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The 5 Best Peptides for Boosting the Immune System

One of the most critically overlooked parts of fully optimized health is your immune system.

This invisible yet always-active biological network protects us from bacteria, viruses, germs, and other harmful pathogens.

But it’s unrealistic to expect it to run at 100% 24/7, especially as we get older.

And sometimes even healthy people need an immunity boost to fight off diseases that kick our ass out of nowhere.

Which is why I want to focus on therapeutic peptides for immune system repair and enhancement.

Just like we have peptides specifically designed to make us smarter, younger-looking, and leaner

…we also have peptides that stop us from getting sick.


What are the Signs of a Strong Immune System?

Before we can start using peptides for boosting our immune system, we have to understand what a strong immune system looks like.

The best way to do this is look at the characteristics of a weak immune system:

  • Chronically elevated stress levels and poor adaptation to said stress
  • Slower-than-usual healing time for wounds
  • Frequently battling infections and dealing with a longer recovery process
  • Constantly catching colds
  • Often suffering from digestion problems (diarrhea, gas, constipation)
  • Feeling chronically tired 24/7
  • High levels of inflammation

Knowing the information above, we can reverse them to get a picture of a strong immune system:

  • Stress levels are low and manageable
  • Faster healing of wounds
  • Rarely battling infections, and experiencing very slightly symptoms when you do get ill
  • Colds rarely happen and aren’t noticeable
  • No digestion problems (i.e. healthy and frequent bowel movements)
  • Feeling energetic during the waking hours of the day
  • Low levels of inflammation

But even outside of these somewhat subjective criteria, there are numerous biomarkers we can measure to objectively evaluate our immune system health.

(Yet another reminder of how important it is to get regular blood work done!)

Keep in mind our immune system is composed of two distinct sub-systems, one acting as the first line of defense and the other acting as the second line:

The innate immune system provides a general defense against harmful germs and substances, so it’s also called the non-specific immune system. It mostly fights using immune cells such as natural killer cells and phagocytes (“eating cells”).

The main job of the innate immune system is to fight harmful substances and germs that enter the body, for instance through the skin or digestive system.”

“The adaptive (specific) immune system makes antibodies and uses them to specifically fight certain germs that the body has previously come into contact with. This is also known as an “acquired” (learned) or specific immune response…the body can also fight bacteria or viruses that change over time.”

This is separate from “autoimmunity”, where our own immune system will mistakenly target the body’s healthy cells and tissues… often times as much if not more than the foreign pathogens invading the body.

Can Peptides Boost the Immune System?

First, it’s important to remember that using peptides for immune system fixes will not permanently reverse the inevitable age-associated decline of immunity:

“Beginning with the sixth decade of life, the human immune system undergoes dramatic aging-related changes, which continuously progress to a state of immunosenescence.

The aging immune system loses the ability to protect against infections and cancer and fails to support appropriate wound healing. Vaccine responses are typically impaired in older individuals.

Conversely, inflammatory responses mediated by the innate immune system gain in intensity and duration, rendering older individuals susceptible to tissue-damaging immunity and inflammatory disease.”

(Not to mention this decline is far more pronounced in men than women)

And that’s not even getting into the lifestyle factors that weaken our immune system: Biological/environmental toxins, low testosterone levels, smoking, alcohol, poor sleep, low Vitamin D levels / lack of sunlight, crappy diet, and so on.

But going back to the discussion at hand, it’s been well established over the past 40 years that our body’s naturally-produced peptides are a major part of the initial immune response:

“…innate immunity is the first line shotgun approach of defense against infections and is exemplified by antimicrobial peptides (AMPs), also known as host defense peptides (HDPs).

HDPs are traditionally thought to be broad-spectrum antibiotic peptides that do not confer long-lasting or protective immunity to the host.

…these peptides also have immunomodulatory activities, for instance in suppressing proinflammatory cytokines, which can more readily explain their ability to treat microbial infections.”

Emerging evidence also suggests these AMPs (anti-microbial peptides) play a role in adaptive immunity, and may be pro-inflammatory or anti-inflammatory:

“They act on B-lymphocytes indirectly, enhancing the induction of antigen-specific immunity, which ultimately leads to the activation of adaptive immunity. 

