Life Extension Magazine®

Man in bed with the flu taking IgA for complications

An Innovative Approach to Stopping Colds and Flu

Scientists have identified a targeted probiotic cocktail that can boost the body’s immune defenses, in particular mucosal secretory IgA, thereby reducing colds, flu, and upper respiratory complications.

Scientifically reviewed by: Julia Dosik, MPH, in August 2023. Written by: Leslie Hunter.

The Centers for Disease Control and Prevention estimate that 56,000 people a year die from flu-related illnesses.1 During the 2015-2016 flu season 310,000 people were hospitalized due to flu-related illnesses.2

Colds and the flu are often treated with a variety of medications designed to reduce symptoms but that have no ability to activate the body’s own immune response to fend off invading bacteria or viruses.

Scientists wanted to find a way to stop the common cold and flu before they take hold.

Our bodies have a built-in security system called secretory IgA, which is present in mucosal membranes that line the nose and upper respiratory tract. IgA can prevent cold and flu viruses from entering.

With age, our ability to generate IgA secretions declines and this first line of defense is weakened.

Researchers started their investigations knowing that a critical aspect of the immune system is the microbiome in the gut, where a complex microenvironment of beneficial bacteria exist and interact.

Scientists discovered that a targeted probiotic cocktail of bacteria can boost the body’s immune defense system, in particular mucosal secretory IgA.

How IgA Protects Against Cold and Flu

How IgA Protects Against Cold and Flu  

Infections of the nose and upper respiratory tract pose a risk to older adults, who have a reduced immune response.3

This weakening of the immune system arises in part from reduced production of secretory antibodies that protect the nasal mucosa and respiratory tract mucosal surfaces from viral infection.

The decline of protective IgA helps explain why aging adults can be susceptible to infection by cold and flu viruses, as well as the Streptococcus pneumoniae bacterium, a cause of bacterial pneumonia in aging adults.4

To counteract this problem, researchers tested a unique oral probiotic blend designed to reduce the risk of respiratory infections by enhancing secretory immunity.

The term “secretory immunity” refers to production of specialized antibodies like IgA in the mucous membranes lining the nose, and portions of the windpipe and lungs.5

The importance of IgA antibodies is that they target both viral and bacterial invaders in the upper respiratory tract, deactivating them and presenting them for destruction by the immune system.6 This prevents both cold and flu viruses from gaining a foothold in the body. These pathogens are stopped before wreaking havoc in the body’s respiratory tract.

Blocking viral attachment to mucous membranes, in turn, prevents viruses from injecting their genetic material into human cells, and hence from replicating to produce more viruses.6

IgA is the acronym for immunoglobulin A. Increasing IgA secretion and breaking a viral replication cycle can prevent development of colds, influenza, and other respiratory infections.

What You Need to Know

Prevent Colds and the Flu With Oral Probiotics

  • Respiratory infections such as colds and the flu can be life-threatening for aging people.
  • A major source of this age-induced susceptibility is the gradual loss of secretory immunity, mediated by secretory antibodies called IgA.
  • IgA antibodies, secreted from mucous membranes in the mouth, nose, and lungs, bind to and block respiratory viruses from invading human cells and producing symptoms of colds and flu. But as their production fades, so does our immunity to these microbes.
  • Recent studies have revealed the surprising fact that selected strains of oral probiotic bacteria are capable of stimulating the intestinal immune system, resulting in body-wide increases in secretory immunity.
  • In the respiratory tree, this increase in IgA production leads to enhanced protection against cold and flu viruses.
  • Studies have now demonstrated convincingly that supplementing with these strains of probiotic bacteria results in significant reductions in the incidence and duration of year-round respiratory infections.
  • IgA is the acronym for immunoglobulin A.

Probiotics Slash Respiratory Infections

Researchers have identified several unique strains of targeted probiotics that have potent preventive effects on human respiratory infections. Their weapon against microbes, especially viruses that target the respiratory tract, appears to be the stimulation of IgA.

To see how this unique probiotic blend works to prevent infection by cold and flu, let’s look at a human clinical study. The trial was performed over the course of 90 days during cold and flu season with 250 subjects.7

The subjects were randomly assigned to receive either a placebo or a mixture of five unique probiotic strains specifically formulated to stimulate protective IgA:

  • L. plantarum (LP 01-LMG P-21021)
  • L. plantarum (LP 02-LMG P-21020)
  • L. rhamnosus (LR 04-DSM 16605)
  • L. rhamnosus (LR 05-DSM 19739)
  • B. lactis (BS 01-LMG P-21384)

During the course of the three-month study, subjects were asked to report all daily respiratory symptoms (runny nose, cough, fever, bronchitis, or pneumonia), along with the length and severity of symptoms.

