Can a keto diet help fight the flu?

The ketogenic diet has gained popularity for its weight loss results, and new research indicates that it may also be helpful in fighting the flu.

In a study published in Science Immunology, researchers at Yale University found that specific diet changes may be effective in helping to fight influenza A infections.

“We found that mice on ketogenic diet were protected from flu because they were able to fortify the airway barrier better. This required a special type of lymphocytes known as gamma delta T cells,” said Akiko Iwasaki, PhD, principal investigator at the Iwasaki Lab at the Yale School of Medicine, Waldemar Von Zedwitz professor of Immunobiology and Molecular, Cellular and Developmental Biology, professor of Molecular Cellular and Developmental Biology, investigator at the Howard Hughes Medical Institute, and co-author of the study. “The keto diet expanded gamma delta T cells, and these cells modified the airway epithelial cells to secrete more mucus, which can trap the virus and protect the host from further spread.”

The discovery was accidental, according to the research team. The study was completed after researchers working on another project found that a ketogenic diet blocked the formation of immune system activators called inflammasomes, which can result in harmful immune responses. That discovery made researchers wonder what other immune responses might be impacted by the popular keto diet.

Immune responses are key to fighting infections, and for this project, mice in the study group were fed high-fat, low-carbohydrate ketogenic diets, while mice in the control group were fed high carbohydrate diets. The mice in the ketogenic group were found to have an expansion of gamma delta T cells in the lung, which improved barrier function against the flu.

In other words, the ketogenic diet was believed to activate certain immune cells that were previously not associated with the immune response to the flu, according to the research team. This response resulted in increased mucous production within the airway, which can help to trap the flu virus. Additionally, the research team found that when mice bred without coding for gamma delta T cells, a ketogenic diet offered no protection against influenza A.

Iwasaki said the studies have only been in mice so far, and additional research is needed to see if similar pathways would be activated in humans. There have also been criticisms of the ketogenic diet, which historically has been used as a medical diet under the watch of a physician because of the risks it includes. Iwasaki said there are no plans yet to make any clinical recommendations in relation to the team’s discovery.

“We first need to know whether people on ketogenic diet have similar changes in the lung,” she said. “Without such data, it is not possible to recommend any changes in clinical practice.”