For the successful use of AMPs in medical practice, it is necessary to study their immunomodulatory activity in detail, taking into account their pleiotropy… since AMPs can suppress inflammation in some circumstances, but aggravate the response and damage of organism in others.

It should also be taken into account that the real functions of one or another AMP depend on the types of total regulatory effects on the target cell, and not only on properties of an individual peptide”

Not only are these AMPs constantly expressed, but they are also implicated in rheumatic arthritis, Chrohn’s disease, and other autoimmune conditions.

Going even further, we even see whey proteins/peptides showing beneficial effects on the immune system.

(Yes, the same whey proteins you consume in the form of a protein shake immediately post-workout to keep muscle protein synthesis going)

So it’s not a question of whether we can peptides for immune system repair, but HOW we can use them selectively to strengthen our immunity and stay protected from harmful pathogens.

How Peptides Strengthen Immunity

The best peptides for your immune system aren’t so much “boosters” as they are regulators of immunity.

In other words, peptides for immunity help maintain an optimal balance of immune cells in the body (i.e. homeostasis) via the stimulation or suppression of the body’s immune response. 

This is why you’ll often see peptides referred to as “immuno-modulating agents” when you look them up in the medical literature.

Many of these peptides are naturally found in your body and can be re-administered into your system exactly as they are if you know how to make them properly.

Other peptides are synthetically created but are close analogs of what already occurs naturally.

But no matter how they’re made, peptides can regulate your immune system in the following ways:

All we’re doing is making your body far more effective and efficient at what it already does without outside assistance.

Whether you take these peptides in the form of an injection or nasal spray, people often see results anywhere between a few days to a few months (depending on the nature of their condition).

But thanks to the nature of therapeutic peptides in general, their side effects are next to none in severity or frequency.

Their effects will be far more pronounced in people who are recovering from illness and disease versus those who do not have any outstanding health issues.

The 5 Best Immune-Boosting Peptides

There are only 5 peptides for immune system regulation that I would recommend.

Fortunately, most of them either target immunity solely or have immune system modulation as one of their primary effects.


LL-37 is a peptide spanning 37 amino acids that is directly derived from an antimicrobial peptide called “cathelicidin”.

A cathelicidin is a “cationic antimicrobial peptide (AMP) in which a highly conserved N-terminal structural domain, cathelin, is linked to a C-terminal peptide with antimicrobial activity” (Source)

To be more exact, LL-37 is derived from the region of the only known human cathelicidin to exist (a.k.a. hCAP18) that has antimicrobial properties.

This peptide works mostly through binding to the pathogen’s cellular membrane and leaking out the contents within the pathogen’s cell, ultimately leading to cellular death.

The benefits of LL-37 can be summed in three words: Anti-bacterial, anti-fungal, and anti-viral.

LL-37 has often been lauded as a possibly superior treatment option compared to antibiotics based on its broad spectrum activity and lower levels of treatment resistance without harming the host organism.

However, the COVID-19 pandemic saw LL-37 re-emerge as a possibly effective therapeutic:

“SARS-CoV-2 infection begins with the association of its spike 1 (S1) protein with host angiotensin-converting enzyme-2 (ACE2). Targeting the interaction between S1 and ACE2 is a practical strategy against SARS-CoV-2 infection. Herein, we show encouraging results indicating that human cathelicidin LL37 can simultaneously block viral S1 and cloak ACE2” (Source)

“We hypothesize upregulation of LL-37 will act therapeutically, facilitating efficient NET clearance by macrophages, speeding endothelial repair after inflammatory tissue damage, preventing α-synuclein aggregation, and supporting blood-glucose level stabilization by facilitating insulin release and islet β-cell neogenesis. In addition, it has been postulated that LL-37 can directly bind the S1 domain of SARS-CoV-2, mask angiotensin converting enzyme 2 (ACE2) receptors, and limit SARS-CoV-2 infection. “ (Source)

Long story short: LL-37 can be considered your go-to anti-bacterial and/or anti-viral solution, especially in the very early days of infection.


