How to Make Your Immune System Stronger

11/04/2021 | 15 min. read

Dr. Stephen Sinatra

Dr. Stephen Sinatra

To guard against viral infections, we’re told to wash our hands, avoid touching our eyes and mouth, and stay away from people who are ill. These are all good suggestions, but there’s one glaring omission—advice on how to support your immune system. 

We are constantly exposed to viruses, bacteria, and other infectious microorganisms, but most of us rarely get sick. Why? Because our immune systems are working 24/7 to keep us healthy. 

Before we jump into specific recommendations for enhancing immune function, let’s briefly review how the immune system works. 

Innate vs. Adaptive Immune System

The innate immune system is your body’s frontline defense. It includes your skin, mucous membranes, and the substances they secrete, which form a protective barrier to keep out infectious microbes and other pathogens.

When germs get past these physical barriers—through, for example, close contact with someone who has a viral infection—the innate immune system releases immune cells and proteins that rapidly get to work. They include: 

  • Phagocytes: These white blood cells scavenge, engulf, and “digest” viruses and other microbes. 
  • Enzymes: Enzymes are proteins that speed up the immune response, target germs, attract other immune cells, and directly attack bacteria and viruses.
  • Natural killer (NK) cells: NK cells are lymphocytes, which are another type of white blood cells, that detect, target, and destroy infected or cancerous cells.

Innate immunity, which is active even before birth, is also called nonspecific immunity because it responds to general threats and uses the same tools to repel all types of pathogens. If infectious organisms or abnormal cells remain after this initial onslaught, the adaptive immune system comes into play. 

What Is the Adaptive Immune System? 

Adaptive immunity, also referred to as specific or acquired immunity, is the “educated” aspect of your immune system. It first identifies infectious microbes, then deploys specific immune cells to dispatch them. The adaptive immune system works more slowly than the innate immune system, which is on constant alert, but it is more precise and accurate. The primary players in the adaptive immune system are T and B lymphocytes:

  • T cells: T cells identify infected and abnormal cells, activate the adaptive immune response, multiply, and destroy pathogens.
  • B cells: Activated by T cells, B cells produce antibodies to specific antigens (microorganisms and other substances that trigger the creation of antibodies). 
  • Antibodies: Antibodies circulate in the blood, attach to target antigens, and neutralize or mark them for destruction. They also support the innate immune system.

T cells, B cells, and antibodies all help your adaptive immune system “remember” pathogens from prior infections. This allows for a quicker response the next time those germs are encountered. It’s also why you develop immunity to certain diseases once you’ve been infected. 

What Are the Best Supplements for Immune Health? 

You don’t need me to tell you that a healthy lifestyle is indispensable for all aspects of health. You already know the importance of regular exercise, restful sleep, stress management, and a good diet with adequate protein, healthy fats, and lots of high-fiber plant foods to boost your immune system. 

What many people are unsure of—and this is something I am often asked about—are the best supplements for bolstering immune function and protecting against viral infections. There are so many immune products out there and so much conflicting information that it’s hard to know what to believe. 

I am a cardiologist, and I don’t claim to be an expert in infectious diseases. However, I have always kept up on the latest scientific research on vitamins, minerals, probiotics, and herbs for immune system support. Here’s what I recommend.

A Potent Multivitamin Is Essential

I believe everyone should take a daily multivitamin and mineral supplement. The nutrients in multivitamins are not produced by the body, so the only way you can get them is in food or supplements—and many of them are critical for immune function. The micronutrients in a multi that are particularly important for your immune system include:

