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Beat Flu Season With These Natural Immune Boosters & Natural Remedies

woman sick on the couch

Cold and flu season is here, and protecting ourselves with natural immune boosters is a great way to plan ahead.

No matter where you are on your health journey, the “common cold” can knock you down. We all know the symptoms; the chills, fever, sore throat, and congestion feel anything but common.

But before you reach for the hand sanitizer in terror, take a breath. There are plenty of natural immune boosters that won’t harm your microbiome (in fact, some of them will even strengthen it!) to work with your immune system. Consider incorporating a few of these tips into your routine for a kinder, gentler, Fully Functional® cold season.

brussels sprouts in a bowl

Vitamin C

Let’s start with the familiar. There’s definitely some validity to the classic advice that drinking a glass of orange juice will ward off the common cold. Research suggests that vitamin C is a key nutrient involved in our immune function, including the function of phagocytes and T-cells. Low levels of this nutrient may make us more susceptible to sickness.¹

However, chugging orange juice probably won’t reduce your risk of getting sick — perhaps just decrease the severity of your illness when you do fall ill. What’s more, the unregulated sugar hit you get from 8 oz of orange juice may further disrupt your system. Not exactly what we’d like to have happen.

Instead, I recommend regularly working vitamin C-rich vegetables into your diet as a means of preventatively shoring up your vitamin C stores. Vitamin C-rich foods include brussels sprouts, broccoli, kale, cauliflower, bell peppers, and parsley. Many of these foods actually contain more vitamin C than oranges and also offer the gut-boosting benefits of fiber.

When it comes to immune health, feeding beneficial gut flora might be one of our best tools!

Fully Functional® Probiotics 100 supplements

Probiotics (and Prebiotics!)

I’m often pleased to see that even mainstream health and wellness seems to be catching on to the idea that gut health strongly impacts our overall health. Our immune response begins in our gut, where the cells responsible for attacking external pathogens are created.²

Achieving immune homeostasis, or a state where our immune system can fend off foreign invaders (like that icky strain of flu going around) but doesn’t attack our own cells (as is the case in autoimmunity) requires a difficult balance.

One of the easiest ways to foster this balance is through probiotic and prebiotic supplementation. Probiotic strains pass through our large intestine, what we refer to as our gut, and promote a balance of good bacterial strains.

Our Fully Functional® Probiotics 100 blend is an excellent all-purpose probiotic. If you think your gut health may be disrupted by a pathogen or another imbalance, it’s crucial to begin treating that imbalance as quickly as possible. In these cases I always recommend working with a practitioner to run a gut microbiota test, which may be followed by targeted probiotic therapy.

Your practitioner may also recommend a prebiotic therapy to help “feed” the good bacteria you’re introducing with a probiotic supplement. Prebiotic fibers provide the raw material these bacteria need to thrive. They’re found in prebiotic supplements, but also in cooked and cooled white potatoes, onions, garlic, green bananas, cassava root, and beans (if tolerated).

Balancing gut flora is essential to immune health, and should be a priority if you hope to stay Fully Functional® through the winter!

Fully Functional® Vitamin D supplements

Vitamin D

We refer to this nutrient as a vitamin, but it behaves more like a hormone, with a receptor on immune cells that modulates our immune response. Low levels of vitamin D are associated with autoimmune disease and increased susceptibility to disease.³

Since vitamin D is synthesized on the skin with exposure to sunlight, I find that patients tend to be critically low in this nutrient during the fall, winter, and even spring months (although most patients, especially ones with autoimmune disease, are critically low year-round).

We recommend vitamin D supplementation as the only reliable way to raise levels in preparation for cold and flu systems. This nutrient is so crucial to immune function that it tends to be on even our shortest lists of recommendations. Consider discussing supplementation with your practitioner.

Fully Functional® Glutathione supplement


We addressed the incredible benefits of glutathione in a recent article, Glutathione: Our Most Potent Detoxifier. Maintaining a high level of glutathione is crucial to immune balance.

It regulates our immune systems, and we almost always see depleted glutathione levels in our patients with chronic disease.

Glutathione works by regulating metabolic pathways to help cells control their reaction to oxidative stress, thereby controlling inflammation.⁴ This means glutathione can both stimulate the immune system to fight off disease and down-regulate the immune system in the case of an autoimmune attack.

Clinical trials indicate glutathione may be beneficial in treating a range of diseases from acute infections to diabetes.

elderberries in a bowl


Elderberry is a natural, herbal remedy for the common cold with an interesting body of scientific research behind it.

Researchers believe elderberries have antibacterial and antimicrobial properties, and perhaps more importantly can help modulate our immune response.⁵

In one randomized, controlled study, patients with flu-like symptoms who received a dose of elderberry syrup four times a day reduced their symptom duration by four days and needed less rescue medication than those who received a placebo syrup.⁶

In another double-blind study, air travelers had significantly lower cold durations when given elderberry syrup than those given a placebo.⁷

Elderberry is a fairly inexpensive alternative to over-the-counter cold and flu treatments (an excellent recipe for homemade elderberry syrup is here), and we recommend it as a first line of defense.

Natural Immune Boosters for a Fully Functional® Winter

When kids are in school and cold and flu season looms, it can be tempting to turn to every germ-busting, antibacterial remedy we can think of. But while a clean home can be beneficial, there are more powerful ways to protect our families from a frustrating bout of sickness.

Focusing on these natural immune boosters can help us shore up our body’s defenses without destroying our beneficial gut flora.

Try incorporating vitamins C and D, probiotics, glutathione, and/or elderberry into your routine for a smoother cold and flu season. Make sure to make an appointment at our functional medicine office so we can talk through even more ways to optimize immune function and leave you feeling Fully Functional® for life!

You can book an appointment by clicking here. We are also happy to speak with you at (317) 989-8463, Monday-Thursday, from 8AM – 5PM Eastern time.

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