Lately, our clinic has been flooded with cases of viral infections—from persistent upper respiratory issues to digestive disturbances and sinus infections. It is the time of the year when our immune system needs to stay robust and adaptive as we encounter the seasonal changes and new viral challenges.

The immune system is not just a defense mechanism; it’s a complex network that requires proper nourishment and care to function optimally. Let’s explore the role of specific immune-boosting nutrients, why gut health is foundational for a resilient immune response, and how sleep, stress, and dietary sugar impact our body’s ability to fend off illness.

Whether you’re recovering from a recent infection or looking to prevent future ones, these insights will empower you to make choices that strengthen your immune defenses.

Supplements to Consider for ❄️Seasonal Immune Support

But first to be clear: 

“Seasonal support” supplements are meant to strengthen immune function over weeks or months—not to be confused with “temporary support” products, which are best taken when you’re already feeling unwell.

Here they are!

1. Reishi

Reishi (Ganoderma lucidum) is a medicinal mushroom, traditionally used as an adaptogen to support stress resilience. It is rich in beta-glucans, which modulate immune function over time. Powdered reishi can be mixed into coffee or brewed as tea.  

Reishi:

• Balances the immune response by enhancing the activity of natural killer (NK) cells, which target pathogens and abnormal cells.

• Contains beta-glucans, compounds that stimulate macrophages and dendritic cells to improve immune vigilance.

• Reduces chronic inflammation, supporting a healthy immune environment.
  

  2. Probiotics

Since 70%-80% of the body’s immune cells reside in the gut, a healthy gut microbiome is essential for supporting immune defenses. Probiotics can be consumed as supplements or in fermented foods. 

Probiotics, especially strains like Lactobacillus and Bifidobacterium, are essential for immune health:

• They modulate immune function by promoting regulatory T cells (Tregs), which prevent autoimmune responses.

• Strengthen the gut lining, reducing the risk of pathogens entering the bloodstream.

• Aid in the production of short-chain fatty acids (SCFAs), which have anti-inflammatory properties.

3. Vitamin D

Especially during darker months, consuming enough vitamin D is essential for immune function. Studies show that low vitamin D levels increase the risk and severity of infections. Vitamin D can be taken as pills. If you don’t know your vitamin D level, ask to get it checked!

Vitamin D is pivotal for both innate and adaptive immunity, it:

• Enhances the production of antimicrobial peptides, like cathelicidin, which directly destroy pathogens.

• Helps regulate immune cell differentiation, reducing the risk of autoimmune conditions.

• Deficiency is linked to higher susceptibility to respiratory infections and poor immune resilience.

4. Elderberry

Studies show that elderberry (Sambucus nigra) probably does not prevent the common cold or flu, but it may shorten the duration or reduce the severity.

Elderberry is:

• Rich in flavonoids like quercetin, elderberry inhibits viral replication and strengthens the mucosal immune response.

• Shown to reduce the duration and severity of cold and flu symptoms.

5. Vitamin C

There has been a lot of controversy around vitamin C, but a 2023 meta-analysis found that compared to placebo, vitamin C reduced the severity of the common cold by 15%. It may not shorten the duration of mild colds, but it may shorten severe colds. These stats are based on people who took at least 1 gram of vitamin C per day and who were healthy at baseline.

This water-soluble antioxidant is a cornerstone of immune health:

• Neutralizes free radicals, protecting immune cells from oxidative damage.

• Enhances white blood cell activity, especially phagocytes and lymphocytes.

• Supports the skin barrier, the body’s first line of defense.

6. Zinc

A 2024 comprehensive review of 34 studies on zinc in relation to the common cold found all kinds of mixed results but in the end, it concluded that zinc supplements may not prevent colds but may reduce the duration of ongoing colds.

Zinc is critical for the proper functioning of the immune system, as it:

• Supports thymus gland activity, which produces T cells, key players in adaptive immunity.

• Helps maintain skin and mucosal barriers.

• Zinc deficiency impairs cytokine production, increasing susceptibility to infections.

