The Seasons Are Changing: Here’s How You Can Support Immune Health

By Molly Knudsen, MS, RDN

Some things never change: The kids go back to school in the fall, the leaves change color shortly after, the holiday season approaches with increasing speed every passing year, and the cold or flu always seems to hit a household when all of these festivities are happening.

We know from experience that the common cold and flu hit the hardest when the weather gets the chilliest, but why is that? And can probiotics really help support your immune health so you can enjoy the holidays approaching?

Are the seasons actually connected to health?  

According to science, it turns out that there are three main ways that the seasons may influence health.

1. Environmental factors: One of the main predictors of disease rates across the globe is temperature.¹ For example, evidence shows that both the northern and southern hemispheres have higher rates of seasonal respiratory viruses during their respective winter months.¹ In addition, lower humidity levels (so dryer climates) are also associated with higher rates of these viruses.¹ Humidity is believed to influence a virus’ stability and its ability to pass the infection on.¹ Although these trends of virus prevalence are well-observed, more research is needed in this area as to why.

2. Gene expression: Studies have found that 94 DNA transcripts, the basis for gene expression, show seasonal variability.² This variability was found in transcripts involved with immune function.² If the gene expression for immune function isn’t functioning optimally, that person may be more susceptible to these seasonal conditions.

3. Human behavior: Cold weather usually changes people’s routines. As temperatures drop, people are likely to spend more time indoors and in confined areas, so viruses can spread easily by contact. Because people are inside more often and the sun is shining less, vitamin D levels tend to drop in the winter.¹ Vitamin D is also believed to play a role in the immune response.¹

How can you use nutrition as a tool to support your immune system this season?

Common colds are so common that, on average, adults usally experience two to three per year, and kids often contract more, making colds the main culprit for missed days of work and school.³ Maintaining proper immune system function is especially important during this time. There are many simple habits you can start today to help keep the cold and flu at bay.

Key vitamins and probiotics may also play a role in maintaining immune health. The age-old remedy of drinking orange juice for immune health may actually hold some validity. Oranges are high in vitamin C, and this vitamin has been shown to be a powerful antioxidant that contributes to the body’s immunity.⁴ Not getting enough vitamin C can impair immunity and weaken your body’s immune defense.⁴ Foods that are high in vitamin C include guavas, red bell peppers, tomatoes, and the ever-popular orange juice.

Vitamin D also plays an important role in immune function. Vitamin D receptors are expressed on various immune cells and can modulate immune response.⁵ It is common for vitamin D levels to drop in the winter months, and oftentimes people may not even be aware if they are deficient in this nutrient.¹ Low vitamin D levels are also associated with impaired immune function.⁵ Foods that contain vitamin D include fortified dairy products and plant-based dairy alternatives, fatty fish like salmon, and eggs. Some orange juices are also fortified with vitamin D.

A staggering 70% of the immune system is located in the gut, and one not-so-intuitive habit to maintain your immune health, in addition to getting adequate amounts of these key vitamins, is to consider probiotics.⁶ Research shows that the probiotic strains Lactobacillus acidophilus NCFM and Bifidobacterium lactis Bi-07 may help support immune function.⁷

These are the potential modes of action for how certain probiotics may support the immune response:⁸

• Preventing harmful bacteria or viruses from attaching to the intestine
• Making compounds that prevent other microorganisms from growing in the intestine
• Producing beneficial substances that promote intestinal health
• Modulating the immune system (the interaction of probiotics in the gut and immune cells throughout the body)

Adding probiotics to your daily routine is like adding one more tool to your toolbox for supporting your immune health this winter. Speak to your healthcare practitioner before changing your diet or incorporating the strategies mentioned above. 

For more information on probiotics and immune health, please visit the Metagenics blog.

References

1. Sloan C et al. Impact of pollution, climate, and sociodemographic factors on spatiotemporal dynamics of seasonal respiratory viruses. Clin Trsl Sci. 2011;4(1):48-54. 
2. Goldinger A et al. Seasonal effects on gene expression. PLoS One. 2015;10(5):e0126995. 
3. Common colds: protect yourself and others. CDC. https://www.cdc.gov/features/rhinoviruses/index.html. Accessed September 24, 2019.
4. Carr AC et al. Vitamin C and Immune Function. Nutrients. 2017;9(11):1211.
5. Aranow C. Vitamin D and the immune system. J Investig Med. 2011;59(6):881–886.
6. Vighi G et al. Allergy and the gastrointestinal system. Clin Exp Immunol. 2008;153(Suppl 1):3–6.
7. Kang E-J et al. The effect of probiotics on prevention of common cold: a meta-analysis of randomized controlled trial studies. Korean J Fam Med. 2013;34(1):2-10.
8. Bermudez-Brito M et al. Probiotic mechanisms of action. Ann Nutr Metab. 2012;61(2):160-174.