Mucosa, host defense, and the role of stress
Our immunity is a sophisticated, subtle learning system that works best when it is fully engaged. So we strive to support our immune system’s own functional processes, much like we would support the innate curiosity and exploring mind of a child. There is a long tradition in herbal medicine of using herbs and mushrooms around times of seasonal change, or during travel, to support great immunity and thereby keep the physiology strong and resilient. The strategy focuses on three main areas: first, herbalists value the health and integrity of the mucosa (our barrier from the outside world, and first line of defense). Second, we work to both support and balance host immunity (the activity of our white blood cells, complement proteins, and inflammatory molecules that interact with the world both inside and outside our bodies). Third, we try to remain mindful of the stress in our lives, cognizant that
A LITTLE STRESS IS IMPORTANT TO DRIVE PASSION AND ENGAGEMENT, BUT THAT TOO MUCH (EITHER PHYSICAL OR MENTAL/EMOTIONAL) STRESS CAN BEGIN TO DEPRESS IMMUNITY.1
There are two pieces to mucosal immunity: the integrity of the barriers that line our respiratory and digestive passages, and the lymph tissue, rich in white blood cells, found all throughout the gut (and, to a certain extent, the respiratory system). To support good mucosal integrity, herbalists turn to plants that support normal, healthy tone in the membranes, and also ones that are soothing and moisturizing to our tissues when applied topically. Ginger is a great example of a warming herb that supports a healthy inflammatory response, especially during stressful times like after endurance exercise.2 Roots like licorice or marshmallow are some of our most soothing, protective agents to support healthy mucosal tone.3 Taken together, they are both energetically balanced--a great combination of warming and cooling, dry and moist--and supportive to the integrity of our protective barriers. And speaking of balance, one of our favorite herbs for optimal mucosal tone is Schisandra--a five-flavored berry that is sweet and sour, soothing and toning, and while it possesses many virtues, can also be used for a balanced immune response in the mucosa.4
When taking herbs by mouth as teas or tinctures, one might wonder if their active chemistry is able to join in the conversation with our immune system. After all, compounds such as high-molecular-weight polysaccharides (glucans, for example) or saponins have low oral bio-availability, meaning it’s challenging to get them into the bloodstream.5 But getting into the blood may not be necessary: part of the beauty of our digestive mucosa is that it is studded with patches of lymph tissue rich in immune cells. This makes sense: our immune system is attempting to sample and understand the contents of our bellies, and making decisions about function and support in response to what it discovers. Botanical and fungal compounds can interface with white blood cells right inside our GI tract, without the need to be absorbed into the bloodstream.6
Great news for us: sipping bone broth with herbs, drinking teas, or taking tinctures turn out to be great ways to support a healthy immune response.
We can add roots like Astragalus or Codonopsis,7rich in saponins and polysaccharides, or mushrooms like reishi, shiitake, maitake, turkey tail, and more into our daily regimes confident that, when taken by mouth, their chemistry interfaces directly with our mucosal immunity, talking to it in its own language. In fact, there is a good body of evidence showing that constituents such as botanical saponins are so good at supporting an optimal immune response that they are called “immune-stimulating complexes (ISCOMs)”. In some cases, they are even added to vaccines to promote a better immune response.8
This leads directly to the role herbs and mushrooms play in modulating host immunity. If these botanical and fungal constituents can exploit mucosal immunity to speak to the white blood cells found there, we should expect an ability to interact with overall host immunity. “Host” immunity is defined as the coordinated response, executed by cellular, hormonal, and peptide players, that each one of us (the “host”) can call upon to maintain a stable internal cellular environment. We are, of course, hosts to our own cells and to a lot of other cells, too: the microbes in our GI tracts, on our skin, in our respiratory systems, and more. Truly, as first penned by Whitman (and most recently paraphrased by Ed Yong),9 we contain multitudes. The trick is balancing the host’s cells, friendly bacteria, and potential pathogens: this is where the subtle complexity and wisdom of our immune system becomes apparent. How does host immunity distinguish between self and other, friend and foe?
Our host defenses are usually subdivided into two categories: the innate response, which is quick, ready, and dominated by proteins and cells capable of killing or engulfing harmful microbes; and the acquired response, which is slower, helps us remember, train, and modulate the overall immune response, and is dominated by antibodies and lymphocytes such as T and B cells. Many medicinal polysaccharides, as we’ve seen, have an effect on innate immunity and support the optimal activity of those cells and proteins.10 But perhaps more importantly,
roots such as Astragalus11 and mushrooms such as reishi12 and maitake13 are able to modulate, or balance, the acquired response:
by interfacing with the cells at work here, immune-active herbs and mushrooms can extend their influence across the whole host response. The acquired response is what helps the immune system discriminate and navigate the multitudes inside and outside of us--so a well-balanced response is essential.
The final consideration in herbalists’ minds as we approach the colder months is the level of stress in our lives, and how this might affect our immune response.
