Boosting Your Immune System with Food
Now more than ever, it’s time to start thinking about being proactive (versus reactive) in taking our health, immunity, and self-care habits to the next level. During the coronavirus COVID-19 pandemic and now moving into cold/flu season, preventive protocols such as handwashing, sanitizing, masks and social distancing will continue to go a long way to help reduce the spread of viruses and infections…
But nutrition and a healthy lifestyle also play a vital role in supporting a healthy immune system too! This is information that (from my perspective, speaking as a dietitian and healthcare provider) shouldn’t be overlooked or dismissed!
This isn’t medical advice. This is general information about food and immunity. These are complementary recommendations, not to replace wearing masks, practicing social distancing, handwashing, and sanitizing. There’s no guarantee that a supplement or food will prevent or cure an infectious disease.
With the 2019-2020 COVID-19 pandemic, it’s especially important to understand that no supplement, diet, or other lifestyle modification can replace masks, social distancing, and proper hygiene practices to protect you from COVID-19.
Nutrition for boosting your immunity
Hundreds of thousands of clinical studies have revealed the strong connection between nutrition and the immune system! It isn’t new or controversial to acknowledge that a variety of whole, nutrient-dense fruits, vegetables and herbs help to bolster, nourish, and support healthy immunity.
For example, certain micronutrients (vitamins and minerals) are proven to help the immune system by nourishing and supporting our protective barriers (gut/skin), play direct roles as “cofactors” (assistants) in different cell jobs within our immune system, and also to help our bodies make antibodies, which are immune cells which help fight off viruses and other pathogens (1)…
The behind-the-scenes “dance” and synergy among vitamins, minerals and immunity may be a bit fancy and complicated, but when it comes to getting the right nutrients for our immune system, it can still be simple and easy. We don’t need to look any farther than our local grocery store or farmer’s market!
Vitamin C is an antioxidant and cofactor (“assistant”) in many chemical reactions in the body.
Although we only need about 10 milligrams of vitamin C per day (which can be met with about two swigs of 100% orange juice) to prevent scurvy, we’re best off with getting at least 100 to 200 milligrams of daily vitamin C from our diet and/or supplements to optimize our immune system function (2).
We only need about two to three servings of vitamin C-rich fruits per day to make that happen, generally speaking. (Not bad!)
It’s important to note that vitamin C is a “water-soluble” vitamin, so it can’t be easily stored in the body. In other words: we flush water-soluble vitamins out as we hydrate, and thus we must replenish our vitamin C from food and/or supplements daily.
Although most of us think of vitamin D for bone health, this “sunshine vitamin” is also a main player in our immune system. Not only has vitamin D been shown to help modulate (bring into balance) our immune system; studies have found vitamin D deficiencies are linked with increased risk of infection and autoimmunity (3).
It’s difficult to get the daily amount of vitamin D3 needed from food alone. Everyone has their own unique individual needs, but generally speaking most of us can benefit from at least 1000 to 2000 IU per day of vitamin D3.
- Pro-tip: Make sure to take vitamin D with a meal, since it’s fat-soluble and we’re less likely to absorb this one on an empty stomach!
Beta Carotene (Vitamin A)
Beta-carotene, the orange pigment and antioxidant responsible for the orange color of veggies like carrots and sweet potatoes (to name a few), is also the pre-cursor of vitamin A.
Both beta-carotene and vitamin A are well researched and known for more than just healthy eyesight… beta-carotene and vitamin A also both play major roles in strengthening and modulating different aspects of our immune response (4)! These nutrients are involved in the structure and function of lots of different cells that make up our immune system (4).
There’s some risk and controversy around supplementation. In the next section below, you can find more details on how to optimize your beta-carotene and vitamin A intake naturally through orange veggies.
In addition to playing an important role in men’s health, this mineral is also well-known to have multiple direct and indirect roles in immunity (5). From immune cell function to serving as a messenger (via “signal transduction”) and gatekeeper (5), getting enough zinc from our diet and/or supplements is not optional when it comes to a healthy immune system!
On average, healthy adults need about 30 milligrams of zinc daily, from food and/or supplements.
A lack of taste is associated with a functional and/or clinical zinc deficiency. Consider asking your doctor for a serum zinc blood test if your ability to taste is not up to par!
- Caution: Too much zinc will interfere with copper balance in the body, so consult a registered dietitian or doctor before taking zinc supplements daily or long-term.
