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A sticky situation: mucus support for respiratory illnesses.

Mucus is our friend. It coats the conducting pathways of the respiratory system, protecting the body from invading bugs. It forms a complete barrier between the outside world and the inside world of the body, and its production can be triggered by irritants, infection, pollution, and cigarette smoke. As a naturopathic physician, when I treat respiratory disease, I am thinking about treating a patient's mucus. Is he or she making enough? Is it too thick? Can it do its job? In this article we will investigate the properties of mucus, its function, and naturopathic ways to manipulate it.

Mucus secretions increase in asthma, bronchitis, emphysema, cystic fibrosis, sinusitis, and cold/flu. In any one of these conditions, mucus is thicker, denser, and harder to clear than normal. A common strategy in any lung pathology is to thin a patient's mucus and create more so that the body can more easily remove it.

As a naturopath, I never want to dry up someone's mucus (there are drugs that have this property), as it is a natural protecting agent in the body. I want to facilitate the body in making a mucus that's extremely easy to move through the respiratory tract--essentially mucus that's very thin and watery. A thin and watery mucus is more easily moved against gravity with the beating of cilia, small hairlike projections from cells that line the respiratory tract.

What's in Mucus?

Made by cells that line the respiratory tract, mucus is composed mainly of water and glycoproteins called mucins. Other ingredients include lysozymes, immunoglobulins, lactoferrin, and salts.

Lysozymes: Lysozymes are enzymes (glycoside hydrolases) that break up bacterial cell walls. Lysozymes are abundant in saliva, human milk, tears, mucus, and the granules inside neutrophils. They are particularly effective against gram-positive bacteria such as Streptococcus. Egg whites contain high levels of lysozymes, and this fact forms the basis for the home treatment of egg white masks on the face for acne.

Immunoglobulins: Immunoglobulin IgA predominates in mucus. IgA is produced in the tissue space by plasma cells and then transported across the plasma membrane to the outside of the body. It is found in saliva, tears, human milk, and mucus. A genetic immunodeficiency of secretory IgA will predispose the patient to more frequent infections. In individuals with this condition, the genetic abnormality is not treated; instead, the physician prescribes a proactive regime to prevent common mucosal infections (sinusitis, urinary tract infections, and cold/flu).

Lactoferrin: Lactoferrin, a glycoprotein, is also found in various secretory fluids, including mucus. Lactoferrin is most concentrated, however, in human colostrum, followed by human milk, and then in cow's milk. Lactoferrin has anticancer, antiparasitic, antibacterial, antiviral, and antiallergic properties.' Lactoferrin binds to bacteria, and the iron component of the molecule oxidizes the bacteria's cell walls, causing their breakdown. (2)

Mucins: Mucins are a group of glycosolated protein (sugar plus protein) molecules that are unique in their ability to form gels. These gels form a physical barrier protecting airways from particles and pathogens and give mucus its sticky quality.

In the respiratory system, mucus is produced all along the conducting system. Its function is to trap particulate (dust, allergens, pollutants) and pathogens (fungi, bacteria, viruses), and move them through the beating of cilia. Cilia move the mucus toward the oropharynx to be swallowed. Once swallowed, these molecules are degraded and eliminated through the gastrointestinal tract.

Substances that Affect Mucus

Drugs and natural substances that act on mucus can be classified by their mechanism of action:

* Expectorants work by increasing the total amount of mucus made. This increase results in thinner, clearer mucus that can more easily be moved up and out the respiratory tract. They also work by increasing ciliary beating speed, thus improving the clearing time of mucus.

* Mucolytic agents work by dissolving the chemical bonds in mucus, thus lowering its viscosity.


Many herbs have expectorant properties, and most herbal medicines do triple duty: easing cough, increasing mucous production or movement, and acting as an anti-inflammatory at the same time. Although the traditional use of herbs as expectorants is vast, there is scant scientific evidence.

These herbs have a long history of expectorant use:

* Glycerrhiza glabra (licorice)

* Commiphora molmol (myrrh)

* Grindelia cam porum (grindelia)

* Thymus mongolicus (thyme)

* Inula helenium (elecampane)

* Marrubium vulgare (white horehound)

* Hysso pus officinalis (hyssop)

* Eriodictyon augustifilium (yerba sante)

* Prunus serotina (wild cherry)

These herbs can be given in capsules, as teas, or as extracts.