All diseases accompanied by fever were classified as “flu-like syndromes,” while a separate category of “influenza-like illnesses” was also used. Other categories were “bronchitis-like” diseases, upper respiratory tract infections, common cold, and cough without other symptoms.

The study showed reduction in symptoms and reduction in the duration of symptoms.

The study findings showed:

  • 16 episodes of “influenza-like illnesses” in the placebo group compared to 3 such episodes in the probiotic cocktail group (a significant 81% reduction).
  • 31 episodes of colds among placebo recipients compared to 20 reported cases in the probiotic group. This 35% reduction did not quite achieve statistical significance.
  • Cold duration fell from 6 days in placebo recipients to 4.7 days in the probiotic supplemented patients, a 22% reduction.
  • Cough duration fell in the patients given the probiotic cocktail from 7.3 to 4.5 days, a 39% reduction.
  • Total acute upper respiratory infections fell from 6.1 to 4.6 days in the probiotic group, a 25% reduction.
  • A similar study showed a 48% reduction in flu episodes on subjects using the probiotic cocktail. The number of days with flu symptoms decreased significantly by 55%.8
Unleashing the Nuclear Bomb to Stop Colds and Flu

The importance of taking aggressive actions upon the first signs and symptoms of viral respiratory infections is critical. This protocol or “nuclear bomb” should be initiated within 24-48 hours of the manifestation of serious cold and flu symptoms.

  1. 800 mg of cimetidine (and higher). This drug is sold over the counter in pharmacies to combat heartburn, but its beneficial side effect is to boost immune function by reducing T-suppressor cells, thereby keeping the immune system active.15 Cimetidine can interact with prescription medications, so consult with a pharmacist and your physician before using. For most people, cimetidine provides immune system stimulation that is particularly effective against certain viruses.
  2. 9,000 mg of high-allicin garlic once or twice daily. This potent form of garlic will cause painful stomach-esophageal burning if you don’t eat food right afterward. Ingesting 9,000 mg of this kind of garlic will cause you to reek of a strong sulfur odor, but saturating the body with it is the objective. Garlic has shown direct virus-killing effects in a number of published studies.16,17
  3. 200 mg of DHEA early in the day. This is a high dose,18 but DHEA has shown some unique benefits in boosting one’s ability to mount a stronger immune response and also protecting against dangerous inflammatory cytokine responses that sometimes occur in response to viral infections.
  4. 1,200 mg a day of lactoferrin. This natural constituent of mother’s milk boosts natural killer-cell activity and can kill certain viruses.19
  5. One 18.5-mg zinc acetate lozenges every two waking hours. Please be aware that this is a very high dose of zinc and is considered toxic if taken over the long term.20,21 You should only do this for a few days. Zinc has shown a direct effect of inhibiting cold viruses from latching onto your cells.19
  6. 10-50 mg of melatonin at bedtime (ordinarily, melatonin is taken at levels of just 1–3 mg per evening). Melatonin induces a powerful immune response and this high dose can facilitate the deep sleep one often needs to fend off an infection. This dose of melatonin will make you extremely tired, so please only take this before bedtime and do not operate any machinery or vehicles after ingestion.22
  7. 3,600 mg a day of aged garlic extract. There are unique immune-boosting compounds in aged garlic that work differently than those found in high-allicin garlic.23
  8. As discussed on the sidebar on page 45, the prescription drug Tamiflu® in the dose of 75 mg twice a day should be started within 24 hours of flu symptoms manifesting to block entry of certain viruses into cells where they multiply.

Do not delay in implementing the above regimen. Once a flu virus infects too many cells, it replicates out of control and strategies like zinc lozenges will not be effective. Treatment should be initiated as soon as possible after symptoms manifest!

Adding Bacillus Subtilis CU1 to the Probiotic Cocktail

In another study, scientists identified a sixth probiotic that also provided immune-stimulating features among aging adults at risk for respiratory infections.9

This bacteria, Bacillus subtilis CU1, creates a natural protective shield that resists the acid in the stomach, promoting the probiotics’ survival into the digestive tract.10 Previous studies have shown that this strain of probiotic can stimulate IgA in humans, a mechanism of great interest in preventing respiratory infections.9,11

A human clinical trial was conducted among healthy older adults (ages 60-74) who were randomly assigned to receive this probiotic or a placebo.9 Subjects took one capsule daily, containing two billion microorganisms per capsule.

