The flu season is abruptly coming with the beginning of Spring. The best way to prevent influenza infection is by preserving our immune system’s health. The immune system can be boosted through proper nutrition that focuses on lowering inflammation and oxidative stress (1). Vitamins can play a critical role in facilitating this nutritional fortification.
It’s a Gut Feeling
The gut microbiome helps the immune system thrive. It is the core of our bodily health, preventing inflammation and disease through short-chain fatty acids (SCAA’s). Millions of bacterial organisms collectively act in the gut, filtering out the bad from the good. Since the gut microbiome constitutes 70% of our immune system (2), it should be a priority. How do we nourish it optimally?
Prebiotics & Probiotics
Fiber is a powerhouse nutrient that can inhibit viral replication. It’s a prebiotic, meaning it produces the SCAA’s that populate and fuel the microbiome. Also, they contain phytochemicals such as polyphenols and carotenoids that promote anti-inflammatory bacteria. It’s been shown for the past decade that fiber is critical in fighting off influenza. Fruits, vegetables, nuts, legumes, and whole grains round out the long list of prebiotic foods.
If prebiotics create bacteria, probiotics maintain their communal health. Probiotics reduce respiratory infections by defending the immune system’s lines of defense (3). It was shown to be especially effective in protecting the lungs against influenza. Fat-free yogurt, sourdough, apple cider vinegar, kefir, and miso are strong probiotic choices.
Omega-3 fatty acids contain polyunsaturated fats, adding diversity to gut microbes (4). Gut diversity leads to anti-inflammatory reactions against viruses. Omega-3’s also oxygenate metabolites, alleviating oxidative stress. Fish and seafood are the most popular omega-3 sources, but they can also be found in healthy fats such as seeds, avocados, and edamame.
Vitamin A produces healthy mucus in the respiratory system and intestines, protecting the microbiome. Many countries that culturally have low-meat intakes are deficient in vitamin A and iron. Fortunately, meatless foods, such as sweet potatoes, carrots, and leafy greens, also contain great sources of vitamin A.
Vitamin C manages the severity of illnesses along with supporting respiratory function. Viral infections tend to target vitamin C in our bodies, something we do not independently produce. It’s crucial to keep vitamin C levels higher in times of illness. The foods that contain the most vitamin C are either fruits or vegetables, which are also great prebiotics. Such foods include oranges, bell peppers, lemon, and broccoli.
Vitamin D has been a vitamin of interest since the start of the COVID-19 pandemic. It supports overall health in our bones, muscles, skin, and gut, alongside improving mental health. The winter season prevents people from absorbing vitamin D from the sun. With half of the planet’s population already considered as vitamin D deficient, it’s an even more important nutrient to improve.
Its role in fighting off viral infections includes the management of cytokines. These cause the spread of a virus, and vitamin D counters pro-inflammatory cytokines with anti-inflammatory ones. Studies in the past two years focusing on vitamin D’s impact on influenza and COVID-19 have increasingly demonstrated these findings (5) (6). It is not the Holy Grail key to autoimmunity, yet it should not be ignored for overall health improvement.
Despite being a mineral and not a vitamin, zinc still contains anti-viral characteristics. It supports the cell-barrier function, especially in the lungs. It also reduces a virus’s impact on protein synthesis. When a virus attacks protein molecules, zinc joins vitamin D on the line of defense. Zinc deficiency can cause immune cell dysfunction (6). High-protein animal sources like oysters and red meat contain zinc. Fiber-rich foods like tofu, seeds, legumes, and oatmeal also contain zinc, but have less than the animal sources.
The gut microbiome goes through a new regeneration every fifteen minutes. It is never too late to properly feed your gut and improve your immune system. Avoiding processed foods and added sugars should be emphasized. Meanwhile, a diet containing fibrous foods, healthy fats, and antioxidants will improve your immune system. Supplementation can round off the list of healthy choices, covering all remaining bases when it comes to maintaining sufficient vitamin levels.