4  Foods & Nutrients That May Improve Your Immune Health
Article

4 Foods & Nutrients That May Improve Your Immune Health

Published on Friday, January 20, 2023
by
Andy De Santis

Health & Wellness

I hate to be that health writer who uses double negatives, but let’s be honest here…

Nutrition for immune health is never not a topic of great interest.

The fact we are headed into the coldest, darkest months of the year in North America only serves to heighten that intrigue.

With that said, let’s take a closer look at four foods and nutrients that play an above-average role in human immunity. 

Vitamin D 

Although it used to be thought of exclusively in terms of bone health, current science suggests that this elusive Vitamin has much more to offer to human health – including immunity.

One of the most practical examples of Vitamin D’s role in immunity was highlighted in a 2021 paper out of the European Journal Of Clinical Nutrition which identified that among individuals who got COVID, those with better Vitamin D status ended up with less severe forms of sickness.

I describe Vitamin D as “elusive” because very, very few foods, primarily fish, contain it in any meaningful quantity and it can otherwise be synthesized in our bodies via sun exposure.

The only problem is the sun in many parts of North America is not strong enough for significant portions of the year to elicit this effect, which is exactly why it is estimated that about 40% of Canadians have suboptimal blood Vitamin D levels during the winter months.

Of course, the risk is lower in those who eat multiple weekly servings of fish (especially salmon, mackerel, herring, trout, and sardines) as well as in those who supplement with Vitamin D3, which is perpetually among the top 3 selling supplements on Amazon.ca.

Fermented Foods & Prebiotic Fiber 

Given that the human digestive tract is home to 70%+ of our immune system, and that the health of the digestive tract is strongly based on the state of our gut bacteria, it simply follows that taking care of those bacteria will have a positive influence on our immune health.

And while a large array of healthy foods can potentially have a positive influence on the gut microbiome, I want to take a moment to focus on two subgroups in particular.

Fermented Foods 

Fermented foods contain various healthy bacterial species which can enhance the diversity in the gut microbiome and reduce the state of inflammation in our body.

Foods in this family include kimchi, kombucha, kefir, sauerkraut, and probiotic yogurts.

While no one needs to eat fermented foods to have a strong gut microbiome, they certainly may offer unique benefits above and beyond other standard healthy dietary choices.

Foods With Prebiotic Fiber

Prebiotic fiber is a fancy word for fiber that your gut bacteria preferentially enjoy using as “food” and thus supports their prosperity and growth.

In doing so, they create beneficial compounds known as SCFAs which improve immune health by strengthening the lining of the digestive tract, making it more resilient against invasive pathogens.

Examples of prebiotic-rich foods include apples, onions, garlic, leeks, barley, oatmeal, chickpeas, lentils, and asparagus.

Omega-3 Fatty Acids 

Inflammation is an important aspect of the human immune response but excess bodily inflammation over time can increase our risk of illness and infection.

Omega-3 fatty acids, as you’ve likely heard, are renowned for their anti-inflammatory capabilities and are considered an important dietary aspect to include to optimize immune health for this reason.

There are two primary types of omega-3 fatty acids, the types found in plant-based foods (short-chain omega-3) and the types found in seafood-based foods & most supplements (long-chain omega-3). 

Ideally, if it allows for it, your diet contains both – not least of which is the fact that many of the seafood choices high in omega-3 are also high in Vitamin D too.

These fish options, as mentioned previously, include salmon, herring, mackerel, trout, and sardines.

Plant-based foods highest in Omega-3 include flax seeds, chia seeds, walnuts, hemp seeds, and tofu.

There are also algae-based supplements on the market currently that contain long-chain omega-3 fatty acids for those who want to access these compounds but do not eat fish.

Green Tea 

It may be easy to underestimate the impact of something like tea, but the reality is that tea is actually the third top contributor of polyphenol antioxidants in the average American’s diet.

Tea is generally an antioxidant-rich beverage that contains many uniquely beneficial compounds, and green tea in particular as the main dietary source of Epigallocatechin gallate (EGCG) is of great intrigue because this compound has the potential to greatly enhance the functioning of certain immune cells.

Although more research in this area is needed before stronger claims can be made, I feel very comfortable with the idea that green tea has a role to play in enhancing human immune health as part of an overall strong diet and healthy lifestyle.


  1. Calder P. C. (2021). Nutrition and immunity: lessons for COVID-19. Nutrition & diabetes, 11(1), 19. https://doi.org/10.1038/s41387-021-00165-0
  2. Health at a glance. Vitamin D blood levels of Canadians. (2015, November 27). Retrieved December 29, 2022, from https://www150.statcan.gc.ca/n1/pub/82-624-x/2013001/article/11727-eng.htm
  3. Lehmann, U., Gjessing, H. R., Hirche, F., Mueller-Belecke, A., Gudbrandsen, O. A., Ueland, P. M., Mellgren, G., Lauritzen, L., Lindqvist, H., Hansen, A. L., Erkkilä, A. T., Pot, G. K., Stangl, G. I., & Dierkes, J. (2015). Efficacy of fish intake on vitamin D status: a meta-analysis of randomized controlled trials. The American journal of clinical nutrition, 102(4), 837–847. https://doi.org/10.3945/ajcn.114.105395 
  4. Wastyk, H. C., Fragiadakis, G. K., Perelman, D., Dahan, D., Merrill, B. D., Yu, F. B., Topf, M., Gonzalez, C. G., Van Treuren, W., Han, S., Robinson, J. L., Elias, J. E., Sonnenburg, E. D., Gardner, C. D., & Sonnenburg, J. L. (2021). Gut-microbiota-targeted diets modulate human immune status. Cell, 184(16), 4137–4153.e14. https://doi.org/10.1016/j.cell.2021.06.019 
  5. Blaak, E. E., Canfora, E. E., Theis, S., Frost, G., Groen, A. K., Mithieux, G., Nauta, A., Scott, K., Stahl, B., van Harsselaar, J., van Tol, R., Vaughan, E. E., & Verbeke, K. (2020). Short chain fatty acids in human gut and metabolic health. Beneficial microbes, 11(5), 411–455. https://doi.org/10.3920/BM2020.0057 
  6. Huang, Q., Braffett, B. H., Simmens, S. J., Young, H. A., & Ogden, C. L. (2020). Dietary Polyphenol Intake in US Adults and 10-Year Trends: 2007-2016. Journal of the Academy of Nutrition and Dietetics, 120(11), 1821–1833. https://doi.org/10.1016/j.jand.2020.06.016 
  7. Pae, M., & Wu, D. (2013). Immunomodulating effects of epigallocatechin-3-gallate from green tea: mechanisms and applications. Food & function, 4(9), 1287–1303. https://doi.org/10.1039/c3fo60076a

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