During the winter months, the body’s immune system is placed under increased stress and becomes more vulnerable to infection.¹ Supporting immunity during the colder winter months may help to reduce the risk of infection and aid recovery.

Which herbs and nutrients are best for preventing and treating acute colds and flus?

Andrographis (Andrographis paniculata) has been used traditionally to treat fever and infections, especially of the respiratory tract, including the common cold, influenza, throat infections, bronchitis, and cough.² Meta-analysis data, examining the results of many clinical trials, has shown that Andrographis supplementation can improve the symptoms and shorten the duration of upper respiratory tract infections.^3,4

Reishi (Ganoderma lucidum) is one of the oldest, most revered medicinal mushrooms on record and is often referred to as the ‘mushroom of immortality’.⁵ A randomised controlled trial found that supplementation with Reish significantly increased immune cells involved in immune defence in healthy adults, which is likely to enhance their resistance to opportunistic infections such as colds and coughs.⁶

Vitamin C has been shown to have an important immune-stimulating role. In a meta-analysis of ten placebo-controlled trials, vitamin C supplementation resulted in a statistically significant reduction in severity and duration of the common cold compared to placebo.⁷ Bioflavonoids are always found with vitamin C in food sources and provide antioxidant protection whilst potentiating the effects of vitamin C supplementation.⁸

Vitamin A plays a crucial role in the development and function of the immune system. Deficiency of vitamin A is associated with a high incidence of respiratory tract infections in children,⁹ while supplementation of vitamin A reduces the morbidity and mortality from infectious diseases.¹⁰

Vitamin D enhances innate immune responses. Epidemiological studies suggest that low vitamin D status appears to increase the risk of respiratory infection. A meta-analysis of 46 studies including 75,541 participants found that supplementation with vitamin D significantly reduced the risk of acute respiratory infection compared to placebo.¹¹

Zinc is essential for optimal immune system functioning. Increased susceptibility to infections is a consistently reported symptom of suboptimal zinc intake.¹² Supplementation with zinc may reduce the symptoms and shorten the duration of the common cold in meta-analyses data.^13,14

Which herbs and nutrients can be used for the prevention of acute and chronic recurrent illnesses?

Cat’s Claw (Uncaria tomentosa) a is a woody vine native to the Amazon rainforest. It is traditionally administered for infections, convalescence or debility. It is well regarded as an immune rejuvenating tonic or restorative herb. In vitro and in vivo studies have confirmed its immune modulating, antimicrobial, antiviral and antiprotozoal effects.^15,16

Echinacea (Echinacea spp.) root first came from Native American tribes, before being adopted by Eclectic physicians and used to treat an extensive range of conditions, including infections.¹⁷ Nowadays, Echinacea is widely used as a preventive or early treatment for the common cold.¹⁸ Meta analysis confirms that Echinacea can significantly reduce the risk of respiratory tract infections.¹⁹ Supplementation also significantly reduced incidence of infection in children with recurrent tonsillitis.²⁰

Astragalus (Astragalus membranaceus) root exhibits potent immune and antiviral properties.²¹ It is frequently prescribed in states of chronic immune depletion to promote healing, aid recovery from infections, and aiding convalescence.^22,23 Clinical studies have found that Astragalus supplementation can improve white cell counts in patients with leukopenia;²⁴ and reduce the incidence of respiratory tract infection in children with nephrotic syndrome.²⁵

Olive leaf (Olea europaea) has been used as a traditional medicine in the Mediterranean for many years. In vitro evidence shows immune-modulatory activity, including increased natural Killer cell and interferon-γ activity.²⁶ A clinical trial found Olive Leaf extract significantly reduced sick days by 28% and decreased the duration of respiratory infections in high school athletes when taken daily for two months.²⁷

What does convalescence mean?

Convalescence is the gradual recovery of health and strength after an illness. Proper convalescence requires adequate rest, nourishing food, gentle exercise, and restorative herbs to aid full recovery and protection against recurrent illness. Above all, convalescence requires time, a precious commodity in our modern world.²⁸

Which herbs are best for viral infections?