Vasoactive intestinal peptide (VIP) was initially discovered in the 1960s as a vasodilator that is produced in numerous parts of the human body.

Indeed, it is very good at reducing high blood pressure, improving oxygenation (i.e. getting oxygen from the lungs and pushing it throughout the body), and relaxing the larger airway passages within the lungs.

But within its long laundry list of health benefits, you’ll also find its simultaneous involvement in both innate and adaptive immunity.

So on top of activating the cells needed to prevent pathogen movement within the body, it can also activate the cells needed to generate immunity to a specific pathogen.

And when it comes to COVID-19, more VIP production reduces your chances of suffering from severe illness:

“…plasma levels of the immunoregulatory neuropeptide VIP are elevated in patients with severe COVID-19, correlating with reduced inflammatory mediators and with survival on those patients.

In vitro, vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP), highly similar neuropeptides, decreased the SARS-CoV-2 RNA content in human monocytes and viral production in lung epithelial cells, also reducing cell death.”

And especially for COVID-19 patients suffering from severe comorbidities, VIP can be used as a treatment to increase survivability and recover fully from respiratory failure.

Put another way: If VIP production is blocked by COVID-19, you will find yourself unable to breathe and needing a ventilator (effectively a death sentence).

VIP is recommended for general immunity but is especially useful as the “magic bullet” against any illness involving respiratory problems and/or lack of blood flow.  


TB-500 is the active region of a naturally-occurring peptide in your body called Thymosin Beta-4 (Tβ4).

Tβ4 is what gets secreted by your thymus gland immediately after your body gets injured, but your body can only produce so much of it.

That’s when scientists had the idea to isolate the region of Tβ4 that was solely responsible for its healing effects.

And the two ways in which this happens are through angiogenesis (new blood vessel formation) and actin production (which maintains and restores a cell’s physical structure).

While TB-500 is phenomenal for healing just about any kind of injury under the sun — anything from tissue to skin wounds — its repair ability can also extend to the immune system.

This is true when you consider that Tβ4 comes from a family of peptides produced in the thymus that are “known to activate the immune system through several mechanisms and signaling pathways, including stimulation of T cell differentiation and maturation, activation of NK cells, DCs, and induction of proinflammatory cytokine release” (Source).

In the case of COVID-19, there is one postulated mechanism for how TB-500 could be useful:

“…an increase of fibrinolysis could be achieved by increasing ACE, or by administering Tβ4. Fibrinolysis is the breakdown of fibrin in blood clots and Tβ4 has been shown to prevent actin from binding to fibrin, which is a major component of blood clots.  Blood clots in the blood stream and organs of patients with COVID-19 have been shown to lead to extensive morbidity and patient death”

And a 2021 mouse study found that TB-500 is perhaps worth testing more thoroughly in humans who have COVID-19:

“Tβ4 regulates actin polymerization and functions as an anti-inflammatory molecule and an antioxidant as well as a promoter of wound healing and angiogenesis. These activities led us to test whether Tβ4 serves to treat coronavirus infections of humans.

… We found that [TB-500] significantly increased the survival rate of mice infected with MHV-A59 through inhibiting virus replication, balancing the host’s immune response, alleviating pathological damage, and promoting repair of the liver.”

TB-500 is what I would go for if your illness revolves around inflammation and insufficient blood flow. but expect immunity to be the primary benefit you get from using the peptide.


BPC-157 (BPC = “body protecting compound) is a 15-amino-acid peptide produced in human gastric juice (i.e. stomach acid).

This peptide does not have a clear-cut mechanism of action, but we know for sure that new blood vessel formation is involved (albeit through a different pathway than TB-500), along with the release of the vasodilator nitric oxide.

Very similar to TB-500, BPC-157 has a reputation for accelerating the healing of numerous types of wounds and lowering inflammation.

But the research on its immune system effects is very sparse.

The most I could find was this one recently published paper arguing why BPC-157 should be considered a prophylactic treatment for COVID-19:

“BPC 157 is a peptide that has demonstrated anti-inflammatory, cytoprotective, and endothelial-protective effects in different organ systems in different species.

