Immune System Support

Immune system support is always important but in today’s world, it is more important than ever to learn more about what you can do to improve health and support your immune system.

Outbreaks of viral infections, such as those that cause colds and flus, have long been associated with the changing seasons, reaching a peak in the winter months. Winter is just around the corner so try to do all you can to prevent them.

Influenza viruses (A and B) cause worldwide outbreaks seriously impacting public health. The official assessment adopted by the World Health Organization in 2017 states that influenza is associated with up to 650 000 deaths from respiratory causes alone.

The common cold is an acute, self-limiting viral infection of the upper respiratory tract; although more than 200 viruses have been implicated, rhinoviruses are responsible from 30-50% and 10-15% are caused by coronavirus

Currently, the preventions most people are following to prevent the spread of a contagious virus, may also help reduce the yearly incidence of colds and flus. Washing hands often is very important anytime but especially during cold and flu season.

However, there is always something more we can do to support our immune system:

Diet and your immune system

Like any fighting force, the immune system army marches on its stomach. Healthy immune system warriors need good, regular nourishment. So, what can you do? If you suspect your diet is not providing you with all your micronutrient needs —for instance, you don’t like or don’t eat enough fruit and vegetables — taking a daily multivitamin and mineral supplement or adding a green drink powder to a smoothie may bring other health benefits, as well as help to support the immune system.

Consuming too much sugar can negatively affect the immune system and increase low grade inflammation. Even consuming 75 to 100 grams of a sugar can hinder the body’s immune function –  the equivalent of two cans of your soda or a couple of large lattes.

Stress, loneliness, grief, smoking and sedentary lifestyle all decrease our ability to fight infection. Taking these factors into consideration, you may want to make some changes in your life where you can.

The Importance of the Microbiome for Colds and Flus

The microbiome is a very important participant in the development of immune response against various pathogens. In fact, more than 70% of the human immune system is found in the gut. In addition, the intestinal immune system contains more antibody-producing cells than the rest of the body put together. The crosstalk between the gut-lung axis also provides greater immunity for respiratory infections.

However the overuse of antibiotics, poor diet and lifestyle choices have weakened the microbiome immunity and led to a lack of resilience and strength required to establish immunity against influenza virus.

A probiotic cocktail offers targeted prevention. Studies show that these good bacteria significantly reduce the risk of getting upper respiratory tract infections, including colds and flus. And in those who do get sick, these probiotics reduce the severity and duration of the illness. Probiotics provide defense against the common cold and flu by activating the body’s own immune response.

Nutritional Support for Viral Infections

N-Acetyl-Cysteine (NAC)

The past decade has witnessed an explosion of data regarding the multifaceted benefits of NAC, including antioxidant, anti-inflammatory, and antimicrobial activities.

Clinical evidence shows NAC supplementation is effective in the prevention of chronic obstructive pulmonary disease (COPD) exacerbation and reducing influenza-virus symptoms.

Preliminary data also suggests that NAC and its antioxidant properties may have a purpose for use in the therapy and/or prevention of acute viral and bacterial respiratory infections.

Cysteine a part of NAC is very important for immune health because lymphocyte and other immune cell functions are strongly influenced by small variations in cysteine levels.

NAC was shown in an Italian study to help prevent symptoms of H1N1 flu in almost 2/3 of the people taking it, when compared to a placebo. Participants received either a placebo or NAC 600 milligrams twice a day for six months and those receiving the placebo, 79% developed symptoms of flu while of those taking NAC, only 25% developed symptoms.

Vitamin C

Vitamin C is an essential nutrient for humans and contributes to immune defense by supporting various cellular functions of the immune system. The human body does not produce vitamin C so it makes sense to supplement daily to ensure the body has the protection. Stress and aging tend to lower levels of vitamin C which can lead to impaired immune function.

Roughly 23% of North Americans have vitamin C depletion, causing their immune systems to not function properly. Studies show that doses of vitamin C at 1,000 mg per day can effectively improve the immune response.  

New studies confirm that vitamin C supplementation at 1,000 mg per day shortens the duration and mitigates the severity of colds, while also preventing colds from developing. Some research suggests higher doses of vitamin C (to bowel tolerance) may help prevent and or minimize viral infections.


Zinc deficiency can also be an increased risk for infections. Zinc has been shown to reduce the duration and severity of the common cold. A review of several studies demonstrated possible effectiveness of oral zinc supplementation for at least 5 months in preventing colds in children. Zinc lozenges have been shown to be effective in reducing the duration of symptoms in adults if initiated within 24 hours of symptom onset of a cold. Health Canada estimates that up to 35% of Canadians are getting insufficient levels of zinc in their diet. Many theorize that our soils are becoming depleted of minerals such as zinc, due to modern farming methods.

Vitamin D

Previous studies have reported an association between low levels of vitamin D and susceptibility to acute respiratory tract infections.

Approximately 32% of the Canadian population is vitamin D deficient with some populations having even higher levels of deficiency, including premenopausal women, those with poor nutrition habits, those who avoid even minimal sun exposure, and those who take prescription medication long term for heartburn, acid reflux, and constipation.

The elderly who are most at risk for respiratory infections are the most deficient in Vitamin D. A study found that 75% of people in institutions, such as hospitals and care homes, were severely deficient in vitamin D. Consider taking 2,000 IU of vitamin D daily. D is best absorbed with a fatty meal.

The supplements listed above are my top pics and in addition, elderberry and quercetin have also shown promise for influenza.


Commonly used for treating symptoms related to the flu. It has antioxidant and immune-modulating properties and in studies for influenza A and B elderberry was shown to reduce severity and duration of the flu.   


Data shows quercetin exerted an obvious inhibitory effect for both H1N1 and H3N2 influenza A virus strain infections.

Diet and lifestyle are the foundation for good health overall and nutritional support is important added insurance.

Disclaimer: there is not a current treatment for covid-19 and the supplements mentioned above have been studied for the prevention and treatment of influenza viruses and colds.


Karen Jensen was in clinical practice for 25 years and although she is retired, she continues to write books and educate on the naturopathic approach to wellness. She is author or co-author of seven books, her most recent is Women’s Health Matters: The Influence of Gender on Disease.

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