Are you (or the people around you) “coming down with something” — a respiratory bug you’d rather not have? Some of the most convenient and economical sources of immune support can be found right in your pantry, in the form of immune-boosting foods, herbs, and spices. Some of our favorites are those that act on the respiratory tract as well as the immune system, to be used either before you experience symptoms or when you first notice that tickle in your throat or nose. Including foods that act as natural anti-inflammatories in your diet can also benefit the immune and respiratory systems.

Tea. Many types of tea have long been revered for their health-enhancing effects, and much research has focused on its antioxidant effects. But along with its antioxidant effects, drinkers of true tea (Camellia sinensis) — black, green, white, or oolong — are enjoying a range of phytochemicals that can help them avoid infection. One tea ingredient, L-theanine, appears to prime the memory of core T cells in the immune system, teaching them to recognize certain molecular subcomponents of invading bacterial, parasitic, and viral microbes when encountered for the first time, so they can mount a significantly stronger response than “naïve” T cells.

5 Medicinal herbs for cold and flu season

For generations certain herbs were identified as preventives for colds and flu, widely used in various forms and combinations, and regarded as invaluable for warding off infection and decreasing severity and duration of symptoms.

Modern science has placed these medicinal herbs under intense scrutiny, and the research on some has been mixed yet supportive. We now have a growing body of evidence confirming overall lower incidence of flu and cold infection with the use of certain herbs, while other studies demonstrate intriguing immune-stimulating activity. Herbal medicines are thought to neutralize or limit the success of seasonal viruses in myriad ways, but principally by increasing immune cell numbers and function, gene expression, and cell-signaling activity in the body. Others appear to act upon the virus particles themselves.

Most botanical preparations containing these herbs work best when taken as preventives, or as soon as symptoms become evident. Here are 5 for which the science is strong.

1) Astragalus (A. membranaceous)*
2) Black elderberry (Sambucus nigra)
3) Cordyceps (C. militaris)*
4) Echinacea (E. angustifolia, E. purpurea, E. pallida)
5) Eleuthero (Siberian ginseng — Eleutherococcus senticosus)*

* Herbs included in Women's Health Network’s Adaptisol formulation.


Another group of compounds in tea called catechins are under evaluation for their antimicrobial effects. Green tea extracts rich in epigallocatechin gallate (EGCG), the major polyphenol in tea, have been shown to have antiviral effects against influenza A virus (seasonal flu) in the laboratory, and EGCG and its relatives are considered to be the likely source of this effect. In another recent study on mice, EGCG demonstrated strong effects against the H1N1 virus in particular. The exterior surfaces of influenza viruses are covered with protein-dense knobs responsible for binding to the cells being infected. Studies on EGCG suggest one way it inhibits the virus’s infectivity is by binding to these knobs so as to “preoccupy” them, actually altering the physical properties of the viral membrane.

And staying well-hydrated by drinking tea infusions also helps keep your sinuses, throat, and nasal passages from becoming clogged up — just take care to ensure the caffeine in these teas doesn’t prevent you from getting the sleep you need.

Herbal tisanes. When steeped in boiling water, just about any herb or plant material that is not tea leaves becomes what is known traditionally as a tisane. If left to brew for some time, it becomes an infusion. Whether brewed as single ingredients or in combination, there are countless varieties of these herbal tisanes and infusions, with an equally diverse range of health-enhancing applications. As observed for centuries, studies on herbs are now elucidating the molecular mechanisms underlying these longstanding observations, and we now have a better, albeit still limited understanding of how they enhance our overall well-being.

But you need not brew up a tisane to derive better immunity, as herbs can be compounded in a wide range of forms, including tinctures, extracts, homeopathic and combination preparations. One of the best known and most widely used herbs, Echinacea, has been long considered a source of immune support in traditional medicine but regarded with mixed feelings by conventional practitioners. Laboratory studies on different Echinacea species, plant parts, and preparations have demonstrated a variety of antiviral properties, useful in preventing and fending off respiratory viruses.

