The Functional Medicine Approach to COVID-19: Lifestyle Practices for Strengthening Host Defense

Published April 8, 20During a time of heightened potential infection from COVID-19, favorably modulating immune function can be an important strategy for not only reducing the chance of infection, but for potentially reducing the severity of and sequelae from infections. Since lifestyle factors have a large effect on immune function, when working with patients in the era of COVID-19, the modifiable lifestyle factors below are excellent first steps.

Food/Nutrition

Overall recommendations: Research indicates that plant-based foods such as those high in phytonutrients, water- and lipid-soluble vitamins, and other antioxidants, as well as dietary fiber, can help downregulate an overactive immune response.

Specific recommendations for patients:

1. Eat plenty of fruits and vegetables. Aim for 9-13 servings per day of a variety of types for a wide array of phytonutrients to enhance the gut microbiome.
2. Consume dietary fiber, a minimum of 28-35 grams daily, preferably from whole foods.
3. Eat fermented vegetables or other probiotic-containing foods to maintain epithelial health and gut barrier function.
4. Reduce or avoid immune offenders such as added sugars and salt, high-glycemic foods (including processed carbohydrates), and excessive saturated fat.

Food and nutrition are major daily input for health and well-being. There are three mechanisms that may be involved in the ability of food-derived compounds to reduce viral infection and severity:

1. Balancing inflammatory pathways.
2. Reducing oxidative stress and increasing antioxidant levels.
3. Harmonizing the gut microbiome.

Balancing inflammatory pathways

Inflammation and immune responses often occur together in a viral infection. While inflammation is required in the initial stages of an immune reaction to infection, prolonged release of inflammatory mediators (e.g., interleukins, prostaglandins, tumor necrosis factor-alpha [TNF-alpha]) may cause system-wide perturbations. Low-level chronic inflammation and activation of the innate immune response are suggested mechanisms for increased risk of lifestyle-induced diseases such as type 2 diabetes.^[1] Therefore, to lower inflammatory load, clinicians suggest refraining from eating a Westernized diet^[2] and shifting toward a balanced dietary pattern resembling the well-studied Mediterranean diet.^[3],[4],[5]

Furthermore, data from the Nurses’ Health Study suggests that an inflammatory dietary pattern has been identified as one that is high in “sugar-sweetened soft drinks, refined grains, diet soft drinks, and processed meat but low in wine, coffee, cruciferous vegetables, and yellow vegetables.”^[6] Therefore, reducing or omitting foods that negatively impact the inflammatory cascade—such as those containing added sugars,^[7] salt,^[8] or trans fats,^[9] as well as those that have a high glycemic index^[10] or excessive amounts of saturated fats^[11]—would be helpful in lessening the overall inflammatory burden. A systematic review has shown that a single, high-fat processed meal (e.g., a meal consisting of white bread, butter, cheese, and a milkshake) leads to increases in the inflammatory cytokine interleukin-6 (IL-6) of around 100% relative to baseline within six hours of eating.^[12] Given that a range of pesticides are also known to impact immune function, where financially feasible, increasing consumption of organically grown produce may lower the inflammatory burden and improve immune function.^[13]