Along with social distancing measures and effective vaccines, a healthy immune system is our best defense against coronavirus infection. To keep it that way, proper nutrition is an absolute must. Although not a replacement for medicine, good nutrition can work synergistically with medicine to improve vaccine effectiveness, reduce the prevalence of chronic disease and lower the burden on the health care system.
The impact of the Western diet
Scientists know that people with preexisting health conditions are at greater risk for severe COVID-19 infections. That includes those with diabetes, obesity, and kidney, lung or cardiovascular disease. Many of these conditions are linked to a dysfunctional immune system.
Patients with cardiovascular or metabolic disease have a delayed immune response, giving viral invaders a head start. When that happens, the body reacts with a more intense inflammatory response, and healthy tissues are damaged along with the virus. It’s not yet clear how much this damage factors into the increased mortality rate, but it is a factor.
What does this have to do with nutrition? The Western diet typically has a high proportion of red meat, saturated fat and what’s known as “bliss point foods” rich in sugar and salt. Adequate fruit and vegetable consumption is missing. Despite the abundance of calories that often accompanies the Western diet, many Americans don’t consume nearly enough of the essential nutrients our bodies need to function properly, including vitamins A, C and D, and the minerals iron and potassium. And that, at least in part, causes a dysfunctional immune system: too few vitamins and minerals, and too many empty calories.
A healthy immune system responds quickly to limit or prevent infection, but it also promptly “turns down the dial” to avoid damaging the cells of the body. Sugar disrupts this balance. A high proportion of refined sugar in the diet can cause chronic, low-grade inflammation in addition to diabetes and obesity. Essentially, that “dial” is never turned all the way off.
While inflammation is a natural part of the immune response, it can be harmful when it’s constantly active. Indeed, obesity is itself characterized by chronic, low-grade inflammation and a dysregulated immune response.
How nutrients help
Nutrients, essential substances that help us grow properly and remain healthy, help maintain the immune system. In contrast to the delayed responses associated with malnutrition, vitamin A fights against multiple infectious diseases, including measles. Along with vitamin D, it regulates the immune system and helps to prevent its overactivation. Vitamin C, an antioxidant, protects us from the injury caused by free radicals.
Polyphenols, a wide-ranging group of molecules found in all plants, also have anti-inflammatory properties. There’s plenty of evidence to show a diet rich in plant polyphenols can lower the risk of chronic conditions, like hypertension, insulin insensitivity and cardiovascular disease.
Why don’t we Americans eat more of these plant-based foods and fewer of the bliss-based foods? It’s complicated. People are swayed by advertising and influenced by hectic schedules. One starting place would be to teach people how to eat better from an early age. Nutrition education should be emphasized, from kindergarten through high school to medical schools.