These studies also demonstrate, however, that Echinacea preparations can differ greatly, as can their effectiveness. We recommend you look for organically grown or sustainably harvested herbs, and if using supplements, choose high-quality standardized extracts, whether Echinacea or other medicinal herbs. (See above table of 5 herbs for cold and flu season for our favorites.) For ongoing or more serious immunological or inflammatory concerns, please consult with a qualified professional for the best overall outcome.

Garlic. Used for millennia to combat respiratory and other infections, including viral illnesses, garlic contains a number of compounds, such as ajoene and allicin, that show potent antibacterial and virucidal activity. Scientific data on its proposed antiviral properties are still somewhat limited, but studies have shown that garlic promotes overall immune health, that it is active against specific bacterial infections of the respiratory tract, and that it may bolster the ability of the respiratory tract to defend against viral infection.

Hot peppers. Chili peppers such as jalapeño, poblano, or serrano contain moderate levels of the compound capsaicin, which is what makes peppers burn in your mouth — and clear out your sinuses! Adding these peppers to soups and other dishes can help open up clogged airways and promote better drainage of the sinuses, which in turn helps rid them of infectious bacteria, viruses, and the mucus and cellular debris associated with them. Peppers are also a high-quality source of vitamin C. As with some other natural treatments, the research on vitamin C and cold and flu prevention has been mixed and somewhat controversial. That said, vitamin C (ascorbic acid) is a powerful antioxidant, and it does appear to benefit the immune response, reduce the duration of respiratory symptoms, and may have some direct effects against influenza.

Chicken soup. Mothers and grandmothers have prescribed homemade chicken soup as a remedy for colds and flu for generations — perhaps since ancient Greece — and with good reason! It may not be a cure-all, but chicken soup does have a number of benefits for overall immune health and a healthy respiratory tract, and it certainly is comforting. As part of the natural inflammatory response, respiratory viruses like the common cold and influenza cause immune cells called neutrophils to migrate to the mucosal lining of the airways — this is thought to be what causes the secretion of mucus. Chicken soup has been shown to significantly limit the number of neutrophils that get drawn in. Steam from chicken soup helps open nasal passages, so it also helps remove infectious particles from your airways in that fashion. (And if you make a chicken soup with fresh, homemade broth, garlic, and a jalapeño pepper, you’ll have a triple whammy for your respiratory health!)


1 Rowe, C., et al. 2007. Specific formulation of Camellia sinensis prevents cold and flu symptoms and enhances [gamma delta] T-cell function: A randomized, double-blind, placebo-controlled study. J. Am. Coll. Nutr., 26 (5), 445–452. URL: (accessed 10.14.2009).

  Kamath, A., et al. 2003. Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses. Proc. Natl. Acad. Sci. USA, 100 (10), 6009–6014. URL: (accessed 09.29.2009).

  Bukowski, J., et al. 1999. Human gamma delta T cells recognize alkylamines derived from microbes, edible plants, and tea: Implications for innate immunity. Immunity, 11 (1), 57–65. URL (abstract): (accessed 09.29.2009).

Nakayama, M., et al. 1993. Inhibition of the infectivity of influenza virus by tea polyphenols. Antiviral Res., 21 (4), 289–299. URL (abstract): (accessed 10.14.2009).

See also:

  Brigham and Women’s Hospital. 2003. Press Release. Drinking tea may boost immune system. Study provides new theory on health benefits of tea — a cup a day may keep illness away. URL: (accessed 09.29.2009).

2 Jariwalla, R., et al. 2007. Suppression of influenza A virus nuclear antigen production and neuraminidase activity by a nutrient mixture containing ascorbic acid, green tea extract and amino acids. Biofactors, 31 (1), 1–15. URL (abstract): (accessed 09.29.2009).

3 Xiao, X., et al. 2008 [Antiviral effect of epigallocatechin gallate (EGCG) on influenza A virus]. Zhongguo Zhong Yao Za Zhi, 33 (22), 2678–82. URL (abstract): (accessed 09.29.2009).

