Cold and flu season runs from December to March each year, and while you can pick up a respiratory viral infection at any time, it is most likely to happen during this time. Over 100 types of the virus cause the common cold (Rhinoviruses), and three influenza viruses (types A, B and C) cause flu. Both cold and flu are classed as upper respiratory tract infections and may cause sore throats, coughs, a runny nose, headaches, low energy, an aching body, chills and shaking. Flu may induce a moderate to high fever and constant tiredness, and it can develop into more severe conditions like pneumonia. The symptoms we associate with cold and flu result from the immune system working to clear the virus.


Supporting the Immune System

For cold and flu viruses (and any others for that matter) to be successful, they need to get into the body and replicate. Viruses can be inhaled, ingested, transmitted from mother to child (vertical transmission) or through some other means of intimate physical contact. Once in the body, it must hijack your cell’s machinery to make copies of itself since it cannot do this itself. While doing this, the virus will also need to evade the body’s immune system and do this long enough to infect another human or establish itself in the body of the original human. The raison d’etre of all viruses is to reproduce. It’s the only thing they are designed to do. So, an antiviral strategy has to consider the various stages of the infection process to prevent and treat infection and support recovery post-infection.

Antiviral Immune Health Strategies

Several antiviral strategies effectively reduce cold and flu symptoms’ frequency, severity, or duration. 



Effective prevention of viral infection involves two key strategies. Preventing viral entry and ensuring nutrition and lifestyle status is optimal. 

Preventing Viral Entry

Remember during the pandemic when everyone was fastidiously washing their hands, covering their mouths when coughing and sneezing and encouraging well-ventilated rooms and buildings? Sadly, those hygiene habits disappeared as quickly as they arrived! Hand hygiene and coughing etiquette are essential strategies to prevent viral invasion as they cover two key routes of viral entry – inhalation and ingestion.

Once the virus has made it into a bodily opening, it needs to pass through the tightly packed “shield wall” barricade of epithelial cells; these cells line all of the body’s openings, such as the nose, mouth, lungs, oesophagus and gut and are often referred to as the mucosa. Special glands in the mucosa secrete mucus, a further barrier against invasion. The mucus traps and neutralises pathogens at the barrier interface so they can’t get into the body and cause chaos. Maintaining healthy mucosal barriers is essential. Therefore, a critical preventative strategy is ensuring optimal vitamin A levels. Vitamin A maintains barrier function by directly controlling the growth of barrier cells in the gut, the nose and the respiratory tract, which can be damaged by viral infiltration. 


Nutrition and Lifestyle Status

Nutritional status is a crucial factor in viral replication and the ability of an invader to cause disease. Ideally, you want a lifestyle that supports cellular health. So what does this look like? It’s everything we discuss in this article. First and foremost, you want to ensure you get restorative sleep, followed by managing stress. These are fundamental; no supplement will give your body what a good quality night’s sleep can give your body. Being overtired or not sleeping well will increase stress hormones, reducing the number of T cells in circulation and making the ones there less effective. You’ll also want to make sure that you’re moving – like we humans were designed to – but not over-exercising, as this is a significant stressor for the body. Movement allows lymph to move, clearing cellular debris and providing the cell with the needed fluids. Finally, nutrition that is supportive of the immune system is rich in diverse plant foods that support the gut microbiome and mucosal integrity, provides the right balance of food to ensure a stable blood sugar response  so as not to drive inflammation, provides the nutrients that support the powerhouse of the cell (mitochondria) as a fully activated immune response is very energy expensive.  

Winter Health Toolkit



If a virus passes the barrier interface, the innate immune system responds quickly and is a broad spectrum. It includes a range of white blood cells and chemicals that eliminate anything foreign. The adaptive immune system kicks in if the innate immune system cannot get the invasion under control within five days. Several natural compounds can be used as antiviral agents to support proper immune function.


Antiviral Agents



Free radicals are frequently produced during viral infections. However, when the production of free radicals overwhelms the body’s antioxidant defence system, it induces oxidative stress, leading to cellular damage. Free radicals can also enhance viral replication, amplifying the amount of virus in the body. Ensuring adequate selenium levels will help your body defend against viral infection and support recovery. 



Zinc is essential for mounting an effective antiviral response. It has direct antiviral properties against influenza and is crucial in generating an innate and acquired immune response. Ensuring adequate zinc levels is valuable in supporting the immune system in the lead-up to viral infections. Zinc can also be used therapeutically at the time of infection and during recovery. Being tired, stressed, or pregnant could lead to inadequate levels of zinc in the body.



Elderberry has been used against cold and flu infections and as an antiviral support for a long time, and there is a lot of good evidence to support its use in adults and children. Elderberry can shorten the duration of infection and reduce symptoms in upper respiratory tract infections. It can also be used preventively at the start of cold and flu season and maintained at low levels consistently throughout the season.



Historically, liquorice was used in ancient China, India and Greece to support the management of symptoms associated with respiratory virus infections. Researchers worldwide have reported on its antiviral, antimicrobial, anti-diabetic, antioxidant, and anti-inflammatory properties at low-appropriate doses. Liquorice reduces the ability of the new viruses to infect additional cells. However, liquorice could be harmful if you have high blood pressure, are pregnant or thinking about becoming pregnant or are taking any prescription medications.



Quercetin, found in apples, onions, and grapes, is a good choice for chronically inflamed individuals, such as those with hay fever or allergies, who experience mould problems or are living with inflammatory conditions. Quercetin has a wide range of properties and can be used as part of an antiviral strategy during viral infection.


Vitamin D

Vitamin D is essential for regulating the immune system and enhancing the innate immune response. It also influences the ability of immune cells, particularly to respond when needed and switch off when not required. Like other vitamins and minerals, vitamin D is used up during viral infection, so monitor levels through testing to maintain appropriate levels.


Infection with viruses will deplete vitamins and minerals while increasing the demand for them, so it’s vital to put back what will have been used to fight the infection in the recovery phase.


Alongside restoring vitamin and mineral status, you’ll also want to ensure that you prioritise sleep, balance inflammation through diet and critical nutrients, balance stress, avoid alcohol and increase the diversity and colour of plant foods to support the gut microbiome.

The Upshot

Several natural compounds can effectively reduce the frequency, severity, or duration of cold and flu symptoms. 


It’s important to remember that herbs and foods are complex and contain multiple chemicals and compounds that positively affect the body. While we know that many provide benefits for immune health, the complexity means we don’t always understand how this is achieved.