Supplemented subjects experienced a significant 45% drop in the frequency of respiratory infections. Notably, a concomitant significant 45% increase in concentrations of IgA was demonstrated in their saliva, strongly suggesting that increased IgA was at least in part responsible for the observed impact. No significant side effects were noted in either group.

The Importance of Dendritic Cells

How can ingestion of a probiotic lead to increased secretion of IgA in the nose and throat?

IgA production can be stimulated or reduced throughout the body, depending on the environment sensed by specialized cells called dendritic cells. Dendritic cells can detect molecular patterns on the surfaces of the billions of bacteria and viruses we swallow every day, whether they enter our bodies through the mouth or the nose.7

Once dendritic cells have encountered these microbial identifiers, they “teach” other immune system cells about the nature of the threat, prompting them to pump out IgA, among other defensive molecules.7

IgA is secreted throughout the body, including mucous membranes of the mouth and nose.12 Increased IgA in those areas results in increased protection against invaders attempting to enter the body through those membranes.7

Studies have demonstrated that orally-ingested probiotics stimulate IgA in the mucous membranes of the bronchi (larger air tubes in the lungs).7,12 Similarly, probiotics have been shown to reduce the incidence and severity of respiratory infections in children.7,13

Thus, orally ingested probiotics appear capable of sealing the age-induced gap in secretory immunity that puts so many older adults at grave risk for respiratory infections every year.

The discovery of the unique IgA-stimulating properties of oral probiotics opens a new world in modulation and strengthening of our aging immune systems, and provides a new weapon in our battle against respiratory illness.

When Influenza Turns Deadly: Life-threatening Influenza Requiring Hospitalization
When Influenza Turns Deadly

Those over the age of 65 as well as aging individuals with chronic diseases that may weaken the immune system, cardiovascular system, and/or respiratory tract (e.g. diabetes, cardiovascular, and chronic lung disease) are at higher risk of developing potentially life-threatening infections including the dreaded influenza pneumonia that is linked to a high mortality rate.

In contrast to younger and generally healthy patients, these high-risk patients may not necessarily manifest a high fever initially (a body temperature in excess of 102.5 degrees Fahrenheit) since impaired thermoregulation is observed with aging.

Headache, dramatic fatigue, muscle aches, a nonproductive cough (initially), and nasal congestion are important signs and symptoms of influenza infection in older patients. Additional signs and symptoms in older patients may include cognitive dysfunction and confusion, difficulty walking, and falls.

Worrisome signs and symptoms for patients with influenza infection suggesting pneumonia include:

  • Respiratory rate above 25 breaths per minute, reflecting difficulty with oxygenation
  • Hypotension (blood pressure below 90/60 mm Hg),
  • Bloody sputum

Labs tests that also suggest severe disease include:

  • Elevated lactate dehydrogenase (LDH)
  • Elevated creatine phosphokinase (CPK)
  • Hypoxemia (the inability to oxygenate the blood) increases rapidly to the point of respiratory failure in many of these patients requiring mechanical ventilation, often after only 24 to 48 hours.

The most important pharmacologic intervention to reduce the risk of death in these patients, in addition to cardiovascular and respiratory supportive measures, is rapid identification of viral strain, and rapid antiviral treatment with neuraminidase inhibitors, e.g., oseltamivir (Tamiflu®) and zanamivir (Relenza®), initiated as soon as possible, ideally within 24 hours.


cold or flu  

A cold or flu can pose serious risks for aging adults. Such infections can lead to potentially fatal bacterial infections, particularly pneumonia, which kills more than 50,000 Americans annually.14

One main source of the age-related increase of viral respiratory infections is the loss of secretory immunity, which is controlled by a class of antibodies known as IgA.

As aging adults lose IgA protection, they lose their ability to defend against viruses attacking the mucous membranes in the nose, lungs, and bronchi of the respiratory tract.

Specific strains of probiotic bacteria, ingested orally, have the ability to stimulate IgA production in the respiratory mucous membranes, thereby preventing attachment by, and infection with, common viruses.

Human studies demonstrate that supplementation with the proper blend of probiotic strains reduces the incidence of colds and flu-like illnesses, an effect largely attributable to increases in levels of IgA.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.


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