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Essential Immune Boosting Supplements

What causes some of us to succumb to every cold or flu we come across while others are lucky enough to stay healthy with seemingly little effort? A healthy lifestyle and a strong immune system are important factors in your ability to fight off infection and disease. Most of us would benefit from taking steps to improve our immune systems. At TCIM, we want to help you reach your optimal health. To assist you, we are providing this series of articles that explain how your immune system works and ways to make it stronger.

Essential Immune Boosting Supplements

In the first article, we discussed the 5 Pillars of Health, which encompass five aspects of life that need to be cared for in order to maintain optimal health. If any area is neglected, the others are also weakened, allowing an opportunity for illness and chronic disease. We also explained ways that you can improve your health in each area.

The second article contained a very brief overview of the components of your immune system, how they work, and why they are vital to your health. We also explained ways that the 5 pillars of health impact specific areas of your immune system. This article is helpful in understanding enough about the immune system to comprehend the rest of this series.

5 goals to strengthen your immune system were the focus of the third article. Each of these five goals targets the immune system in specific ways and we explained how each goal works and provided a few tips to support each goal.

In this article and the rest of the series, we are going to provide you with information on specific supplements that help your immune system prevent or treat illnesses. In addition to recommendations, we will supply resources and scientific references that provide evidence that each supplement is safe and effective, so you can feel confident that you are choosing the best, proven support for your immune system.

Please note that all recommendations should be read with the understanding that they are recommendations to help strengthen one’s immune system and support the body in eliminating environmental toxins through natural means. Additionally, if you are pregnant or breastfeeding, or have a chronic health condition, it is important to check with your provider before adding or increasing the amounts of any vitamin, supplement, or immune-boosting product.

Our immune boosting prevention kit includes three essentials: vitamin D3, vitamin C, and probiotics with Saccharomyces boulardii. We recommend that you also consider beta-glucan and melatonin.

Vitamin D3

Sufficient amounts of vitamin D3 are critical because, not only does it help you absorb calcium, it is also necessary for healthy immune function. In fact, Vitamin D deficiency can cause you to be more susceptible to infection and autoimmune disease. Vitamin D plays an important role in the innate antimicrobial response and has numerous effects on various cells in the immune system. These effects result in decreased production of inflammatory cytokines and increased production of anti-inflammatory cytokines (1). This is an important function in moderating the inflammatory response. Clinical trials have provided strong supportive evidence that individuals who took high levels of vitamin D were protected from influenza during the winter season (2, 3).

Vitamin D3 is the nutrient that our bodies produce when exposed to sunlight. We can also get it from foods that come from animals. Fatty fish are the best food source, although eggs and cheese also have a bit. Eggs from pasture-raised chickens have much higher amounts of vitamin D3. You can get vitamin D2 from some plant sources and fortified foods, but studies have shown that vitamin D3 is more bioavailable, which means that our bodies use it more effectively than D2 (4, 5).

Unfortunately, if you get very little sunlight it is difficult to consume enough vitamin D3 from food sources. For this reason, many people are deficient in this essential nutrient and need to take a supplement to maintain optimal immune health.

Be careful not to consume large quantities, unless under a doctor’s supervision. This nutrient is fat-soluble, which means that you can consume toxic amounts. It also remains in your body for quite a while. If you take too much in one week, it will stay in your body for about 6 weeks. Luckily, your body cannot produce too much if you are in the sun too long. You can only get toxic amounts through overdosing on supplements.

Essential Immune Boosting Supplements

Vitamin C

Vitamin C supports the innate and adaptive immune system in many ways, including supporting the barrier defense, phagocytosis, and reducing tissue damage (6). When the immune system responds to a virus it creates a lot of free radicals. Vitamin C helps neutralize free radicals and reduce tissue damage caused by an excess of free radicals (7, 8). It has also been proven to prevent and treat respiratory infections and reduce the duration of the common cold (6, 9, 10).

Although vitamin C is abundant in many fruits and vegetables, vitamin C deficiency is the fourth greatest nutrient deficiency in the United States (11). This is partly due to the fact that many factors can increase your requirement for vitamin C. Aging, illness, smoking, exercising, and living in polluted areas can increase your requirement. For example, when a person has a cold, 8 grams a day (8,000 milligrams) has been found to shorten colds by 19% (10) without adverse effects. That is far greater than the recommended 65-90 milligrams per day for healthy adults.

