Why You Keep Getting Sick, and How to Boost Your Immune System | Part 2

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how to boost your immune system

By Dr. Justin Marchegiani

Outside of  taking antibiotics for an infection or Tylenol for a fever, most people don't have many alternatives for how to boost their immune system. There are many immune-boosting supplements out there. My goal is to mention a few supplements that you can use to increase your overall immune function without any side effects.  With a strong immune system, you are less likely to come down with a cold, even if you’re around others who are sick.  These supplements can also be used in lower doses to even help get your immune system ready for the stressful holiday season.

Before you use any of the suggested supplements, I recommend you go back and read part 1 of this post (“Why You Keep Getting Sick, and What You Can Do about Those Flu Symptoms!”) for the foundational lifestyle and dietary advice to boost your immune system. You will need to combine this with the right supplements.  When combined they have synergistic effects and cost you fewer sick days and, at the same time, improve your quality of life.

All of the supplements recommended below are products that I use personally for myself, my family, and my patients. For easy access, I will provide links to the products in our healthy living store.


1. Vitamin D: 

The single best thing you do to boost your immune system is make sure your vitamin D levels are between 60-100 ng/ml.  Your body can produce its natural antibiotic (cathelicidin), which can help your body gobble up intruders.  It can also help balance the immune seesaw above which can help your immune system function better (i.e., increase T-regulator cells).

A 25 OH-D test can be very helpful to assess your levels.   I recommended anywhere between 10, 000-20,000 IU per day for my patients in the winter months, (which is what your body can make in the sun normally).  You need to get a test to find out what your levels are so you can dose according to your body’s needs.  Supplement with liquid vitamin D3. I prefer the liquid emulsified versions best (4). Vitamin D2 is plant based and is not recommended because it doesn't increase 25 OH-D levels as fast and is not typically found in food naturally, like vitamin D3.

Vitamin D3 can be used acutely for 3 days at very high doses to help up-regulate immune function.  The vitamin D protocol has been used by European doctors for many years and is also very safe.

Dosage Instruction

I recommend adding in 75,000 IU of vitamin A and 6 grams of vitamin C at the first onset of sickness.  This protocol packs a potent punch and should do a great job at up-regulating your immune system.

2.  Think twice when you're about to use antibiotics

Sometimes antibiotics may be necessary if you have a bacterial infection that is out of control.  The problem is that antibiotics don’t work on viruses, and they don’t have any effect on strengthening your immune system.  I see many people going on antibiotics year after year when in most situations it was a virus causing the infections to begin with.   The action items in this post actually strengthen your immune system and make your body more resistant to even coming down with these infections to begin with.

3. Avoid the flu vaccine: 

The Cochrane database did a comprehensive meta-analysis on the flu vaccine and found that

“Influenza vaccines have a modest effect in reducing influenza symptoms and working days lost. There is no evidence that they affect complications, such as pneumonia, or transmission.” (1)

According to research, we know that only 10 out of the 200 flu strains are even potentially protected by a flu vaccine.  Said another way, you still have a 90% chance of getting a flu-like illness even with a flu vaccine.  The downside is that the majority of flu vaccines do contain 25 mcg of mercury, which is the second most toxic compound on this planet, right behind uranium (1).  With so many healthy and safe natural options out there, a flu vaccine would be the last option on my list to use.

immune system

4.  Silver: 

This can be a powerful antibiotic and antiviral for preventing illness and can also be used even after you get sick.   Remember, antibiotics can’t touch viruses, so it is nice to have a compound you can use preventively.  You can also use colloidal silver therapeutically.

Let’s say you were around a bunch of sick people this holiday season, and you wanted to prevent any bugs from potentially being passed to you, this could definitely do the trick.  It can be excellent for sore throats, where you can use a spray form and spray the silver directly on the infected area. An acute dosage is 1 tsp 3 time per day. It's very difficult overdose on this product.

5.  Herbal Medicines

Herbs like Echinacea, goldenseal, Andrographis, and Astragalus can be excellent to increase your overall resistance to flu and bacteria that are out to make us sick.  Many studies have done testing on these herbs.  These herbs are most effective when they are used at the early onset of a cold.  The most active properties of these herbs are present in the “roots,” yet many supplements only contain the flower or the stems.  These herbs are shown to up-regulate antiviral, antifungal, and antibacterial activity in the body. They're also shown to increase white blood cell activation as well as natural killer cell activity.