  • Vitamin C: This vitamin has a well-deserved reputation as an immune booster. Studies have shown that, when taken at the first signs of a cold or other viral respiratory infection, vitamin C reduces the duration and severity of symptoms. The recommended daily dose is 400–1,000 mg, increasing to 400–500 mg every few hours if you feel a bug coming on. 
  • Vitamin D: An extensive meta-analysis by a group of international researchers revealed that supplemental vitamin D protects against acute respiratory tract infections. A good multi should contain at least 1,000 IU (25 mcg) of vitamin D. Unfortunately, that may not be enough to maintain an optimal vitamin D blood level of 50-75 nmol/L. Talk to your doctor about testing and take extra, if needed.
  • Zinc: This mineral supports the integrity of the skin and mucous membranes, which are the sentries of the innate immune system. Deficiencies in zinc also dampen the activity of NK cells and increase susceptibility to viral infections. Your multi should have a minimum of 15 mg of zinc.
  • Other antioxidants: Vitamin A also supports the skin and mucous membranes and helps stave off pathogens. Vitamin E protects against oxidative stress and inflammation in the respiratory system and other tissues. Selenium inhibits the replication of some viruses, boosts glutathione levels, and supports overall immune function. Some multis also contain extracts from cranberries pomegranates, goji, mangosteen, and other botanicals with potent antioxidant properties. Recommended doses are vitamin A 1,500 mcg RAE, vitamin E 67 mg with mixed tocopherols, and selenium 100 mcg.

Support Your Gut Microbiome

Did you know that most your body’s immune cells are in your gastrointestinal (GI) tract? And that the bacteria that reside there—the gut microbiome or microbiota—are a key regulator of immunity? 

As reported in a recent study published in the BMJ journal Gut, “...the GI tract is the largest immunological organ in the body and its resident microbiota are known to modulate host immune responses…”

Gut bacteria produce metabolites that increase the activity of phagocytes and T cells, modulate the production of cytokines and other inflammatory mediators, and suppress the growth of harmful microorganisms. Thousands of scientific studies stress the importance of a diverse, well-balanced gut microbiome.

You can support your gut microbiome by eating fermented foods, which contain bacteria species that support a healthy GI tract. Dietary fiber is of utmost importance, as gut microbes feed on fiber. Bacterial diversity requires a variety of fibers from vegetables, fruits, and whole, unrefined grains—fiber supplements alone won’t cut it. You also need to avoid sugar, as it has detrimental effects on the gut microbiome. 

I strongly recommend supplemental probiotics as well. There has been an explosion of research on probiotics in recent years, and multiple species have been found to support the immune response. For instance, Floradapt’s L.plantarum KABP ™-031 and L.plantarum KABP™-032 help regulate the adaptive immune system, reduce inflammation, and promote a healthy immune response.

Several other strains of Lactobacillus as well as Bifidobacterium, Faecalibacterium, and Eubacterium also have proven benefits. Look for a high-potency probiotic from a reliable manufacturer.

Additional Recommendations

Beta-glucan, a polysaccharide in some grains and fungi, primes phagocytes, NK cells, and innate immune system activity. Andrographis, which is a standard in Ayurvedic medicine, also stimulates the activity of phagocytes and NK cells to help fight off foreign invaders. Cat's Claw, extracted from a vine native to Peruvian rainforests, blocks inflammatory pathways that go into overdrive during infections. Elderberry is another botanical that has anti-inflammatory as well as antioxidant activity.

I am also keen on quercetin, which helps restore antioxidants in the lungs; compounds in oil of oregano that protect against influenza and other respiratory viruses; astragalus, an adaptogenic herb that supports lung function; and N-acetyl Cysteine (NAC), a potent antioxidant that helps clear mucus from the airways and has been shown to reduce the severity and duration of flu-like symptoms.

Last but not least, I recommend coenzyme Q10 (CoQ10). In addition to its essential roles in energy production and cardiovascular health, CoQ10 also supports your immune system. Clinical data has demonstrated that it not only curbs oxidative stress but also helps combat inflammation via its effects on powerful inflammatory mediators such as IL-6, CRP, and NF kappa-B. CoQ10 is especially important in light of the infectious microbes that we are facing every day.

I am not suggesting you take all these products. A basic regimen—a probiotic with proven bacterial strains, plus a potent daily multivitamin and mineral supplement with extra vitamins C and D and CoQ10—is sufficient for most people. 

If you are looking for extra immune support due to age, medical conditions that put you at greater risk, or simply for peace of mind, you may want to fortify your program with some of these other proven supplements. Whatever you do, be proactive about immune support.

Dr. Stephen Sinatra

Meet Dr. Stephen Sinatra

Dr. Stephen Sinatra is a highly respected and sought-after cardiologist and nutritionist with more than 30 years of clinical practice, research, and study. His integrative approach to heart health focuses on reducing inflammation in the body and maximizing the heart's ability to produce and use energy.

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