Aging impairs the body’s ability to fight infection due to chronic low-grade inflammation and a decrease in antibody-producing T cells. Consequently, 80 percent of deaths due to COVID-19 in the United States have been among adults 65 years of age and older. Researchers investigated the use of a ketogenic diet in mice as a strategy for treating COVID-19.

A ketogenic diet is a high fat, low carbohydrate diet. Adherence to a ketogenic diet reduces blood glucose levels, which are associated with increased inflammation. Adopting a ketogenic diet may be an effective strategy for limiting excessive inflammation, especially in older adults, who are more likely to have poor blood glucose control.

The SARS-CoV-2 virus, the cause of COVID-19 illness, induces lung inflammation. In severe cases, patients may need mechanical ventilation to breathe and may have long-lasting respiratory problems after recovery. Previous COVID-19 research has shown that white blood cells such as neutrophils and monocytes accumulate in the lungs. There they become more reliant on glucose, accelerate their mitochondrial metabolism, and produce more damaging oxidative compounds, contributing to unchecked inflammation and disease severity.

The researchers used mice that express the human angiotensin-converting enzyme (ACE) 2 receptor, which is the point of entry for the SARS-CoV-2 virus in the lungs and other organs. They fed young adult mice and older adult mice either a standard diet or a ketogenic diet for five days before exposing them to a hepatitis virus that closely mimics the SARS-CoV-2 infection in humans. The mice continued their assigned diet for an additional seven days following infection. The investigators measured markers of inflammation and metabolic function.

Older mice had significantly higher levels of inflammation and metabolic dysfunction at the beginning of the study. Upon infection, they had greater inflammation in the heart, adipose tissue, and hypothalamus; worse pneumonia symptoms and increased blood clot formation; and were more likely to die due to infection, compared to younger mice. The increased inflammation was due to an increase in neutrophil accumulation and a decrease in tissue-protective T cells in the lungs. A ketogenic diet reprogrammed metabolism and the immune system to a greater extent in older mice by increasing the number of beneficial T cells and reducing the number of harmful monocytes in the lungs, leading to less inflammation overall and reduced disease severity.

Although this study was conducted in mice, the authors concluded that a ketogenic diet may be a potential treatment for SARS-CoV-2 infection in older adults due to its ability to modulate immune function and dampen excessive inflammation.

• Link to full report.
• Learn more about COVID-19 and how vitamin D may reduce inflammation and disease severity from Dr. Roger Seheult.