Our immune systems are beautifully complex, so we can never expect a single nutrient or herb to be an overnight success. Still, I like to keep these supplements on hand for a boost of support when I start to feel off. 

Gut Health: The Foundation of Immunity

If you’re interested in a root-cause approach to health, we’re inevitably going to have to talk about the gut microbiome!  Over 70% of the immune system resides in the gut-associated lymphoid tissue (GALT) and affects:

• Microbiome diversity enhances immune adaptability, helping the body respond appropriately to pathogens while preventing overreactions like allergies.

• A healthy gut barrier prevents the entry of harmful microbes and toxins, reducing systemic inflammation.

• Probiotic strains and dietary fiber feed beneficial bacteria, promoting the production of SCFAs, which modulate inflammation and immune signaling.

But wait, there is also new research on the gut microbiome 🦠

Now researchers at Rutgers University have given us a new way to talk about the gut micorbiome. They call it the “Core Microbiome”—the crucial group of microbes that play a role in digestion, immune function, and even mental health. 

The researchers determined that the Core Microbiome consists of:

1️⃣ The Foundation Guild

Helpful bacteria that break down dietary fibers to produce short-chain fatty acids (SCFAs) and keep harmful bacteria in check. 

2️⃣ The Pathobiont Guild

Needed in small amounts to “educate” the immune system, these microbes can drive disease if they become dominant.

When you take a larger perspective of immune health, don’t forget about your gut.

The Impact of Sleep on Immune Tone

Quality sleep is one of the best lifestyle habits you can do for your immune system. Quality sleep is vital for immune health:

• During sleep, the immune system releases cytokines that help fight infections and reduce inflammation.

• Chronic sleep deprivation lowers NK cell activity and impairs T cell responses.

• Deep sleep promotes the memory of immune cells, aiding the body’s ability to recognize and respond to pathogens.

Stress and Immune System Response

For many people, stress and holidays go hand in hand. We’ll delve more into stress tricks to help you get back to enjoying the holidays in upcoming blogs.

Stress profoundly impacts immunity through the hypothalamic-pituitary-adrenal (HPA) axis:

• Cortisol, the stress hormone, suppresses the production of white blood cells and reduces inflammatory cytokine activity.

• Chronic stress shrinks the thymus gland, impairing T cell production.

• Stress also disrupts gut health, reducing the diversity of the microbiome and weakening the gut barrier.

How Processed Sugar Weakens the Immune System

We are what we eat. High sugar intake has an immediate and lasting impact on immune function:

• Consuming 75-100g of sugar suppresses white blood cell activity for up to five hours, reducing their ability to engulf pathogens.

• Promotes dysbiosis (microbial imbalance) in the gut, leading to inflammation and a weakened immune response.

• Chronic high sugar consumption exacerbates insulin resistance, which is linked to a pro-inflammatory state.

Building a Resilient Immune System

You can build a resilient immune system capable of adapting to life's challenges while fostering overall vitality. Small, consistent changes in diet, lifestyle, and stress management go a long way in achieving this goal. Take 1 or 2 tips and incorporate them today:

1. Prioritize Immune-Boosting Nutrients: Incorporate foods rich in probiotics, vitamin C, zinc, and elderberry into your diet. Consider supplements like vitamin D and reishi mushroom if needed.

2. Support Gut Health: Focus on a fiber-rich diet, fermented foods, and limit processed foods that harm microbiota diversity.

3. Optimize Sleep: Aim for 7-9 hours of quality sleep, maintaining a consistent sleep-wake cycle to align with your circadian rhythm.

4. Manage Stress: Practice mindfulness, yoga, or breathing exercises to reduce chronic stress and its immune-suppressing effects.

5. Reduce Sugar Intake: Minimize processed sugar to keep your immune system in peak condition and support a healthy microbiome.

Your health starts with the choices you make today—nourish your immune system and let it work its best!

If you find you are struggling to get through the colds of the season, schedule an appointment for holistic & integrative care.