WE’VE KNOWN FOR SOME TIME THAT THE CLASS OF HERBAL TONICS KNOWN AS “ADAPTOGENS” (HERBS LIKE GINSENG, ELEUTHERO, SCHISANDRA, RHODIOLA, CORDYCEPS, REISHI AND TULSI TO NAME A FEW) CAN HELP THE BODY WITHSTAND THE CHALLENGES OF OCCASIONAL STRESS MORE EFFECTIVELY.14
Given the connections between stress and decreased immune function, one might expect that adaptogens could have an impact on immunity, too. This does seem to be the case: herbs like ginseng have a long history of use to support immunity,15 and others like eleuthero are showing themselves to be valuable adjuncts as well.16 Of course we’ve already seen that mushrooms like reishi can play important immune-supportive roles. This brings up a couple of interesting points: first off, the chemistry of adaptogens like ginseng and eleuthero, rich in saponins and in some cases immune-active polysaccharides, closely approximates that of our immune-active tonics--so it stands to reason there would be some functional crossover as well. But second, there may be more of a connection between our moods, stress, and immunity than we realize: the dance between our host defense and the multitudes we contain may impact our personality, consciousness, and stress response.17 So herbalists often think of adaptogens as overall stress-, immune-, and mood-balancing herbs. We include them in almost every preparation designed to make human beings more resilient--and immune resilience is no exception.
In sum, with a little attention paid to our mucous membranes, a little support for stress in the form of herbal adaptogens, and an immunomodulating “conversation” between our host immunity and medicinal herbs and mushrooms, we can go a long way towards ensuring a healthy, balanced response. The botanicals and fungi used most often taste great--or at least, fairly neutral in flavor--making them easy additions to broths, sauces, soups, teas and tincture blends. Just remember that a little more heat might be required for the tougher roots and fruiting bodies: often ten minutes of simmering does the trick, but in some recipes, mushrooms are put into a crock pot for eight or even 24 hours. This can make pre-extracted products like tinctures a convenient choice. But any way you choose it, think about the herbalist’s approach to healthy immunity any time the seasons change, you’re traveling, expect to come into a high-exposure situation, or want to ensure full immunity after an illness has passed. Long-term use of these remedies works best: remember that you’re interacting with a sophisticated, learning system, for which change takes time. But after a few weeks of connection, you will see the results: challenged, engaged, and enlivened by its newfound dance with botanical biodiversity, your immune system will be your foundation for wellness.
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2. Zehsaz, Farzad, Negin Farhangi, and Lamia Mirheidari. “Clinical immunology The effect of Zingiber officinale R. rhizomes (ginger) on plasma pro-inflammatory cytokine levels in well-trained male endurance runners.” Central European Journal of Immunology39.2 (2014): 174-180.
3. Burgess, J. A., et al. “Review of over-the-counter treatments for aphthous ulceration and results from use of a dissolving oral patch containing glycyrrhiza complex herbal extract.” J Contemp Dent Pract9.3 (2008): 88-98
Asl, Marjan Nassiri, and Hossein Hosseinzadeh. “Review of pharmacological effects of Glycyrrhiza sp. and its bioactive compounds.” Phytotherapy research 22.6 (2008): 709-724.
4. HE, Xiao-yu, Jie LUO, and Ying-lun LI. “Effects of fermented dregs of Schisandra chinensis on intestinal morphology and mucosal immunity of weaned piglets.” Journal of Hunan Agricultural University (Natural Sciences)2 (2014): 018.
LIU, Miao, et al. “Anti-type-I hypersensitivity of Schisandra chinensis polysaccharide.” Chinese Traditional Patent Medicine 4 (2012): 013.
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6. Novak, M., and V. Vetvicka. “Glucans as biological response modifiers.” Endocrine, Metabolic & Immune Disorders-Drug Targets (Formerly Current Drug Targets-Immune, Endocrine & Metabolic Disorders)9.1 (2009): 67-75.
7. Yongxu, Sun, and Liu Jicheng. “Structural characterization of a water-soluble polysaccharide from the roots of Codonopsis pilosula and its immunity activity.” International Journal of Biological Macromolecules43.3 (2008): 279-282.
8. Cox JC et al (1998). “ISCOMs and other saponin-based adjuvants.” Adv Drug Deliv Rev 32 (3).
9. Yong, Ed. I contain multitudes: The microbes within us and a grander view of life. Random House, 2016.
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Kuo, Mei-Chun, et al. “Ganoderma lucidum mycelia enhance innate immunity by activating NF-κB.” Journal of ethnopharmacology 103.2 (2006): 217-222.
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Mao, S. P., K. L. Cheng, and Y. F. Zhou. “Modulatory effect of Astragalus membranaceus on Th1/Th2 cytokine in patients with herpes simplex keratitis.” Chinese journal of integrated traditional and Western medicine 24.2 (2004): 121-123
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14. Panossian, Alexander, and Georg Wikman. “Evidence-based efficacy of adaptogens in fatigue, and molecular mechanisms related to their stress-protective activity.” Current clinical pharmacology4.3 (2009): 198-219.
15. Kang, Soowon, and Hyeyoung Min. “Ginseng, the ‘immunity boost’: the effects of Panax ginseng on immune system.” Journal of ginseng research36.4 (2012): 354.
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17. Dinan, Timothy G., and John F. Cryan. “Microbes, immunity, and behavior: psychoneuroimmunology meets the microbiome.” Neuropsychopharmacology(2016).
(Updated, October 2018)