The state and functioning of our immune system during the colder months of the year—autumn and winter—has always been a topic of interest. However, since March 2020 and the emergence of COVID-19, it has gained even greater relevance at any time of year.
Given the circumstances we are living through, there is a great deal of confusion when it comes to distinguishing between the common cold, the flu and COVID-19. What is clear, however, is that we all want our immune system to be strong and in optimal condition in order to prevent infections, avoid discomfort, possible hospitalizations or sick leave—in short, to avoid anything that forces us to put our lives on hold.
In recent years, we have gained a great deal of information about how to assess the state of our immune system and how to support it. This has also led to many questions about the role of nutrition and dietary supplements in optimizing our immune defenses.
Before diving into nutrition and the scientific evidence supporting the use of certain micronutrients to strengthen the immune system, it is important to remember that there are also behavioral, nutritional and lifestyle strategies that help limit infections and prevent the transmission of pathogens.
Behavioral strategies are already very familiar to us and part of our daily routines:
- Minimizing contact with infected individuals.
- Wearing a mask in indoor spaces.
- Washing hands regularly, especially before meals and after contact with people or public spaces.
- Avoiding large crowds.
- Avoiding repeatedly touching shared public surfaces.
- Not sharing bottles, cutlery or utensils with others.
- Carrying hand sanitizer.
In addition, there are also nutritional and lifestyle strategies, such as maintaining a healthy diet rich in fruits and vegetables. Thanks to their high micronutrient content, these foods help ensure adequate intake of essential vitamins and minerals necessary for proper body function—and therefore for a well-functioning immune system.
We should also bear in mind that there is growing evidence supporting the importance of lifestyle and environmental exposures in maintaining a healthy immune system. Physical activity and overall fitness are considered factors that can reduce the risk of infection, even in people who have other risk factors such as hypertension or high cholesterol. It is never too late to start exercising or to increase daily movement: walk to work, take the stairs instead of the elevator, start with two or three exercise sessions per week. Small changes can make a meaningful difference in the medium to long term. Physical inactivity has been increasing over the years, and this trend is reflected in declining population health.
Finally, it is worth highlighting the role of vitamins, minerals and trace elements, which act as cofactors in many metabolic pathways and are essential for the integrity and proper functioning of the immune system. Unsurprisingly, numerous scientific studies have identified three key “guardians” of immune health: zinc, vitamin C and vitamin D.
Zinc is now well recognized as an essential element that influences growth and plays a crucial role in the development and integrity of the immune system. The proper function of immune cells depends heavily on zinc, affecting everything from skin barrier integrity to gene regulation in lymphocytes.
The second guardian is one we have known since childhood through orange juice. What was once considered a myth is now supported by strong evidence in both the prevention and treatment of infections. Vitamin C contributes to barrier integrity and wound healing, the formation and function of white blood cells, phagocytosis and microbial destruction, among other processes.
The third guardian—growing in popularity while becoming increasingly scarce in our bodies—is vitamin D, also known as the “sunshine vitamin.” This vitamin is essential for many biological processes and appears to play a more important role than previously thought. Since 2020, more than 1,000 scientific studies have been published on vitamin D, its effects on the immune system, and its relationship with infection risk and hospitalization outcomes following SARS-CoV-2 infection. The conclusions are remarkably consistent: low vitamin D levels are associated with poorer outcomes in cases of COVID-19 infection. Vitamin D has also been shown to reduce common cold symptoms, enhance adaptive immunity, and increase the expression of antioxidant-related genes.
The required amount of each micronutrient varies depending on sex, age, biochemical biomarkers and even genetic markers. Certain genetic variations can increase individual micronutrient requirements. Therefore, having access to this information can help you determine the amounts your body truly needs and maintain an optimal immune system.
If the pandemic has taught us anything, it is that our most valuable asset is our health.
