The Most Important Nutrients for Your Immune System This Fall

I think we can all agree that this year is unique in that we may very well have our typical cold & flu season coupled with a global pandemic and a virus we still don’t know a lot about. This makes it all the more important to know what you can do to strengthen and support your immune system heading into the fall.

Today we are starting with the most important nutrients for your immune system. These are the building blocks of a strong immune system (that many of us happen to be low in) and ones that we now know also play a role in defending your immune system against the virus.

By the way, we also have other immune resources here:

5 Ways to Prevent Getting Sick This Cold & Flu Season

5 Ways to Boost Your Child’s Immune System

Get Sick Often, It Might Be Due to This

Please note that while we list supplements and some suggested doses in this article, this is not meant to replace medical advice. It’s always a good idea to check with your healthcare provider, but especially if you have any pre-existing medical conditions or are on any medication.

The Most Important Nutrients for Your Immune System This Fall

Vitamin D

If you do nothing else this winter, PLEASE take vitamin D. Even better, get your levels checked. Here’s why...

When it comes to your immune system, vitamin D plays an important role in regulating your immune response. Deficiency in vitamin D is associated with an increased risk of autoimmune conditions as well as susceptibility to infection. You may have also seen vitamin D a lot in the media lately. This is because preliminary research (1, 2, 3, 4)  has found an association between vitamin D deficiency and the risk of getting COVID-19 and having a more severe outcome if you have it.

Reaching optimal vitamin D status is difficult through food alone, and things like reduced sun exposure, living in more Northern latitudes and darker skin all decrease absorption. In fact, studies have found that there are widespread deficiency issues even in sunny countries like Brazil. This is why we recommend you get your vitamin D levels tested and adjust your dose depending on where your levels are currently at. Grassroots Health recommends people maintain optimal 25(OH)D blood levels between 100 – 150 nmol/L (Canada) or 40-60 ng/ml (USA). Getting tested in Canada is usually around $60 so if that’s not an option for you, a good maintenance dose is around 2000 IU/day (You generally don’t want to take very high doses over the long-term, especially if you aren’t monitoring them).

Top vitamin D sources:

  • Direct sunlight every day is your best option
  • Top foods sources include salmon, mackerel, tuna and eggs (these are not generally enough alone though)

Preferred vitamin D supplements:

  • CanPrev Vit D3/K2 (K2 helps with the absorption of vitamin D)
  • Thorne Vitamin D3/K2 (send us an email if you’d like us to order this product for you)

Vitamin C

Vitamin C is absolutely essential when it comes to your immune system. It’s an important antioxidant that helps to regulate inflammation in the body (chronic inflammation puts your immune system at risk). Low levels of vitamin C results in impaired immunity and greater susceptibility of infections. It has been shown to reduce the incidence of upper respiratory tract infections in children and reduce the likelihood of catching a cold and speeding up recovery. Researchers are also exploring its use as a treatment for COVID-19 (source).

While it's difficult to be truly deficient in vitamin C in North America, many lifestyle factors like smoking, stress, and not eating enough fruits and vegetables deplete vitamin C levels and increase your daily needs. Your body doesn't store vitamin C because it’s a water soluble nutrient, so you need to keep getting it from the food you eat and possibly supplement if you are at risk of getting sick.

Good dietary sources of vitamin C:

  • Bell peppers
  • Kiwis
  • Broccoli
  • Brussels sprouts
  • Oranges
  • Leafy greens (spinach, kale, swiss chard)
  • Papaya
  • Strawberries
  • Lemons

Preferred vitamin C supplements:

HEAL Supplement Dispensary


Zinc is one of the key nutrients needed for your immune system to function properly. Because of the important role of zinc in regulating the immune system, deficiency is thought to play a role in autoimmune conditions, allergies and inflammatory conditions like rheumatoid arthritis, diabetes, atherosclerosis, impaired cognitive function, as well as age-related macular degeneration.

In a 2015 review of 16 studies, the researchers found that zinc administered within 24 hours of onset of symptoms reduces the duration of common cold symptoms in healthy people (note that this level was well above the amount you should take for general health).

Your body doesn’t store zinc, so it’s important to eat zinc-rich foods on a regular basis in order to give your immune system the building blocks it needs.

Good dietary sources of zinc:

  • Seafood like shrimp, mussels and oysters
  • Pumpkin seeds
  • All kinds of meat, especially red meat (we suggest grass-fed)
  • Cashews
  • Legumes like chickpeas, lentils and beans
  • Whole grains *soak whole grains and legumes for better absorption of nutrients
  • Eggs

Preferred zinc supplements:


Your gut houses over 70% of the cells of your immune system and inflammation in your gut can very quickly lead to chronic inflammation, putting you at risk of illness and infection as well as autoimmune disease. There are also trillions of bacteria that live in your gut (called your microbiome) that help neutralize unwanted bacteria and viruses. Like we highlighted back in April, other areas of your body, like your lungs, have their own microbiome and they interact with the bacteria in your gut. This is important because it highlights just how important it is to support a healthy gut and microbiome.

There are many ways to support your gut health (more on that here), but eating probiotic foods is one of the important ones.

Good dietary sources of probiotics:

  • Fermented foods like miso, kimchi, kombucha (low sugar brands), sauerkraut, yogurt and kefir (go dairy-free if you don’t tolerate dairy), tempeh, apple cider vinegar and naturally pickled vegetables.

Preferred probiotic supplements:

To grab the above supplements, click here. Then, click Catalog, and HEAL’s Supplement Dispensary Favourites.

In Summary

Does supplementing with the above nutrients mean you will never get sick? I wish it were that simple! But addressing nutrient deficiencies, inflammation, and getting your immune system nutrients to optimal levels now, is one of the things you can do today to protect yourself from either getting sick as often or developing a more severe outcome from an illness or infection this fall/winter.

If you’d like 1:1 coaching to optimize your immune system this fall, please contact us here.

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