Fending off viral invaders
Heidi Fritz, MA, ND
The dreaded cold and flu season is upon us. And with the commencement of the new school year, what could be a higher priority than staying healthy this fall and winter? A number of natural health products (NHPs) are available to help support healthy immune function and exert antiviral effects. We look at the most appropriate uses of supplements such as vitamins, probiotics, and herbal preparations to fight the cold and flu.
The common cold is an infection of the upper respiratory tract with symptoms including runny nose; headache; sore throat; cough; and an overall feeling of weakness, discomfort, or just not feeling well.
The cold is caused by several viruses, including rhinoviruses, adenoviruses, paramyxoviruses, and coronaviruses. Ear pain or ear infection may follow the common cold in children.
Influenza, or “the flu,” is caused by the influenza virus, and symptoms are similar to a cold, though typically more severe, including fever, chills, headache, runny nose, cough, weakness, discomfort, and feeling of being unwell.
Complications of influenza include ear infections, pneumonia, secondary bacterial infections, exacerbations of chronic respiratory disease, and bronchiolitis in children.
Transmission of both illnesses is through direct hand contact with the secretions from an infected person (either directly or from surfaces like a doorknob) or through inhalation of respiratory secretions and viruses.
These can be divided into two groups: immune modulators and antimicrobials. We can tailor the use of these NHPs based on the stage of illness. While the common cold and flu are caused by different viruses, management with NHPs is similar for both.
Immune modulators strengthen the immune system’s ability to fight infection. For instance, herbs in this category may increase the antiviral activity of T-lymphocytes, natural killer (NK) cells, and other immune cells.
Antimicrobial agents have direct effects by killing the bacteria or virus, often by causing damage to the bacterial membrane or viral envelope.
Antibiotics are effective against bacteria only and should not be used to treat viral illnesses such as the cold and flu.
Vitamin C, vitamin D, and probiotics function as immune modulators.
A 2015 Cochrane meta-analysis evaluated 12 studies and 3,720 participants, including children. Results showed that supplementation with probiotics was superior to placebo for reducing
Among those with vitamin D deficiency, supplementation is consistently associated with benefit to immunity. Daily vitamin D supplementation has been shown to reduce incidence of influenza A in schoolchildren.
In addition, a randomized trial of 400 infants found that high-dose vitamin D reduced the incidence of influenza A compared to the low-dose vitamin D group (78 versus 43 cases). Duration of fever, cough, and wheezing was shorter and the viral loads decreased more rapidly in the high-dose group.
Garlic (Allium sativa), Echinacea species, and elderberry (Sambucus nigra) extracts have been shown to exert potent antiviral effects.
A randomized trial of 120 adults found that aged garlic extract increased T-lymphocytes and NK cells and reduced the severity and duration of cold and flu symptoms. Garlic contains allicin, which has been shown to kill viruses such as rhinovirus and parainfluenza virus.
A randomized trial of 473 patients with early influenza symptoms (less than 48 hours) found that a daily combination echinacea and elderberry extract for 10 days was as effective as the prescription flu medication oseltamivir for reducing the duration of illness and had fewer side effects.
The majority of viral respiratory disease is influenza‐like illness (ILI), which is caused by many different viruses that are not clinically distinguishable from one another without testing. Only about 7 to 15 percent of ILI is caused by actual influenza viruses and is known as influenza.
Another meta-analysis found that vitamin C was less effective for preventing the common cold, but better in reducing its severity and duration. In an analysis of 29 trials involving 11,306 participants, researchers found that vitamin C reduced duration of colds by 8 percent in adults and 14 percent in children. The severity of colds was also significantly reduced.
Finally, a recent meta-analysis including 180 participants found that Sambucus nigra (black elderberry) was found to “substantially reduce upper respiratory symptoms.” Authors concluded that elderberry may be a “potentially safer alternative to prescription drugs for routine cases of the common cold and influenza.”
Individuals who are having difficulty getting back on their feet after the cold or flu may wish to consider continuing supplementation with vitamin C, vitamin D, and probiotics, and may also benefit from use of Astragalus membranaceous.
Astragalus is an immune tonic herb and an adaptogen for the immune system. Astragalosides, a major active component, have immune-regulatory and anti-inflammatory effects, including inducing T-cells, regulating effector/regulatory T-cell balance, and inhibiting pro-inflammatory cytokines.
Be sure to check with your health care practitioner to determine the treatments and dosages that are best for you.
Dr. Heidi Fritz, MA, ND, is a research fellow and practises at the Bolton Naturopathic Clinic and the Springdale Medical Centre in Brampton, Ontario. boltonnaturopathic.ca