Good health is one of the most valuable things we have, and our primary resource for a good life. This becomes most clear when we lack good health. A common cold or the flu can make everyday tasks seem like a huge burden. Even a mild bout of the sniffles can throw a wrench into our daily routine, especially when we have to take a couple of days off to recover.

While there are many ways that can help us to recover from sickness faster, the best way to fight illness is to prevent it. Here are a couple of tips for balancing and strengthening your immune system.



Regular physical activity is one of the most important things you can do for your health. It may sound surprising but physical inactivity has been identified as the fourth leading risk factor for global mortality, accounting for more than 5 million deaths per year. According to the World Health Organization, people who are insufficiently active have a 20% to 30% increased risk of death compared to people who are sufficiently active. 1, 2, 3, 4

But it’s not just about keeping disease and premature death at bay. There are several hundred studies that showed the benefits of physical activity in improving life quality through enhanced self-esteem, increased vitality and energy, improved mood, reduced anxiety, resilience to stress, and yes …. it is one of the key elements of a strong immune system!1-16

In a study published in the British Journal of Sports Medicine, researchers found that the number of days with upper respiratory tract infection during a 12-week period was reduced by 43% in subjects reporting 5 or more days per week of aerobic exercise compared to those who were largely sedentary (1 or less day per week). In addition, the severity and symptomatology of the infections were reduced by 32%!16

ADDITIONAL NOTE: Please also note that the relationship between exercise and respiratory tract infections follows a J-shaped curve. This means that regular moderate physical activity decreases the relative risk of infection below that of a sedentary individual. However, excessive amount of very high intensity exercise can increase risk of infection. Thus, during periods of strenuous exercise, you should be especially aware to your immune system! Immunonutrition support for highly active individuals and athletes is a rapidly expanding area of scientific investigation, and vitamin C is one of the most widely researched nutrients as countermeasures to exercise-induced immunosuppression.

Studies have shown vitamin C supplementation (e.g., 500-600 mg/day) to be effective in reducing symptoms of respiratory tract infections during periods of intense exercise. 17-24 In a particular study, researchers found that athletes who took supplementary vitamin C (600mg/day) reported significantly less upper respiratory tract infections compared to non-supplementing athletes (33% vs. 68%). 24



Adequate consumption of vegetables and fruit are vitally important to human health! In fact, inadequate consumption of vegetables and fruit contributed to more than 3.8 million deaths in 2016!26

A review of 95 studies, found that there was a 16% reduction in the risk of heart disease, a 28% reduction in the risk of stroke, a 22% reduction in the risk of cardiovascular disease, a 13% reduction in the risk of cancer, and a 27% reduction in the risk of all-cause mortality for an intake of 500 g of fruits and vegetables per day, compared to 0–40 grams per day.26-28 Fruits and vegetables are a key contributor to a strong immune system!

In a study published in the American Journal of Clinical Nutrition, researchers found that antibody response to a given vaccination was significantly higher in the group that consumed 5 portions pf vegetables and fruit per day than in the 2-portion/day group. This suggests they contribute to improved immune function. 29

The World Health Organization (WHO) recommends eating at least five 80 g portions of fruit and vegetables every day (total 400 grams per day), and this should be the minimum!



Research conducted during the past decade suggest that both vitamin D and zinc deficiencies are widespread and affect the health and well-being of populations worldwide.

Vitamin D insufficiency is a major health problem with over one billion people affected worldwide. 34, 35 We can obtain vitamin D from our daily diet, and from synthesis in the skin by exposure to ultraviolet B irradiation from the sun. During wintertime, due to lack of sun exposure, vitamin D deficiency became much more common. Since vitamin D plays key roles as a natural immune modulator, its deficiency has profound effects on the immune system, and thus on susceptibility to infectious diseases. You probably realized that colds and flu tend to occur in the winter months, now you know the cause of this. In 1981, a British doctor, proposed that a “seasonal stimulus” directly associated with solar radiation may explain the seasonality of epidemic influenza, and this association was highlighted a quarter of century later when studies found that vitamin D status may be the “seasonal stimulus” for influenza.