Three more herbs that increase ciliary transport of mucus are Tussilago farfara (coltsfoot), Fructus foeniculi (fennel), and Fructus anisi (anise) (3) Coltsfoot is a common respiratory herb. It is widely used for the treatment of cough, bronchitis, and asthmatic disorders. In vivo, the flower bud (the active component of the plant) lengthened the latent period of cough, decreased cough frequency, and enhanced tracheal mucus secretions. (5)

Elaeagnus pungens is a Chinese herb in the Oleaster family with the common name thorny olive or silverthorn. It is a common plant used in landscaping and ornamental gardening, such as in bonsai. In a 2009 study, researchers found that it has expectorant properties. The leaf was also found to have antitussive (anticough) properties, delaying cough, and reducing cough frequency. (4)

In a 2003 study, researchers looked at several herbs that increase mucin production from mucin-producing cells. Specifically, they tested the plant constituents berberine, curcumin, and hesperidin from Coptis japonica, Curcuma longa, and Poncirus trifoliata, respectively. They state: "We conclude that berberine, curcumin and hesperidin can increase mucin release by directly acting on airway mucin-secreting cells and suggest that these agents be further studied for possible use as mild expectorants during the treatment of chronic airway diseases." (6)

Mucolytic Agents

A Mucus-Friendly Drug: Guaifenesin is one of my favorite treatments for improving the quality of a patient's mucus. As a naturopathic doctor, I find very few drugs that I like--but guaifenesin is one of them. Guaifenesin, approved in 1952 by the FDA, has very few side effects (and none of them major). It is extremely effective at increasing the volume and reducing the viscosity of mucus secretions. Essentially, it is a drug with a naturopathic mechanism: supporting the body to clean and clear thick mucus up and out of the lungs or sinuses.

It is also used to increase fertile cervical mucus and there is some research showing that it helps with fibromyalgia symptoms.

I recommend that guaifenesin be taken in sustained-release formulas (I like 1200 mg two to three times per day), with ample water in order to form that more slippery, abundant mucus.

A Mucolytic Amino Acid: N-acetylcysteine (NAC) is a sulfur-containing amino acid sold as a pharmaceutical drug as well as an over-the-counter supplement. This amino acid is involved in the sulfation cycle and in phase II liver detoxification, and acts as a methyl donor in the conversion of homocysteine to methionine. Cysteine aids in making glutathione, one of the body's most powerful antioxidants. Because of its strong help in liver detoxification, it is used allopathically to treat acute acetaminophen poisoning in a hospital setting.

NAC will break disulfide bonds, creating two sulfhydryl molecules. This action results in the breakdown of mucoproteins in the respiratory system, as it clears thick mucus up so that it can be more easily transported up and out of the body.

In a study that followed moderate to severe COPD (chronic obstructive pulmonary disease) patients, NAC plus conventional treatment improved multiple parameters better than conventional treatment alone. The results showed a decreased number of exacerbations (by 41%) in the group of patients treated with NAC and standard treatment: 46 patients had at least one exacerbation as compared with 63 patients of the group treated with standard therapy alone. Also the number of the patients with two or more exacerbations was lower in the NAC group (26%) than in the standard-therapy group (49%). The number of sick days was less (82) in the NAC group as compared with the standard-therapy group (155). (7)

In a review of the effects of NAC in chronic bronchitis, oral NAC reduced the risk of exacerbations and reduced symptoms in patients with bronchitis compared with those who took only placebo, without any side effects. (8) In addition to the mucolytic properties of NAC, this antioxidant has also been shown to inhibit replication of human influenza viruses and decreases the production of pro-inflammatory molecules in virus-infected cells. (9)

A Mucolytic Element: Potassium iodide (P1) is used traditionally as a mucolytic, because of its ability to break up disulfide bonds. It has also been found to stimulate the cilia in the respiratory tract. Potassium iodide increases ciliary beat frequency. (10) Because it also has antimicrobial properties, this is a great treatment to add in with patients who have respiratory infections.

Diet and Mucus Production

Anecdotally, naturopathic physicians find that dairy products increase some patients' overall mucus production. These patients may avoid dairy all the time or just during times of respiratory infection. There is a body of evidence on PubMed that shows no increase in mucus production from dairy consumption.

One study does, however, link the two. Researchers have isolated beta-casomorphin-7, an opioid protein found in milk, and found it to increase mucin (a major protein in mucus) production. Increased mucin production occurred through a nervous pathway via opioid receptor activation. This finding may explain why allergic models have failed to support the milk/mucus connection. (11)

Another major consideration to address with patients is dehydration. A dehydrated body will shunt water from mucous production and keep it in the bloodstream, where it is needed more acutely. This will give the patient a very dry, thick, and sticky mucus, which can't be cleared easily. I remind my patients that plain water added to a bloodstream with already low levels of electrolytes will be eliminated through the kidneys, and ask them to add a small amount of electrolyte solution to all the water that they consume. Remember that electrolytes are natural constituents of mucus.


When designing a protocol for a patient with a respiratory illness, COPD, cold/flu, or sinusitis, I always consider adding in therapies to increase, thin, and mobilize mucus. Mucus helps the body protect itself as well as clean up debris from infectious agents, pollution, and other particulate matter in the air. Its production should be supported, not eliminated, for optimal healing. Oftentimes a protocol for a respiratory illness will look something like this:

* elimination of dairy, wheat, sugar, and alcohol;

* increase in water consumption and adding electrolytes to almost all water consumed

* an herbal formula as a capsule, tea, or tincture that has expectorant and antimicrobial properties

* guaifenesin 1200 mg twice daily

* N-acetylcysteine 900 mg twice daily

* lodoral 12.5 mg one tablet daily

Patients should trust that the body innately knows how to clear an infection in the respiratory tract. If they support their bodies in this, their immune systems will become stronger and they will suffer from fewer infections overall. Supporting the body's natural mucus production and clearance is one powerful way in doing so.

