Do you ever wonder why some people always tend to get sick but others who are exposed to the same virus or bacteria can successfully ward off illness? Exposure to a microbe isn’t always a guaranteed illness. Why? It boils down to the health of the host.

Individuals who can successfully ward off illness generally have a healthy terrain. Western medicine has focused on “germ theory” as the cause of illness- bacteria or viruses are the problem and the focus is killing them. Alternatively, “terrain theory” focuses more on the health of the host. It suggests that it is the internal strength or balance of an individual that protects or fails to protect him/her from illness.

Cold and flu season is upon us. Here are some ways to build a healthy terrain and thus support your body’s internal defenses:

1. Build a healthy microbiome. In addition to taking probiotics and eating fermented foods, eat a VARIETY of plants. A 2018 study found that the single most predictive factor of a healthy microbiome is eating a variety of plants. Researchers found that people who ate more than 30 different plant foods each week had a more diverse gut microbiome compared with those who ate 10 or fewer. Simply put, a diverse gut microbiome are the “good” bacteria that will defend your body from the pathogenic or “bad” bacteria. Dysbiosis (or an imbalance of gut bacteria) can be due to a diet low in fiber or a lack of plant diversity, a diet high in sugar, antibiotic use, and stress. Dysbiosis is associated with a greater incidence of pro-inflammatory cytokine storm and worsened outcomes of viral infections.
2. Get enough sleep. One of the most important factors in improving immune resilience against respiratory infections is to ensure you are getting adequate, quality sleep. Low concentrations of melatonin can impair sleep as well as impact immunity. In addition to melatonin’s ability to enhance sleep quality, melatonin’s antioxidant and anti-inflammatory effects also play a role in optimizing immune function. Recent research showed that mice exposed to RSV (respiratory syncytial virus) were protected against RSV-induced inflammatory lung damage. Melatonin decreased oxidative stress and the production of pro-inflammatory cytokines. Aim for 8-9 hours of sleep per night and consider taking 2-5 mg melatonin approx. 60 minutes prior to bedtime.
3. Exercise. This study of 1000 people published in the British Medical Journal revealed that the most significant factor for prevention of respiratory infections, even over stress and diet, was exercise. Physical activity, for five or more days per week, was associated with a 43% reduced risk of upper respiratory infection and also severity of infection, compared to exercising less than one day each week. Even just 20 minutes per day is better than nothing!
4. Ensure optimal nutrient status. These are the most important nutrients for respiratory and overall immune health:

• Zinc– Immune cells are dependent on zinc for their development and maintenance. Zinc has been shown to reduce the duration of the common cold. Zinc rich food sources include pumpkin seeds, legumes, and oysters. Zinc picolinate is the best form of supplemental zinc. Vitamin A– Vitamin A is involved in the function of immune cells such as neutrophils, natural killer cells, monocytes, and T and B lymphocytes. A rich dietary source of vitamin A is liver. Other sources are foods rich in beta-carotene, such as green leafy vegetables (spinach!), carrots and cantaloupe. Your body converts beta-carotene into vitamin A.
• Vitamin D– Vitamin D is critical for proper upper respiratory function. A large meta analysis concluded that individuals taking a regular vitamin D supplement had a lower likelihood of developing acute respiratory tract infections. Vitamin D may also reduce the risk of pro-inflammatory cytokine storms that are associated with worse outcomes of many viral infections. Ask your doctor to test your vitamin D to help determine the best dose for you. Goal level is between 60-80.
• Vitamin C– Vitamin C can shorten the duration of respiratory tract infections. It also is associated with a significant reduction (45-91% reduction) in the incidence of the common cold. Vitamin C rich food sources include citrus, broccoli, bell peppers, and kiwis.

I hope you feel empowered with the above information to build a healthy terrain and hopefully prevent viral infections this winter. If you do get sick, optimizing the above factors will most likely improve your outcomes…because the health of the host matters!

Editor’s Note: The information in this article is intended for your educational use only. Always seek the advice of your physician or other qualified health practitioners with any questions you may have regarding a medical condition and before undertaking any diet, supplement, fitness, or other health program.