Researchers highlight flu-fighting potential of keto diet but flag need for human studies

19 Nov 2019 --- A ketogenic diet helps to enhance production from airway cells that can effectively trap the influenza virus. This is according to a Yale University study, which found that influenza-infected mice fed on ketogenic food had a higher survival rate than mice fed food high in carbohydrates. The diet of meat, fish, poultry and non-starchy vegetables triggered the release of gamma delta T cells in the lungs that influence mucus production in the cell linings of the lung. This subset of cells was not previously associated with the immune system’s response to influenza.

“There were lots of twists and turns in this study. It took us a long time to find how the keto diet protected mice from influenza disease. We assumed it would be a more conventional mode of protection, such as the well-known type I interferon antiviral pathway. However, it turned out to be totally different,” co-senior author Akiko Iwasaki, the Waldemar Von Zedtwitz Professor of Immunobiology and Molecular, Cellular and Developmental Biology, and an investigator of the Howard Hughes Medical Institute, tells NutritionInsight.

The research project, now published in the journal Science Immunology, was the brainchild of two trainees. Working in the lab of co-senior author Visha Deep Dixit, the Waldemar Von Zedtwitz Professor of Comparative Medicine and of Immunobiology, Emily Goldberg had seen how the ketogenic diet blocked the formation of immune system activators called inflammasomes. 

Meanwhile, Ryan Molony worked in Iwasaki’s lab, which had found that inflammasomes can cause harmful immune system responses in their host. The trainees then wondered if diet could affect the immune system response to pathogens such as the flu virus.

When mice were bred without the gene that codes for gamma delta T cells, the ketogenic diet provided no protection against the influenza virus. “This study shows that the way the body burns fat to produce ketone bodies from the food we eat can fuel the immune system to fight flu infection,” says Dixit.

The ketogenic diet is increasingly popular as people’s recognition of fat as a healthy and crucial dietary component grows.This finding was totally unexpected, according to Iwasaki, who notes that she was surprised to discover the role of gamma delta T cells in coordinating the beneficial effects of a ketogenic diet.

However, she warns that it is still too early to predict the impact of the keto diet in humans. “We now need to test the impact of keto diet on human respiratory infections to know whether our findings in rodents hold true in humans.” 

The ketogenic diet is increasingly popular as people’s recognition of fat as a healthy and crucial dietary component grows. Earlier this year, a high-fat, low-carbohydrate diet – similar to a keto or Atkins diet – was found to potentially improve brain function and memory in older adults. Separate research also found that a keto diet is the optimal way to combat obesity in the military and promote soldiers’ fitness levels.  

This has led to rampant NPD in the keto-friendly space, with Unbun Foods aiming to disrupt the bakery category with its grain-free offerings. Unbun’s products are touted as offering a healthy, low-carb alternative to lettuce buns or traditional chemical-laden gluten-free buns.

Meanwhile, US-based start-up Zeno Nutrition launched its diabetic- and keto-friendly bars in three new flavors earlier this year. ZenoBars are marketed as being the first vegan energy bars specifically targeting individuals with low-glucose goals. 

By Katherine Durrell

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