Fruits and vegetables for immunity
Oranges, grapefruit, clementines, lemons and limes are top of mind when it comes to the citrus family of fruits. Any and all of these will provide a wonderful boost of vitamin C! Just one orange will provide about 50 milligrams of vitamin C, meeting ~25 to 50% of our daily need.
- Caution: Avoid grapefruit if you’re on a cholesterol-lowering medication such as a statin drug. Grapefruit also interacts with certain types of other medications, so double-triple-check for food-drug interaction warnings if you’re on any kind of medication.
To build on what I mentioned above, orange veggies like carrots, sweet potatoes, butternut squash and turnips are a gold mine when it comes to beta-carotene and vitamin A. Since these nutrients, like vitamin D, are “fat-soluble”, we only need about four servings of orange veggies each week to get what we need from food.
- Pro-tip: Enjoy your orange veggies with a small amount of butter, dressing, or olive oil to enhance the vitamin absorption rate!
From spinach to kale, mustard greens to microgreens, arugula to Swiss chard and watercress – raw, cooked or juiced – greens are something that have been a major part of my daily life for many years. Greens are a powerhouse of immunity-boosting nutrients, including but not limited to: vitamin A, beta-carotene, and vitamin C, as well as antioxidants like chlorophyll and bone-health supporting vitamin K too.
You don’t need to love salads to reap the benefits of this group of super-foods. Try adding leafy greens to juices, smoothies, pasta dishes, omelets or stir-fry on a regular basis – your mind and body will thank you for it!
- Caution: People on blood thinning medication (like Coumadin or Warfarin) need to keep their vitamin K intake consistent day to day, as this impacts the medication dosing recommendations. If leafy greens are a part of your routine, make to keep the daily amount of green veggies intake consistent – and keep your doctor in the loop too!
- For more meal planning ideas and resources related to leafy greens, check out this free meal planning guide. Again, your mind and body will thank you. 😊
Strawberries, blueberries, blackberries and raspberries are all wonderful ways to boost your vitamin C and antioxidant intake (in addition to citrus!). Berries are my personal favorite to have with oatmeal, cereal, waffles or just as a snack with a side of dark chocolate.
- Fun fact: Blueberries were actually a gateway into my world of nutrition, back in 2004 – in case you haven’t noticed, I never looked back since! 😉
All types of onions, raw or cooked, red or yellow or white, are proven wonderful for our health in many ways. Red onions have a special phyto-chemical called quercetin which has been proven to help support and regulate certain types of cells in our immune system when consumed consistently (6).
Herbs for immunity
Although I talk more about these in-depth in my “Nutrition and Herbs for Immunity” blog post (and even more so in my recent eBook, Herbal Potions for Immunity), I thought it would still be helpful to include these for your reference:
- Adaptogen herbs
Gut health and immunity
Gut health also plays a major role in our immune system. (Did you know that about 70% of our immune system is IN the gut?!) That said, here are 4 foods that support a healthy gut, and thus, help to strengthen your immune system:
Foods for gut health
I hope this information makes its way into your household for many years to come. I’d love to hear your feedback in the comments if you get the chance to try anything out. You’re also welcome to join our private Facebook community of holistic-minded individuals if you’re feeling ready to up-level your health and immunity even more.
Stay safe and well!
- Maggini S., Wintergerst E.S., Beveridge S., Hornig D.H. Selected vitamins and trace elements support immune function by strengthening epithelial barriers and cellular and humoral immune responses. J. Nutr. 2007;98:S29–S35.
- Carr, Anitra C, and Silvia Maggini. “Vitamin C and Immune Function.” Nutrients vol. 9,11 1211. 3 Nov. 2017, doi:10.3390/nu9111211
- Aranow C. Vitamin D and the immune system. J Investig Med. 2011;59(6):881-886. doi:10.2310/JIM.0b013e31821b8755
- Mora JR, Iwata M, von Andrian UH. Vitamin effects on the immune system: vitamins A and D take centre stage. Nat Rev Immunol. 2008;8(9):685-698. doi:10.1038/nri2378
- Haase H, Rink L. Multiple impacts of zinc on immune function. Metallomics. 2014 Jul;6(7):1175-80. doi: 10.1039/c3mt00353a. PMID: 24531756.
- Penissi A.B., Rudolph M.I., Piezzi R.S. Role of mast cells in gastrointestinal mucosal defense. 2003;27:163–172.