Elderberry (Sambucus nigra) Elderberry has gained popularity for the treatment of the common cold due to its potent antiviral,²⁹ and immune-modulating properties.³⁰ Research suggests that Elderberry may exert antiviral activity against a range of viruses including rhinovirus, RSV,³¹ influenza A and B,^81,84,32,33 A meta-analysis demonstrated that Elderberry significantly reduces upper respiratory symptom duration inpatients with influenza or the common cold.³⁴

Which herbs are best for bacterial infections?

Garlic (Allium sativum),³⁵ Nigella (Nigella sativa),³⁶ Phellodendron (Phellodendron amurense),³⁷ Cinnamon (Cinnamomum verum),³⁸ and Thyme (Thymus vulgaris)³⁹ have all demonstrated antibacterial activity against human pathogens.

Should supplements be taken every day?

Herbs and nutrients for the prevention of infection should be taken daily during the winter months for best results. Herbs and nutrients for the treatment of acute infections can be taken only as needed.¹⁷

References

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² Pharmacopoeia Commission of the People’s Republic of China. Pharmacopoeia of the people’s republic of China, English ed. Beijing: Chemical Industry Press; 1997.

³ Coon JT, Ernst E. Andrographis paniculata in the treatment of upper respiratory tract infections: a systematic review of safety and efficacy. Planta Med. 2004 Apr;70(4):293-8. DOI: 10.1055/s-2004-818938.

⁴ Hu X, Wu R, Logue M, Blondel C, Lai LYW, Stuart B, et al. Andrographis paniculata (Chuān Xīn Lián) for symptomatic relief of acute respiratory tract infections in adults and children: A systematic review and meta-analysis. PLoS ONE. 2017 Aug 4;12(8):e0181780. DOI:10.1371/journal.pone.0181780

⁵ Venturella G, Ferraro V, Cirlincione F, Gargano ML. Medicinal mushrooms: bioactive compounds, use, and clinical trials. Int J Mol Sci. 2021 Jan;22(2):634. DOI: 10.3390/ijms22020634

⁶ Chen SN, Nan FH, Liu MW, Yang MF, Chang YC, Chen S. Evaluation of immune modulation by β-1,3; 1,6 D-glucan derived from Ganoderma lucidum in healthy adult volunteers, a randomized controlled trial. Foods. 2023 Feb;12(3):659. DOI: 10.3390/foods12030659

⁷ Hemilä H, Chalker E. Vitamin C reduces the severity of common colds: a meta-analysis. BMC Public Health. 2023 Dec 11;23(1):2468. DOI:10.1186/s12889-023-17229-8

⁸ Health Canada. Citrus Bioflavonoids monograph. Ottowa, Ontario; Government of Canada: 2024. Available from 

https://webprod.hc-sc.gc.ca/nhpid-bdipsn/atReq?atid=citrus.bioflav.agrumes&lang=eng

⁹ Zhang X, Dai X, Li X, Xie X, Chen Y, Chen Y, et al. Recurrent respiratory tract infections in children might be associated with vitamin A status: a case-control study. Front Pediatr. 2024 Jan 5;11:1165037. DOI:10.3389/fped.2023.1165037

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¹¹ Jolliffe DA, Camargo CA, Sluyter JD, Aglipay M, Aloia JF, Ganmaa D, et al. Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomised controlled trials. The Lancet Diabetes & Endocrinology. 2021 May;9(5):276-92. DOI:10.1016/S2213-8587(21)00051-6

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¹⁴ Hunter J, Arentz S, Goldenberg J, Yang G, Beardsley J, Myers SP, et al. Zinc for the prevention or treatment of acute viral respiratory tract infections in adults: a rapid systematic review and meta-analysis of randomised controlled trials. BMJ Open. 2021 Oct;11(11):e047474. DOI:10.1136/bmjopen-2020-047474

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