What is the ketogenic diet?
The ketogenic diet is a low-carbohydrate and high-fat diet.
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It limits glucose availability, leading to switching to fatty acid metabolism. In the ketogenic diet, meals usually consist of a variety of poultry, fish, meat, and non-starchy vegetables.
This diet is associated with weight loss and improved metabolic health in people with obesity, reducing inflammation.
The ketogenic diet may protect against flu
In November 2019, a pioneering study published in Science Immunology Journal reported that feeding mice a high-fat, low-carbohydrate diet provides protection against the lethal influenza infection.
The ketogenic diet promoted the expansion of gamma delta T (γδ T) cells in the airways. These γδ T cells produce mucus in the linings of the lungs, which aids the body to get rid of infectious agents. Hence, researchers suggested that γδ T cells support barrier function in the lungs by changing the differentiation and function of the airway epithelial cells.
Researchers also found that the ketogenic diet blocked the formation of inflammasomes, which can cause deleterious immune system responses.
In this study, survival rates of mice fed a ketogenic diet were much higher than those fed a diet high in carbohydrates. Although this type of research is in its infancy, it shows some promising results of a ketogenic diet in combatting the flu virus.
The ketogenic diet enhances immunity against malignant glioma
In May 2016, a novel study published in BMC Cancer Journal found that the ketogenic diet enhanced immunity in a mouse model of malignant glioma.
Researchers found that mice fed with the ketogenic diet had increased tumor-reactive innate and adaptive immune responses, including increased cytokine production and cytolysis via tumor-reactive CD8+ T cells.
Mice maintained on the ketogenic diet had increased CD4 T cells infiltration, while T regulatory cell numbers stayed consistent.
A significant reduction in immune inhibitory receptor expression and decreased inhibitory ligand expression on glioma cells were seen in mice fed the ketogenic diet.
These findings of this study suggest that a ketogenic diet may function in part as an immune adjuvant, enhancing tumor-reactive immune responses in the microenvironment by mitigating immune suppression.
Ketogenic diet reverses maternal immune activation
In February 2017, an unprecedented study published in PLOS One journal found that a ketogenic diet improves behaviors in a maternal immune activation model of autism spectrum disorder (ASD).
In children, ASD incidence is influenced by prenatal factors such as maternal immune activation (MIA), which may occur due to viral or bacterial infection during the first trimesters.
In this study, pregnant mice were injected with the viral mimic polyinosinic-polycytidylic acid to produce MIA.
After weaning, offspring were fed a ketogenic diet or control diet for three weeks. Consistent with the higher incidence of ASD phenotype in males, control diet-fed MIA male offspring were not social and exhibited high levels of repetitive self-directed behaviors, whereas female offspring were unaffected.
However, ketogenic diet feeding partially or completely reversed all MIA-induced behavioral abnormalities in males, without any effect on behavior in females.
The findings of this study suggest that the ketogenic diet can be applied as a treatment for ASD symptoms via reversing all MIA-induced behavioral abnormalities.
Ketogenic diet positively affects immune cells
In January 2020, a very recent study published in Nature Reviews Endocrinology revealed that ketogenic diet feeding for 1 week in mice is a key mechanism that lessens inflammation and enhances metabolic outcomes.
Researchers fed mice a normal chow diet (calories were 58% carbohydrates, 24% protein, and 18% fat) or a ketogenic diet (calories were 0.1% carbohydrates, 10.4% protein, and 89.5% fat) for 1 week.
They found that the number of γδ T cells increased following a ketogenic diet. Further analyses revealed that the γδ T cells were metabolically protective.
In summary, the ketogenic diet may improve autistic behavior, positively affect immune cells, and provide protection against flu and the malignant glioma.
A ketogenic diet has plenty of research-based evidence that proves its immunity benefits.
Sources
- 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).
- Greenhill, C. (2020). Ketogenic diet affects immune cells in mice. Nature Reviews Endocrinology, 1-1.
- Lussier, D. M., Woolf, E. C., Johnson, J. L., Brooks, K. S., Blattman, J. N., & Scheck, A. C. (2016). Enhanced immunity in a mouse model of malignant glioma is mediated by a therapeutic ketogenic diet. BMC Cancer, 16(1), 310.
- Ruskin, D. N., Murphy, M. I., Slade, S. L., & Masino, S. A. (2017). Ketogenic diet improves behaviors in a maternal immune activation model of autism spectrum disorder. PloS one, 12(2).
Further Reading
A New Understanding of the Effects of Fever on Immune Cells