the body.

5. Vitamin A:

Vitamin A is stored in your epithelial tissues, reproductive system, and eyes. Vitamin A supports immune function in your mucous membranes and is needed to fend off respiratory transmitted viruses and bacteria. Without adequate vitamin A in our epithelial tissues, we have an increased susceptibility to infections. Vitamin A supplementation can be toxic in large doses; therefore, it is important to consider nutrient testing before regularly supplementing with this fat-soluble vitamin. However, short-term supplementation at lower doses may be beneficial during cold and flu season. Vitamin A is found in both animal and fish liver, as well as egg yolks, pastured butter, and milk. Vitamin A can also be made in the body by converting carotenes to preformed vitamin A. This process involves zinc, so be sure to be consuming enough zinc if you do not consume sources of preformed vitamin A, which can only be found in animal foods. Foods high in carotenes include dark leafy greens like collards, kale, mustard greens, parsley, dandelion greens, and spinach. Other excellent sources of carotenes include winter squash, dried apricots, sweet potatoes, carrots, mangoes, and other orange and yellow vegetables.

6. Vitamin C:

Your non-specific immune cells—the first line of defense that occurs within minutes and hours of pathogen detection—requires vitamin C for many of its functions. Vitamin C is also needed to mop up the inflammatory chemicals created during these processes. Without enough antioxidant support to help clean up the mess, you’ll feel the effects of increased inflammation—pain, chronic fatigue, moodiness, and brain fog. Vitamin C needs to be consumed continuously to see a benefit. Raw fruits and vegetables are full of vitamin C! Strawberries, papaya, citrus fruits, pineapple, and kiwis are particularly high in vitamin C, however, bell peppers, brussels sprouts, and broccoli are higher in vitamin C that most fruits! You just need to eat them in their raw form to get the benefit as vitamin C is easily destroyed by heat. Another important function of vitamin C is to replenish the oxidized form of vitamin E. Meaning, when vitamin E is used as an antioxidant and becomes a “vitamin E radical,” vitamin C can come in and restore vitamin E to its normal antioxidant state. Try my Citrus-Ginger Immunity Shots to increase vitamin C and citrus bioflavonoids. 

7. Vitamin E:

Cell membranes are made of phospholipids and are very susceptible to damage from free radicals. Vitamin E works as an antioxidant to protect cell membranes from damage. Cells of the immune system, specifically phagocytic cells, need to have adequate levels of vitamin E stored within them to protect against oxidation. These types of immune cells produce large amounts of reactive oxygen species (free radicals) to “poke holes” into invading pathogens. Therefore, to protect themselves from their own free radicals, they need vitamin E stored within the cell membranes to keep themselves alive and functioning. Vitamin E is a very common nutrient deficiency! It may be a good idea to use a supplement (talk to your health care provider about purchasing a high-quality natural vitamin E supplement as they are not all created equal). The best food source of vitamin E is sunflower seeds! Other excellent sources include almonds, unrefined sesame oil, peanuts, extra virgin olive oil, and peanut butter. Try this delicious herbed sunflower seed salad dressing made from soaked, raw sunflower seeds!

8. Methyl Donors:

Rapidly turning-over cells, such as immune cells, need methylation and methyl donors for cell differentiation and function. Folates found in dark leafy greens and legumes, B12 found in animal-based foods, and betaine found in beets, shrimp, and crab all work together to make the methylation cycle run smoothly. If you have genetic mutations that greatly reduce forming the active, methylated forms of folate and B12, then you may consider supplemental support using the methylated forms of both B12 and folate. Methylation also requires B2, B6, magnesium, and zinc! This is why consuming nutrient-dense foods daily and taking supplements when needed is so important.

9. Zinc:

Viruses need the cells in your body to replicate. Once a virus enters your cell, it hijacks its machinery and uses the cell as a virus-replicating machine. What stops this process inside the cell? Zinc! However, zinc often doesn’t easily enter cells. Certain phytonutrients in plant foods help zinc enter the cell! Quercetin (found in apple skins and onions) and green tea extract (EGCG) are two plant chemicals that do this beautifully. Zinc is also needed for protein and DNA synthesis. It only takes a few weeks of eating a low-zinc diet to reduce immune function! Which foods are high in zinc? Oysters, pasture-raised beef, and lamb are the highest food sources of zinc. Pumpkin seeds and lentils are also very good sources. Turkey and chickpeas are also good sources. Inflammatory bowel disease and very poor gut health can impair zinc absorption, so it is very important to work on improving gut health to be able to absorb zinc. Additionally, zinc from plant foods is typically not as absorbable as zinc from animal foods. 