4 Song, J., et al. 2005. Antiviral effect of catechins in green tea on influenza virus. Antiviral Res., 68 (2), 66–74. URL (abstract): (accessed 09.29.2009).

  Nakayama, M., et al. 1993. Inhibition of the infectivity of influenza virus by tea polyphenols. Antiviral Res., 21 (4), 289–299 (abstract). URL: (accessed 09.29.2009).

5 Sharma, M., et al. 2009. Induction of multiple pro-inflammatory cytokines by respiratory viruses and reversal by standardized Echinacea, a potent antiviral herbal extract. Antiviral Res., 83 (2), 165–170. URL (abstract): (accessed 09.29.2009)

  Roxas, M., & Jurenka, J. 2007. Colds and influenza: A review of diagnosis and conventional, botanical, and nutritional considerations. Altern. Med. Rev., 12 (1), 25–48. URL (PDF): (accessed 09.25.2009).

  Bodinet, C., et al. 2002. Effect of oral application of an immunomodulating plant extract on influenza virus type A infection in mice. Planta Med., 68 (10), 896–900. URL: (accessed 09.29.2009)

6 Linde, K., et al. 2006. Echinacea for preventing and treating the common cold. Cochrane Database Syst. Rev. (1), CD000530. URL (abstract): (accessed 09.30.2009).

7 Harris, J., et al. 2001. Antimicrobial properties of Allium sativum (garlic). Appl. Microbiol. Biotechnol., 57 (3), 282–286. URL (abstract): (accessed 09.30.2009).

8 Fujisawa, H., et al. 2009. Antibacterial potential of garlic-derived allicin and its cancellation by sulfhydryl compounds. Biosci. Biotechnol. Biochem., 73 (9), 1948–1955. URL: (accessed 09.30.2009).

  Ankri, S., & Mirelman, D. 1999. Antimicrobial properties of allicin from garlic. Microbes Infect., 1 (2), 125–129. URL (abstract): (accessed 09.30.2009).

  Weber, N., et al. 1992. In vitro virucidal effects of Allium sativum (garlic) extract and compounds. Planta Med., 58 (5), 417-423. URL (astract): (accessed 09.30.2009).

  Adetumbi, M., & Lau, B. 1983. Allium sativum (garlic) — a natural antibiotic. Med. Hypotheses, 12 (3), 227-237. URL: (accessed 09.30.2009).

9 Lissiman, E., et al. 2009. Garlic for the common cold. Cochrane Database Syst Rev., 8 (3) CD006206. URL (abstract): (accessed 09.30.2009).

  Weber, N., et al. 1992. In vitro virucidal effects of Allium sativum (garlic) extract and compounds. Planta Med., 58 (5), 417-423. URL (abstract): 09.30.2009).

10 [No author or date of publication listed.] Garlic facts (Allium sativum). Planet Botanic Canada. URL: (accessed 09.30.2009).

11 Bjarnsholt, T., et al. 2005. Garlic blocks quorum sensing and promotes rapid clearing of pulmonary Pseudomonas aeruginosa infections. Microbiology, 151 (Pt. 12), 3873–3880. URL: 3 (accessed 09.30.2009).

12 Andrianova, I., et al. 2003. [Effect of long-acting garlic tablets “Allicor” on the incidence of acute respiratory viral infections in children.] Ter. Arkh., 75 (3), 53–56. URL (abstract): (accessed 09.30.2009).

  Ankri, S., & Mirelman, D. 1999.

  Weber, N., et al. 1992.

13 Heimer, K., et al. 2009. Examining the evidence for the use of vitamin C in the prophylaxis and treatment of the common cold. J. Am. Acad. Nurse Pract., 21 (5), 295–300. URL: (accessed 09.30.2009).

  Douglas, R., et al. 2007. Vitamin C for preventing and treating the common cold. Cochrane Database Syst. Rev. (3), CD000980. URL (abstract): (accessed 09.30.2009).

  Linus Pauling Institute at Oregon State University. 2006. LPI Research Newsletter — vitamin C and the common cold. URL: (accessed 09.30.2009).

