Is Your Immune System Susceptible or Strong?

By January 28, 2021Dr. Meletis

By Chris D. Meletis, N.D.

Whether or not we contract a virus, bacteria, or other pathogen depends on our individual  susceptibility. So what makes someone more susceptible to becoming ill? Some people can  have genetically healthier immune systems or better control over their inflammatory  responses. However, studies show that external factors impact immunity more than genetics  does.1 For example, environmental toxin exposure, psychological stress, obesity, lack of  restorative sleep, and dietary intake of nutrients all can keep your immune system from  functioning at its best.2 All of these factors cause what’s called allostatic overload.2 Allostatic  load refers to the ways in which your body remains in balance. Anything that overtaxes your  allostatic load can throw you and your immune system out of balance. 

The good news? There are certain ways to improve your immune system naturally. Here are  some easy suggestions on how to support immunity. These are especially useful in the winter  when we’re confronted by many different immune assaults. However, they can be used all year  long with good results. In fact, the lifestyle strategies should be something you do throughout  the year to keep you healthy all year long.

The Most Effective Lifestyle Strategies

First, avoid exposure to toxins, which includes pollution. Toxins can reduce immunity and push your body into a hyperinflammatory state.3-6In addition, obesity can lead to weakened lung  function, so it’s important to take steps to stay at a healthy weight.7 Getting a good night’s rest  is also important. Not getting enough sleep is linked to weakened immune system function and  weakened immune cells such as CD4+ and CD8+ T lymphocytes and natural killer cells.8,9

One reason for poor sleep is exposure to light at night, which deprives lots of people of a deep,  restful sleep. Exposure to light at night also causes levels of melatonin to drop. Melatonin is an  antioxidant and anti-inflammatory that may enhance respiratory health and boost  immunity.10,11 Therefore, it’s important to reduce your exposure to light at night. 

How To Support Immune System Health 

Studies show that a number of botanicals, vitamins, and other nutrients have a role to play in  supporting immunity. I always recommend to my patients that they keep these ingredients on  hand so they’ll have them when they need them. I like to recommend Tru Immune Support,  because it conveniently contains all these effective ingredients in one supplement, along with  Tru D3 to make sure your vitamin D3 is at healthy levels.


Astragalus is well known for its ability to provide immune system support. It offers a helping  hand to the immune system by improving the function of natural killer cells and reducing  activity of proteins known as pro-inflammatory cytokines.12,13 It also enhances the activity of  lymphocytes, white blood cells responsible for antibody production.14

Yeast-Based Fermentate (EpiCor®)

EpiCor® is made from a type of yeast (Saccharomyces cerevisiae) that boosts immunity. In  preclinical and human studies, EpiCor® improved mucosal immunity, supported the health of  people with seasonal allergies, supported a healthy inflammatory response, and helped people  under the weather feel better.15-17


Preclinical and cell culture studies show berberine may support immune health. In mice, it  supported a healthy inflammatory response in the lungs.18 In both human cells and in mice,  berberine blocked viral replication.19,20

Olive Leaf Extract

Olive leaf extract is loaded with polyphenols that keep the immune system and respiratory tract  healthy. Olive leaf extract promotes immune health by interacting with the protein of virus  particles, weakening virus actions.21 It also stimulates the production of natural killer cells.22 In  a randomized, placebo-controlled study of 32 high school athletes, olive leaf extract supported  upper respiratory tract health.23 One of the most important components of olive leaf is  oleuropein. Tru Immune Support contains olive leaf extract with a generous 16% oleuropein for  optimal potency. 

Vitamin C and Zinc

These two foundational nutrients are critical for immune health. A meta-analysis of the medical  literature found that vitamin C supported the health of 11,077 people who had the common  cold.24 Dietary zinc also plays an important role in immunity. Even a mild deficiency of this  mineral can weaken the function of immune cells.25 Zinc supplementation can promote  immune health in people exposed to wintertime immune system challenges. Researchers have  recommended the use of zinc supplements to counteract modern-day immune threats.26 This is  because zinc enhances innate and acquired immune responses.26 It can also shield cells from  viral entry and replication.26


This herb contains allicin, garlic’s active component that was shown in a human study to keep  subjects healthy.27 Even in the subjects that didn’t feel their best, garlic supplementation made  them feel better faster. Furthermore, research has shown that garlic essential oil acts on the  angiotensin-converting enzyme 2 (ACE2) protein.28 ACE2 is involved in cellular immune  defense.28

Citrus Bioflavonoids

Citrus bioflavonoids are immune-promoting compounds that come from citrus fruits such as  oranges and lemons. In particular, the citrus bioflavonoid hesperidin has immune-boosting  abilities.29,30 Citrus bioflavonoids team up with vitamin C to enhance immune health. 

N-Acetyl Cysteine (NAC)

This antioxidant has several useful abilities. First, it breaks up mucous and clears the respiratory  passages.31 Second, it supports lung health.31 Human research has found NAC can significantly  support immune system health and lung function at times when immune support is needed the  most. 32

Vitamin D3

Vitamin D3 is an important player in immune health. A systematic review and meta-analysis of  the medical literature including 25 randomized, controlled trials of 11,321 people found that  vitamin D supplementation improved respiratory tract health in all the study subjects.33 The  beneficial effects were most evident in the people with vitamin D deficiency. Healthy vitamin D  levels are also linked to better immune function, reduced levels of inflammatory cytokines, and  good respiratory function.34-36

Cannabidiol’s Role in Immune Health

Many people don’t think about Cannabidiol (CBD) in terms of enhancing immunity. However,  research is unveiling possible ways CBD may be involved in immune health. CBD works through  what’s known as the endocannabinoid system. This system includes receptors like CB1 and CB2  and endocannabinoids that your body produces that work on these receptors. Sometimes, due  to factors like psychological stress, people can suffer from endocannabinoid deficiency, where  they’re not producing enough endocannabinoids or the system simply doesn’t work the way it  should. This can lead to problems in many areas of health, including immunity.37

The evidence that CBD can play a role in keeping the immune system healthy begins with the  fact that immune cells express the CB2 receptor and to a lesser extent CB1.38 However, CBD  also works through other receptors that are related to the endocannabinoid system, although  not directly a part of it. For example, CBD activates transient receptor potential vanilloid 2  (TRPV2), a protein that plays a role in healthy immune system function.39 What’s more, CBD  enhances the action of natural killer cells.40

CBD can also soothe the inflammatory response in the gut, where much of the immune system  is located.41 In addition, by reducing the production of inflammatory cytokines and promoting a  healthy inflammatory response, CBD keeps the lungs and respiratory tract healthy.42-46 Finally,  CBD has a calming effect that reduces stress.47 Psychological stress is associated with reduced  immunity.48

The Bottom Line on Immune System Support

One of the most important considerations as to whether or not you stay healthy is how  susceptible you are. To summarize the points in this article:

• Make sure to regularly get restorative sleep in a dark room.

• Detoxify your body of toxins and avoid toxin exposure in the first place to keep your body  from becoming overburdened.

• Take steps to remain at a healthy weight.

• Promote immune system health by using Tru Immune Support, which contains the ingredients  mentioned in this article. 

• Add Tru D3 into your supplement routine to take advantage of vitamin D3’s ability to support  immune health.

• Finally, as an additional way to power up the immune system, add CBD to your supplement  routine. 


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