6. Adaptogenic Herbs

Herbs like ashwagandha, rhodiola, Panax ginseng, and licorice are excellent adrenal tonics.  Most of the stress in your body is managed by your adrenal glands; this includes norepinephrine levels, cortisol levels, and sex hormone production. The more stress you're under, the more your body is pushed into a catabolic state. This is where your body is breaking down faster than it can build up. These herbs can help push your body into an anabolic state, where your body can heal faster by reducing cortisol and up-regulating balanced levels of sex hormones

7. Vitamin C

Vitamin C is highly concentrated in your immune cells and can be easily depleted when your body goes into a fever. Upper respiratory infection as well as immune suppression are commonly connected to vitamin C deficiency. Vitamin C also can help buffer the detrimental effects of free radicals. This is where your DNA is damaged. Vitamin C can also help boost the body's level of natural killer cells, your body's first level of  defense. These cells help fight off and destroy any invaders that are trying to enter the body's terrain, similar to the special forces in the military (2).

8. Zinc

Zinc is an important trace mineral involved in over 100 enzymatic processes in the body. Immune suppression and infection are also linked to zinc deficiency.  Zinc can also help improve your enzyme activity and immune-cell function. Your thymus gland, where immune cells mature and are released into circulation, strongly relies upon zinc for optimal function. When your body has less-than-optimal levels of zinc, your thymus function is decreased (3).

9.  Coconut Oil

This is a great antiviral and antibacterial compound.  Coconut oil contains lauric acid, which is a natural substance that is actually found in breast milk, too.  Research has shown that it can kill various forms of strep and staph bacteria.  A few tablespoons of coconut oil per day is good, even if you aren’t sick.

10. Reishi Mushroom Extract

Reishi mushroom (Ganoderma lucidum) has been used for thousands of years and is known as a super herb in both China and Japan. Reishi has immune-boosting, antiviral, anticancer, and liver-protective qualities to name a few (5). It is one the most studied of all the mushrooms and contains specific polysaccharides that are clinically proven to reestablish white blood cell levels.

Reishi mushrooms also contain other immune-boosting compounds known as ganoderminc acids or triterpenes. Triterpenes are proven to inhibit viruses, including HIV, by up to 50% (6, 7). If your are going to use reishi to enhance your immune system, you want to make sure you are using a reishi product from a reputable company that has at least a 10% polysaccharide and 4% triterpene content for maximal benefit.

11. Astragalus Extract

Astragulus root is a potent herb used in traditional Chinese medicine. It has many immune-boosting benefits, including, enhancing the growth of spleen cells to help destroy foreign invaders and the up-regulation of natural killer cells (the first line defense of the immune system). It also has antiviral properties.

Astragalus can increase antibody production, including IgM and IgE ab. It can also help increase mucosal immunity by boosting nasal secretions of IgA and IgG as well (8). Astragalus and reishi can work synergistically together and are safe immune-boosting compounds to take on a daily basis. These herbal medicines are the first thing I grab out of my medicine cabinet if I am feeling under the weather.

Combined with the diet and lifestyle principles from my first post, I hope these recommendations help improve your chances of not getting sick this winter season.

Preventative Protocol

  1. Consume at least 0.5 g of protein per pound of body weight every day. This will ensure that you are getting your minimum daily intake of protein.
  2. Vitamin D: at a minimum 2000 IU per day should be used. I recommend getting a 25 OH-D test to see if higher levels are needed.
  3. Vitamin C: 1000 mg per day.
  4. Adaptogenic herbs: 1 gram of ashwaganda, 600 mg of rhodiola, 500 mg of eleuthero.
  5. Immuno Supreme: 2 capsules with breakfast.

Acute Protocol (Take at first sign of sickness!)

  1. Echinicea Angustifolia tincture: 1 tsp 3-4x per day.
  2. Epson salt bath: 2x per day to the point of sweating.
  3. Vitamin C: 2,000 mg 3-4x per day.
  4. Astragalus: 2 capsules every hour.
  5. Silver: 1 tsp every hour.
  6. Immuno Supreme: 2 capsules every two hours.
  7. Reishi mushroom: 500 mg every hour.
  8. Ginger tea recipe.
  9. Vitamin D: follow the high-dose vitamin D protocol above for 6 days.
  10. Listen to your body and get some rest!

If you need more help to boost your immune system back on track, click here!


1. Jefferson T. Vaccines for preventing influenza in healthy adults. Cochrane Database of Systematic Reviews 2010.

2. Vitamin C may affect lung infections. J R Soc Med. 2007 November; 100(11): 495–498.

3. Anuraj H Shankar and Ananda S Prasad. Zinc and immune function: the biological basis of altered resistance to infection1–3.

4. Bikle DD. Curr Osteoporos Rep. Vitamin D and immune function: understanding common pathways. 2009 Jul;7(2):58-63. 

5. Nutr Cancer. 2010: Triterpenes from Ganoderma Lucidum induce autophagy in colon cancer. 

6. Bioorg Med Chem Lett. 2011. Triterpene derivatives that inhibit human immunodeficiency virus type 1 replication.

7. Lipids. 2001.Inhibitory effects of triterpenoids and sterols on human immunodeficiency virus-1 reverse transcriptase. 

8. J Ethnopharmacol. 2007 . In vitro and in vivo immunomodulating and immunorestorative effects of Astragalus membranaceus.

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