  Hemilä, H. 1994. Does vitamin C alleviate the symptoms of the common cold? — A review of current evidence. Scand. J. Infect. Dis., 26 (1), 1-6. URL (abstract): (accessed 09.30.2009).

14 Li, W., et al. 2006. Vitamin C deficiency increases the lung pathology of influenza virus-infected gulo-/- mice. J. Nutr., 136 (10), 2611–2616. URL: (accessed 09.30.2009).

  Furuya, A., et al. 2008. Antiviral effects of ascorbic and dehydroascorbic acids in vitro. Int. J. Mol. Med., 22 (4), 541–545. URL: (accessed 09.30.2009).

15 Rosner, F. 1980. Therapeutic efficacy of chicken soup. Chest, 78 (4), 672–674. URL: (accessed 09.30.2009).

16 Rennard, B., et al. 2000. Chicken soup inhibits neutrophil chemotaxis in vitro. Chest, 118 (4), 1150–1157. URL: (accessed 09.30.2009).

  Saketkhoo, K., et al. 1978. Effects of drinking hot water, cold water, and chicken soup on nasal mucus velocity and nasal airflow resistance. Chest, 74, 408–410. URL (PDF): (accessed 09.30.2009).

References on herbs for cold and flu season

1) Astragalus

Roxas, M., & Jurenka, J. 2007. Colds and influenza: A review of diagnosis and conventional, botanical, and nutritional considerations. Altern. Med. Rev., 12 (1), 25–48. URL (PDF): (accessed 09.25.2009).

Brush, J., et al. 2006. The effect of Echinacea purpurea, Astragalus membranaceus and Glycyrrhiza glabra on CD69 expression and immune cell activation in humans. Phytother. Res., 20, 687–695. URL (abstract): (accessed 09.25.2009).

McKenna, D., et al. 2002. Astragalus. Altern. Ther. Health Med, 8 (6), 34–40. URL (no abstract available): (accessed 09.25.2009).

Kajimura, K., et al. 1996. Protective effect of Astragali radix by oral administration against Japanese encephalitis virus infection in mice. Biol. Pharm. Bull., 19 (9), 1166–1169. URL (abstract): accessed 09.25.2009).

2) Black elderberry

Roxas M., & Jurenka, J. 2007.

Zakay–Rones, Z., et al. 2004. Randomized study of the efficacy and safety of oral elderberry extract in the treatment of influenza A and B virus infections. J. Int. Med. Res., 32 (2), 132–140. URL (abstract): (accessed 09.25.2009).

Blumenthal, M. 1998. The Complete German Commission E Monograph, 124. Austin, TX: American Botanical Council.

Zakay–Rones, Z., et al. 1995. Inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (Sambucus nigra L.) during an outbreak of influenza B Panama. J. Altern. Complement. Med., 1, 361–369. URL: (accessed 09.25.2009).

3) Cordyceps

Cheung, J., et al. 2009. Cordysinocan, a polysaccharide isolated from cultured Cordyceps, activates immune responses in cultured T-lymphocytes and macrophages: Signaling cascade and induction of cytokines. J. Ethnopharmacol., 124 (1), 61–68. URL (abstract): (accessed 09.25.2009).

Li, C., et al. 2009. Two-sided effect of Cordyceps sinensis on dendritic cells in different physiological stages. J. Leukoc. Biol., 85. [Epub ahead of print.] URL (PDF): (accessed 03.16.2009).

Park, D., et al. 2008. Immunoglobulin and cytokine production from mesenteric lymph node lymphocytes is regulated by extracts of Cordyceps sinensis in C57BI/6N mice. J. Med. Food, 11 (4), 784–787. URL (abstract): (accessed 02.26.2009).

Patterson, R. 2008. Cordyceps: A traditional Chinese medicine and another fungal therapeutic biofactory? Phytochemistry, 69 (7), 1469–1495. URL (abstract): (accessed 03.16.2009).

