Picture this: Due to the coronavirus outbreak, your county announces a shelter-in-place order starting at midnight tonight. All residents will be banned from leaving their homes except for essential work, food or services. You rush to the local grocery store to wipe the shelves of everything in sight: boxed pastas, cereals, chips, candy, cookies and sodas. Your pantry is now stocked with non-perishables to get you through this uncertain time.
However, health professionals don’t necessarily approve. The strong link between nutrition and immunity suggests that this survival strategy needs to be reevaluated.
Several research studies have discovered a correlation between high blood sugar levels and immune dysfunction. High blood sugar prevents critical immune cells called neutrophils from releasing disease-fighting proteins and enzymes stored within the cells. It also inhibits “phagocytosis,” a process where immune cells engulf foreign pathogenic particles that dare to cross their paths. Neutrophil and phagocytosis are key for human health, as they allow the body to fight various infections, including respiratory viruses.
High blood sugar is especially impactful when dealing with respiratory illnesses like COVID-19. This infectious disease can induce fever, cough, shortness of breath, pneumonia and death, in some cases. In animal models, high blood sugar was associated with altered lung structures, like increased permeability and collapsed tissue. This is harmful because it makes it difficult to breathe, store air in our lungs and eventually ensure oxygen is delivered to our muscles. Researchers also found that mice with Type 2 diabetes had issues recruiting immune cells to their lungs to fight off pathogens, increasing their susceptibility to influenza.
“Diabetes, particularly when poorly-controlled, is a clear risk factor for infections across the board,” said Sudeb Dalai M.S. ’10 M.D. ’13, an infectious disease specialist and clinical assistant professor at the Stanford School of Medicine and Palo Alto Medical Foundation.
Dalai is currently caring for hospitalized COVID-19 patients. In those with diabetes, he said, “we see much higher rates of skin, joint, bloodstream, urinary tract and respiratory infections including pneumonia. It’s particularly concerning in the current pandemic because they experience much higher rates of complications, respiratory failure and death.”
Along with diabetes, obesity is also a significant risk factor for delayed antiviral responses, which can enable the development of more severe illness within the body.
Previous chronic metabolic conditions also increase the risk of experiencing more severe symptoms of COVID-19. Bloomberg reports, “More than 99% of Italy’s coronavirus fatalities were people who suffered from previous medical conditions, according to a study by the country’s national health authority.” Three quarters of those who died had high blood pressure, 35% had diabetes and 33% had heart disease. These conditions can be improved by lifestyle changes and are exacerbated by poor dietary choices, including foods filled with sugars and simple carbohydrates.
In addition to affecting physical health, processed foods may also be detrimental to mental health — particularly during the vulnerable time of a fear-inducing pandemic.
Shebani Sethi, director of metabolic psychiatry at the Stanford School of Medicine and Silicon Valley Metabolic Psychiatry, said the complex interplay between food and mental and metabolic health led her to create the subfield, metabolic psychiatry, which focuses on treatment of metabolic dysfunction and investigates the influences of nutrition, inflammation and insulin resistance on psychiatric outcomes.
“People are really doing a disservice to their health if they are stocking up on ultra-processed junk food and sugar,” Sethi said. “It increases inflammation, disregulates the immune system, affects the brain and worsens mental health.”
Instead, she said, the focus should be on real whole foods, which would be better for both mental and physical health.
“We know the data out of Italy shows that most of those with severe disease also suffered from chronic conditions,” she added. “So if purchasing these items can be avoided, why add more risk?”
Contact Anika Sinha at anika100 ‘at’ stanford.edu.