RELATED ARTICLE: For Cold and Flu, Innate immunity Is the Key

With the winter season rapidly approaching, influenza virus infection and related sequelae are significant concerns to public health. With the success of the yearly flu vaccine being unpredictable at best, agents that modify the host response to infection have become increasingly attractive. One such agent, a hybridized mushroom extract called active hexose correlated compound (AHCC), has been reported to increase survival, decrease the severity of infection, and shorten recovery time in an established experimental model of influenza virus infection (J Nutr. 2006;136; Nutr Rev. 2008;66; Nutr Res. 2009;29).

To summarize this research, AHCC increased the number and activity of natural killer (NK) cells, thought by many immunologists to be the frontline defense of the immune system. As we know, NK cells are part of the innate immune system, or innate immunity. When functioning well, innate immunity can deal effectively and quickly with health threats that the body has not previously experienced, such as a new virus or type of bacterial infection.

In these studies, AHCC increased NK cell activity enough to actually allow clearance of the inflammation, but did not require the assistance of adaptive or humoral immunity, which can overreact to the point of detriment. This is extremely important because the adaptive immune system cells, while beneficial in many ways, can also cause inflammation that damages lung tissue and increases severity of flu symptoms.

A boost of innate immunity, especially NK cell activity, can substantially decrease the severity of colds and influenza, help speed recovery, and result in less "collateral damage" to the lung.


(1.) Adlerova L, Bartoskova A, Faldyna M. Lactoferrin: a review. Veternarni Medicina. 2008;53(9):457.

(2.) Farnaud S, Evans RW. Lactoferrin--a multifunctional protein with antimicrobial properties. Mol Immunol. 2003;40(7):395-405.

(3.) Muller-Limmroth W, Frohlich HH. Effect of various phytotherapeutic expectorants on in transport. Fortschr Med. 1980 Jan 24;98(3):95-101.

(4.) Ge Y, Liu J, Su D. In vivo evaluation of the antiasthmatic, antitussive and expectorant activities of extract and fractions from Elaeagnus pungens leaf. J Ethnopharmacol. 2009 Dec 10; 126(3):538542. Epub 2009 Sep 6.

(5.) Li ZY et al. Metabolic profiling of the flower bud and rachis of Tussilago farfara with antitussive and expectorant effects on mice. J Ethnopharmacol. 2012 Mar 6;140(1):83-90. Epub 2011 Dec 24.

(6.) Lee CJ et al. Effects of baicalein, berberine, curcumin, and hesperidin on mucin release from airway goblet cells. Planta Med. 2003 Jun; 69(6):523-526.

(7.) Pela R, Calcagni AM, Subiaco S, Isidori P, Tubaldi A, Sanguinetti CM. N-acetylcysteine reduces the exacerbation rate in patients with moderate to severe COPD. Respiration. 1999;66(6):495-500.

(8.) Stey C. The effect of oral N-acetylcysteine in chronic bronchitis: a quantitative systemic review. Eur Respir J. 2000 Aug. 16(2):253-262.

(9.) Geiler J et al. N-acetyl-L-cysteine (NAC) inhibits virus replication and expression of pro-inflammatory molecules in A549 cells infected with highly pathogenic H5N1 influenza A virus. Biochem Pharmacol. 2010 Feb 1;79(3):413-420.

(10). Melville GN et al. Tracheobronchial function in health and disease. Effect of mucolytic substances. Respiration. 1980;40(6):329-336.

(11). Zoghbi S et al. Beta-casomorphin-7 regulates the secretion and expression of gastrointestinal mucins through a mu-opioid pathway. Am J Physiol Gastrointest Liver Physiol. 2006 Jun; 290(6):G1105-G1113.

by Amy Terlisner, NMD


Dr. Amy Terlisner attended the University of Georgia in Athens, Georgia, where she obtained a BS in holistic medicine, a degree that she customized for her later studies in naturopathic medicine. She graduated summa cum laude (with highest honor) and published an undergraduate thesis in health psychology. Dr. Terlisner then attended Bastyr University in Seattle, Washington. She has an extensive teaching background and has taught physiology, anatomy, clinical laboratory diagnosis, pharmacognosy, physical exam diagnosis, and manipulation at the doctorate level. Her specialties include women's health, cardiovascular disease, gastroenterology, anti-aging medicine, and natural hormone replacement therapy. Dr. Terlisner is the current president of the Arizona Association of Naturopathic Physicians and owns ALETRIS Center of Integrative Medicine, located in Scottsdale, Arizona.
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Title Annotation:Mucus Support
Author:Terlisner, Amy
Publication:Townsend Letter
Article Type:Report
Geographic Code:1USA
Date:Dec 1, 2012
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