Wang, X., et al. 2008. [Intervening and therapeutic effect of Cordyceps mycelia extract on liver cirrhosis induced by dimethylnitrosamine in rats.] Zhongguo Zhong Xi Yi Jie He Za Zhi, 28 (7), 617–622. URL (abstract): (accessed 02.26.2009).

Yoon, T., et al. 2008. Innate immune stimulation of exo-polymers prepared from Cordyceps sinensis by submerged culture. Appl. Microbiol. Biotechnol., 80 (6), 1087–1093. URL (abstract): (accessed 02.26.2009).

Zhou, X., et al. 2008. Cordycepin is an immunoregulatory active ingredient of Cordyceps sinensis. Am. J. Chin. Med., 36 (5), 967–980. URL (abstract): (accessed 02.26.2009).

Ko, K., & Leung, H. 2007. Enhancement of ATP generation capacity, antioxidant activity and immunomodulatory activities by Chinese Yang and Yin tonifying herbs. Chin. Med., 2 (1), 3. URL: (accessed 08.12.2009).

Kuo, C., et al. 2007. Abrogation of streptococcal pyrogenic exotoxin B-mediated suppression of phagocytosis in U937 cells by Cordyceps sinensis mycelium via production of cytokines. Food Chem. Toxicol., 45 (2), 278-285. URL (abstract): (accessed 03.16.2009).

Koh, J., et al. 2002. Activation of macrophages and the intestinal immune system by an orally administered decoction from cultured mycelia of Cordyceps sinensis. Biosci. Biotechnol. Biochem., 66 (2), 407–411. URL: (accessed 09.25.2009).

Weng, S., et al. 2002. Immunomodulatory functions of extracts from the Chinese medicinal fungus Cordyceps cicadae. J. Ethnopharmacol., 83 (1–2), 79–85. URL (abstract): (accessed 09.25.2009).

Kuo, Y., et al. 2001. Regulation of bronchoalveolar lavage fluids cell function by the immunomodulatory agents from Cordyceps sinensis. Life Sci., 68 (9), 1067–1082. URL (abstract): (accessed 09.25.2009).

4) Echinacea

Sharma, M., et al. 2009. Echinacea as an antiinflammatory agent: The influence of physiologically relevant parameters. Phytother. Res., 23 (6), 863–867. URL (abstract): (accessed 09.25.2009).

Sharma, M., et al. 2009. Induction of multiple pro-inflammatory cytokines by respiratory viruses and reversal by standardized Echinacea, a potent antiviral herbal extract. Antiviral Res., 83 (2), 165–170. URL: (accessed 09.25.2009).

Senchina, D., et al. 2009. Echinacea tennesseensis ethanol tinctures harbor cytokine- and proliferation-enhancing capacities. Cytokine, 46 (2), 267–272. URL: (abstract): (accessed 09.25.2009).

Altamirano–Dimas, M., et al. 2007. Modulation of immune response gene expression by Echinacea extracts: Results of a gene array analysis. Can. J. Physiol. Pharmacol., 85 (11), 1091–1098. URL: (accessed 09.25.2009).

Roxas M., & Jurenka, J. 2007.

Tierra, M. 2007. Echinacea: An effective alternative to antibiotics. J. Herb Pharmacother., 7 (2), 79–89. Review. URL (abstract): (accessed 09.25.2009).

Classen, B., et al. 2006. Immunomodulatory effects of arabinogalactan-proteins from Baptisia and Echinacea. Phytomedicine, 13, 688-694. URL (abstract): (accessed 09.25.2009)

Block, K., & Mead, M. 2003. Immune system effects of Echinacea, ginseng, and Astragalus: A review. Integr. Cancer Ther., 2 (3), 247–267. URL (abstract): (accessed 09.25.2009).

Randolph, R., et al. 2003. Regulation of human immune gene expression as influenced by a commercial blended Echinacea product: Preliminary studies. Exp. Biol. Med. (Maywood), 228 (9), 1051–1056. URL: (accessed 09.25.2009).