Since vitamin C is not a nutrient that stays in your body for long, it is important to consume it at regular intervals throughout the day. In the unlikely event that a megadose results in too much vitamin C, the most common side effect people experience is temporary diarrhea or nausea. Not all vitamin C supplements are created equal. Pure and augmented formulations are absorbed better (12), and some are gentle on the stomach.

Probiotics with Saccharomyces boulardii

There is an abundance of evidence showing that probiotics enhance the immune system and reduce the incidence of infection from cold and flu viruses in adults and children (13, 14, 15, 16, 17, 21, 22). Probiotics contribute to a healthy microbiome, which is essential for your immune system and lining of the gut to flourish. Without a healthy gut microbiome, your immune system, gastrointestinal tract, and respiratory system will not function and ward off infection as well, you are more likely to experience food and respiratory allergies, and you will not absorb nutrients as effectively (18, 19). Additionally, if your immune system is already weakened due to an unhealthy, imbalanced gut, it will have fewer resources to fight a cold or flu.

Some fermented foods are a great source of probiotics. Yogurt, sauerkraut, kefir, kombucha, pickles, miso, tempeh, kimchi, and some cheeses often contain probiotics. However, if you are purchasing these foods at the store, be sure that they contain live and active cultures.

If you prefer to take probiotic supplements, we recommend that your probiotics include Saccharomyces boulardii. It has been proven effective at treating and preventing several gastrointestinal diseases, and “mediates effects which resemble the protective effects of the normal healthy gut flora” (20). These effects also help balance your microbiota and immune system.

Beta Glucan

Beta Glucan is a soluble fiber that occurs naturally in yeast, certain cereal grains, seaweed, algae, and reishi, maitake, and shiitake mushrooms. Beta glucans are widely used for many conditions including high cholesterol, diabetes, cancer, and HIV/AIDS, and are even used to prevent infection after surgery. They modulate and strengthen the innate and adaptive immune responses and may even help your body defend against the harmful effects of stress (23, 24).

Over 50 years of scientific research has proven that beta glucans are important to human health. Many people would benefit from supplementing this important soluble fiber, especially those on a low-carb diet.

If you have Lyme disease, lupus, multiple sclerosis, rheumatoid arthritis, asthma, inflammatory bowel disease, or other chronic conditions be sure to check with your doctor before taking beta glucan supplements. Beta glucan may not be right for you, or you may need a lower dose.


Sleep is one of the five pillars of health. If you regularly go without enough sleep your health will eventually suffer. Your immune system requires sleep to function well. Without enough sleep, you are more likely to experience symptoms after exposure to a virus and take longer to recover (25, 26).

Unfortunately, getting regular, good quality sleep is not as simple as it should be. This is when supplementing with melatonin becomes useful. In addition to helping you become better at sleeping, melatonin is a powerful antioxidant (27) and anti-inflammatory molecule and has beneficial effects on the immune system. It protects against acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) caused by viral and other pathogens (28).

Unlike other supplements, melatonin does require a bit of intentionality when you take it. It is important to take it about 30 minutes before you want to sleep, then go lie down in a dark room. If you take melatonin then expose yourself to light, even a darkened phone or dim reading light, it will not be effective.

In Conclusion

These 5 supplements make up our immune-boosting prevention kit, but what about if you are already ill, or fighting off a virus? There are quite a few more supplements you can take in that situation in addition to these five, and we will discuss those in the next article.

If you want help deciding what supplements are right for you, what dose you need, or which brands are reliable, we are privileged to help. Our Functional Nutrition Lifestyle Practitioners are here to help you develop a nutrition plan to begin incorporating natural sources of the nutrients you need into your daily lifestyle. Please feel free to call us to make an appointment. If you just want to place an order through us, you can call the office or click here to order directly. Stay safe and healthy!


Jonathan Vellinga, M.D.

Jonathan Vellinga, M.D. is an Internal Medicine practitioner with a broad interest in medicine. He graduated Summa cum laude from Weber State University in Clinical Laboratory Sciences and completed his medical degree from the Medical College of Wisconsin.​

Upon graduation from medical school, he completed his Internal Medicine residency at the University of Michigan. Dr. Vellinga is board-certified with the American Board of Internal Medicine and a member of the Institute for Functional Medicine.



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