Can going keto save you from the flu?

Influenza A virus infection is a world health concern. We as a country have issues with vaccine compliance that leads to a whole host of other issues such as decreased herd immunity and the recurrence of diseases that were thought to have been long gone. Additionally, the flu vaccine that we are encouraged to get can sometimes be a gamble. In January 2015, the CDC ran early estimates on the effectiveness of the flu vaccine for the previous 2014-15 flu season and found that the influenza A viruses were predominant and more than 2/3 of those viral strains circulating were genetically different than the A vaccine component for the 2014-15 seasonal flu vaccines. A study recently published, suggests that the ketogenic diet could help prevent against flu infection which could be highly beneficial to vulnerable populations that are unable to get vaccinated and must rely on herd immunity and even extra protection for those of us that get the vaccine but are just unlucky enough to get the flu anyways. 

The ketogenic diet may be more than just another fad-diet. In mid-November, a study was published looking at the effects that the ketogenic diet could have on the flu. Using mice as a model organism, the diet was found to prevent lethal influenza A infection by activating specific T cells in the lungs. These specific T cells were not originally thought to play a role in the respiratory system. However, after the mice metabolically adapted to the ketogenic diet, these T cells were activated and started triggering mucus production in the epithelial cells of the lungs helping create a barrier from infection.

In the study, mice were either given a ketogenic diet, carbohydrate diet, or given ketone bodies that would bypass the liver’s need to make ketones. Converting to a ketogenic diet forced the physiology of the mice to undergo an adaptation in their metabolism that resulted in enhanced antiviral resistance and survival through the expansion of γδ T cells in the lungs. These specific T cells began to play a role in the respiratory system by triggering mucus production in the epithelial cells of the lungs. This change was not seen in the other mice because they still had access to glucose for a fuel source so there was no need to undergo a full body adaptation to use ketones for fuel. The mice that did not metabolically adapt to the ketogenic diet did not experience the expansion of the γδ T cells and were not protected against infection by the lethal influenza A virus. The mice that did have changes to their T cells were observed to have increased antiviral resistance. The researchers then went on to confirm the importance of these T cells in protection by feeding mice without the presence of γδ T cells the ketogenic diet and observed they were not protected from the influenza A virus.

We really are what we eat and this study showed that the way food is broken down could really influence the immune system's ability to readily fight infections such as the flu. So as we enter flu season, get your flu shot, wash your hands, and don't feel so bad about adding a little extra butter to your meals.            

References:

Flannery, B., Clippard, J., Zimmerman, R. K., Nowalk, M. P., Jackson, M. L., Jackson, L. A., ... & Gaglani, M. (2015). Early estimates of seasonal influenza vaccine effectiveness—United States, January 2015. MMWR. Morbidity and mortality weekly report, 64(1), 10.

Goldberg, E. L., Molony, R. D., Kudo, E., Sidorov, S., Kong, Y., Dixit, V. D., & Iwasaki, A. (2019). Ketogenic diet activates protective γδ T cell responses against influenza virus infection. Science immunology, 4(41).

Yale University. (2019, November 15). Ketogenic diet helps tame flu virus. ScienceDaily. Retrieved December 6, 2019 from www.sciencedaily.com/releases/2019/11/191115190327.htm