Kim, L., et al. 2002. Immunological activity of larch arabinogalactan and Echinacea: A preliminary, randomized, double-blind, placebo-controlled trial. Altern. Med. Rev., 7, 138–149. URL (abstract): (accessed 09.25.2009).

Blumenthal, M. 1998. The Complete German Commission E Monographs, 122–123. Austin, TX: American Botanical Council. (accessed 09.25.2009).

Murray, M., & Pizzorno, J. 1998. Encyclopedia of Natural Medicine, 2nd ed., 159–160. Rocklin, CA: Prima Publishing.

Murray M. 1995. The Healing Power of Herbs, 2nd ed., 92–107. Rocklin, CA: Prima Publishing.

Bauer R., & Wagner, H. 1991. Echinacea species as potential immunostimulatory drugs. Econ. Med. Plant Res., 5, 253–321. In H. Wagner and N. Farnsworth (eds.), Economic and Medicinal Plant Research, Vol. 5. NY: Academic Press.

5) Eleuthero

Jung, C., et al. 2007. Eleutherococcus senticosus extract attenuates LPS-induced iNOS expression through the inhibition of Akt and JNK pathways in murine macrophage. J. Ethnopharmacol., 113 (1), 183–187. URL (abstract): (accessed 03.12.2009).

Roxas M., & Jurenka, J. 2007.

Narimanian, M., et al. 2005. Impact of Chisan (ADAPT-232) on the quality-of-life and its efficacy as an adjuvant in the treatment of acute non-specific pneumonia. Phytomedicine, 12 (10), 723–729. URL (abstract): (accessed 03.12.2009).

Narimanian, M., et al. 2005. Randomized trial of a fixed combination (Kan Jang) of herbal extracts containing Adhatoda vasica, Echinacea purpurea and Eleutherococcus senticosus in patients with upper respiratory tract infections. Phytomedicine, 12 (8), 539–547. URL (abstract): (accessed 03.12.2009).

Kimura, Y., & Sumiyoshi, M. 2004. Effects of various Eleutherococcus senticosus cortex on swimming time, natural killer activity and corticosterone level in forced swimming stressed mice. J. Ethnopharmacol., 95 (2–3), 447–453. URL (abstract): (accessed 03.12.2009).

Arushanian, E., et al. 2003. [Effect of Eleutherococcus on short-term memory and visual perception in healthy humans.] Eskp. Klin. Farmakol., 66 (5), 10–13. URL (abstract): (accessed 03.12.2009).

Rogala, E., et al. 2003. The influence of Eleutherococcus senticosus on cellular and humoral immunological response of mice. Pol. J. Vet. Sci., 6 (Suppl.), 37–39. URL (abstract): (accessed 03.12.2009).

Drozd, J., et al. 2002. Estimation of humoral activity of Eleutherococcus senticosus. Acta Pol. Pharm., 59 (5), 395–401. URL (abstract): (accessed 03.12.2009).

Panossian, A., et al. 2002. Effect of andrographolide and Kan Jang — fixed combination of extract SHA-10 and extract SHE-3 — on proliferation of human lymphocytes, production of cytokines and immune activation markers in the whole blood cells culture. Phytomedicine, 9 (7), 598–605. URL (abstract): (accessed 03.12.2009).

Schmolz, M., et al. 2001. The synthesis of Rantes, G-CSF, IL-4, IL-5, IL-6, IL-12 and IL-13 in human whole-blood cultures is modulated by an extract from Eleutherococcus senticosus L. roots. Phytother. Res., 15 (3), 268–270. URL (abstract): (accessed 03.12.2009).

Davydov, M., & Krikorian, A. 2000. Eleutherococcus senticosus (Rupr. & Maxim.) Maxim. (Araliaceae)as an adaptogen: A closer look. J.Ethnopharmacol., 72 (3), 345–393. URL (abstract): (accessed 03.12.2009).

Farnsworth, N., et al. 1985. “Siberian ginseng (Eleutherococcus senticosus): Current status as an adaptogen.” In Economic and Medicinal Plant Research. Vol. 1, eds. H. Wagner et al., 217-284. London: Academic Press.