BPC 157 activated endothelial nitric oxide synthase (eNOS) is associated with nitric oxide (NO) release, tissue repair and angiomodulatory properties which can lead to improved vascular integrity and immune response, reduced proinflammatory profile, and reduced critical levels of the disease”

I would expect this peptide to to help the immune system in the same way TB-500 does.

BPC-157 has a very similar recommendation relative to TB-500, and I actually recommend using the two together as they work synergistically. BPC-157 is generally better for gut/intestine issues and TB-500 is better for heart/muscle issues. 

Thymosin Alpha-1

Thymosin Alpha-1 (TA1) is a peptide produced in your thymus gland that signals the secretion of T cells as part of the adaptive immune system response.

It also activates natural killer cells, lowers the production of pro-inflammatory cytokines, and helps normalize immune dysfunction.

TA1 is really effective against the flu (even in people who failed to get results from the flu shot), but the studies showing the peptide in its best light appear to be for specific diseases and not so much so for mechanisms.

The list of infectious diseases includes Hepatitis B & C, HIV-1, sepsis, chronic fatigue, and high-grade inflammation.

There was even one paper released at the very start of the COVID-19 pandemic where TA1 reduced mortality in patients with severe COVID-19, and then a few clinical trials that went nowhere.

But outside of this unfortunate news, it still has an underground reputation as an immune response modifier for viral infections.

TA1 should be your #1 choice if you can only pick one of the peptides out of this list and you need to treat an illness IMMEDIATELY, but it also plays nice in combination with the other four peptides. 

The “Kill Anything Virus-Related” Peptide Stack

Now that I’ve shown you all the peptides for immune system optimization one by one, here’s a fun example of how you would combine them together to fight off the nastiest viruses possible.

In early August 2022, my wife Monica and I returned from Mexico feeling incredibly ill.

Monica’s throat was on fire and I couldn’t stop sweating through my bed sheets at night.

Christopher Mercer from Limitless Life Nootropics then introduced me to a stack he uses for sinus infections that would pretty much kill anything, especially in fully optimized people.

  • TA-1: 2 mg taken 1-2x/day via subcutaneous injection
  • LL-37: 200 mcg taken 2 times a day via subcutaneous injection
  • VIP: 100 mcg daily via subcutaneous injection, or 2 nasal sprays administered 3x/day (Chris prefers the latter due to no flushing and equal outcome)
  • TB-500: 10 mg on the first day via subcutaneous injection and then 2.5 mg every following day until the infection is gone
  • BPC-157: 250 mcg taken 2x/day via subcutaneous injection to help with pain and inflammation

Frankly, it’s almost criminal that therapeutic peptides were not more aggressively pursued as the first line of defense early in the pandemic (SCAMdemic?).

Who knows how many lives we could have saved?

Summary: The Best Peptides For Immune System Enhancement

I think it’s fair to say this is as good as it gets for all the available peptides for immune system optimization.

You shouldn’t need to use them except in emergency situations when you come down with something really bad out of nowhere.

Otherwise, it’s better to live a fully optimized life that significantly lowers your chances of getting sick.

And have these peptides in your emergency toolbox for when you need them.

Whether you are brand new to the world of therapeutic peptides or hearing about them for the 1000th time, Limitless Life Nootropics continues to be the ONLY place I recommend for buying ultra-pure therapeutic peptides.

Use code JAY15 at the checkout cart for 15% off!

However, the newbies have some catching up to do before they can start injecting themselves silly.

Which is why I highly recommend you grab a copy of my Top 10 Mistakes People Make When Starting Therapeutic Peptides FREE PDF before you use peptides.


And make sure to read the emails I sent you after you get your PDF, otherwise you’ll miss the exclusive 50% OFF code for my Therapeutic Peptides Course.

As always…

Raise Your Vibration To Optimize Your Love Creation!

PS – For highly advanced tactics and strategies beyond peptides for being immune to diseases and pathogens, join The Fully Optimized Health Private Membership Group.

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