10. Selenium:

Selenium is an important mineral that is needed for antioxidant functions in the body. Selenium and glutathione work together to create a group of enzymes called glutathione peroxidases, which are critical for reducing cellular oxidative stress (reducing free radicals inside our cells). Selenium-containing enzymes also recycle vitamin C from its oxidized form (used form) back into its reduced form (active antioxidant form). Proper thyroid function is dependent on selenium as it is needed to transform T4 (less active thyroid hormone) into T3 (the more active form of thyroid hormone). Remember, thyroid hormone is needed to stimulate stomach acid production, and adequate stomach acid is the first step in breaking down your food so you can utilize all of the micro and macro nutrients you consume! Selenium can be found in brazil nuts, as well as seafood and meats. 

11. Medicinal Mushrooms:

Shiitake, reishi, maitake, turkey tail, and cordyceps mushrooms can help to stimulate a TH1 immune response and increase TH1 cytokines. Early on in an infection, a strong TH1 response is desirable. TH1 cytokines activate other T cells, natural killer cells, macrophages, and neutrophils to destroy pathogens. TH1 cytokines also increase something called antigen presentation, so the immune system sees and knows what to destroy. Just think of it this way: Eating mushrooms makes your white blood cells communicate with each other properly and do what they are supposed to do. Medicinal mushrooms can also act as adaptogens—or substances that can regulate the immune response and can reduce TH1 cytokines when necessary. Try my Super Immune-Boosting Chicken Soup to get in a healthy dose of shiitake mushrooms!

12: Rosmarinic Acid:

This potent phytochemical is found in spearmint, peppermint, sage, thyme, lemon balm, basil, holy basil, oregano, and rosemary. It is an antiviral, antioxidant, and anti-inflammatory. Rosmarinic acid can inhibit viral replication. Fresh herbs are not just for flavor! They are potent natural medicines that can help reduce viral load, reduce viral entry into cells, and help reduce inflammation from an infection when needed. Stir chopped fresh herbs into soups and stews, add mint to smoothies, add fresh herbs to salads and salad dressings


There are many other foods and herbs that can be supportive to a healthy immune response. Astragalus, for example, helps stimulate a healthy TH1 immune response, though this may not always be ideal if you are in an uncontrolled stage of an autoimmune disorder. Elderberry, raw garlic, raw manuka honey, ashwagandha, ginger, curcumin (turmeric), and certain strains of probiotics are other foods and supplements that be very supportive to the immune system. 

Remember, your best medicine is to have a regular practice of consuming daily nourishing meals, drinking plenty of water (your immune cells can't function properly if they are dehydrated), supporting your digestive system, sleeping deeply, moderate exercise, and practices to relax and destress such as time in nature and meditation. Removing foods that your body may be sensitive to can help to calm down an overactive immune system and reduce excess inflammation. An Anti-Inflammatory Diet or Elimination Diet can help with this. Our membership portal offers over 1600 nourishing recipes and a meal planning system to help you stay on track with consuming nourishing, whole foods daily.  Join now to start your nourishing meals journey to health, wellbeing, and longevity.


About the Author

Ali Segersten

Alissa Segersten holds a Bachelor's of Science in Nutrition from Bastyr University and a Master’s of Science in Human Nutrition and Functional Medicine from the University of Western States. She is a Functional Nutritionist, the mother of five children, a whole foods cooking instructor, professional recipe developer, and cookbook author. She is passionate about helping others find a diet that will truly nourish them. Alissa is the author of two very popular gluten-free, whole foods cookbooks and guidebooks: The Whole Life Nutrition Cookbook and Nourishing Meals. She is also the co-author of The Elimination Diet book. Alissa is the founder and owner of Nourishing Meals®.

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Thank you for this article - very informative 👍. Appreciated.

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