In a study published in the Archives of Internal Medicine the researchers found that people with low blood vitamin D levels were 40 percent more likely to have reported a recent infection, compared with those who had the highest levels.36 On the other hand, studies proved that vitamin D supplementation may help protect against infections.

A review of 25 trials showed that vitamin D supplementation may boost immunity and cut rates of respiratory tract infections.38 One study found 70 % less incidence of cold and influenza symptoms were reported by those receiving 800 to 2000 IU of vitamin D daily during a 3-year follow-up, compared with the control group. Only one subject had cold/influenza symptoms while taking high doses of vitamin D (2000IU/day). 39, 40

Nutritional deficiency of zinc may affect as much as 2 billion people worldwide! According to the WHO the global prevalence of zinc deficiency was estimated at 31%.31, 32

According to the authorized health claims of the European Food Safety Authority (EFSA), zinc contributes to the normal function of the immune system.30 Zinc deficiency is associated with a decline in most aspects of immune, and renders people more susceptible to infections. On the other hand, zinc supplementation has shown benefits in immune responses to bacterial and viral infections. 30 On the top of that during inflammation, there is an increased cellular demand for zinc and impaired zinc homeostasis from zinc deficiency is associated with chronic inflammation.

A 2016 meta-analysis on common cold found that zinc supplementation decreased the duration of colds by 2.7 days, compared with the 7-day average duration of colds in the trials.33



The diverse collection of microorganisms that inhabit the gastrointestinal tract -collectively called the gut microbiota-, profoundly influences many aspects of host physiology, including resistance to infection and immune system functioning. The importance of immune modulation at the gastrointestinal level can be understood easily, considering that approximately 70% of the entire immune system is found in this site.41, 43

Twin studies have shown that, although there is a heritable component to gut microbiota, environmental factors related to diet, drugs, lifestyle factors, and even actual health status are larger determinants of microbiota composition. 42 Thus our modern lifestyle with widespread use of antibiotics, drugs, alcohol, infections, diarrhea, obesity, poor diet and stress have all been known to adversely influence the gut’s microbiome, and consequently cause a number of negative health effects, including systemic and intestinal inflammation, gastrointestinal diseases, immune disorders, liver and kidney disease, development of cancer (such as gastrointestinal cancer and prostate cancer), obesity, insulin resistance, and even alteration of behavior through the central nervous system.44-48

A number of clinical studies found that specific strains of probiotic bacteria, when consumed in adequate amounts, are able to modulate immune responses.49-55

A review published in the Cochrane Database of Systematic Reviews analyzing the results of 13 individual trials, found that probiotics supplementation exert beneficial effects in reducing the number of participants experiencing episodes of acute upper respiratory tract infections, as well as the mean duration of an episode of infection.54

In a particular 12-week trial, intake of a probiotic mixture, that contains 2 different Lactobacillus strains (L. plantarum and L. paracasei) reduced the incidence of acquiring one or more common cold episode by 18%, and the number of days with common cold symptoms by 28%.55



Sleep is vital to achieve and maintain optimal daily functioning, and long-term health. Sleep deprivation have been associated with the development of severe pathologies, including obesity, diabetes, and cardiovascular disease, several types of cancer. In fact, people consistently sleeping 5 hours or less per night may have a 12% increased risk of death.58-59

It has also been found that sleep itself has a sustentative role for the functioning of the immune system, whereas sleep loss is a risk factor for impaired immune function.56, 57 In our modern society, inappropriate sleep times are becoming highly frequent, and over the last 40 years, sleep disorders have become epidemic. Insomnia is reported in approximately 30% of adults worldwide. Aside from medical or psychological conditions, sleep disorders may relate to lifestyle factors such as being overweight, high stress levels, working >10h per day, smoking, excessive consumption of caffeinated beverages, and nutrient inadequacy.

Recommended sleep for adults is 7-9 hours per night, depending on our predecessors and on the mental and physical load of our daily life, because individual sleep need is both a heritable quantitative trait and a behaviorally influenced. If you want to build a strong immune system take care of your sleep quality and quantity. If you need a little help, read our previous article about a couple of supplements that may help to boost your sleep quality.


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