A new study from researchers at Portland State University has reported that a diet high in saturated fats – such as the ketogenic or “keto” diet – can alter the immune system in mice.
Some fats have more impact than others
The keto diet is a popular example of a low-carbohydrate, high-fat diet that is used for weight loss. In their research, lead author Dr. Brooke Napier, assistant professor of biology, and colleagues illustrated that mice fed either a Western (high-fat, high-sugar) diet or a ketogenic diet were more susceptible to sepsis than mice fed a normal diet.
Saturated vs. unsaturated fats
Saturated fats are solid at room temperature and commonly found in animal products, such as meat and dairy. Unsaturated fats are liquid at room temperature and are mostly found in oils from plants and fish. Saturated fats are reputed to increase “bad” cholesterol which increases the risk of heart disease and stroke.
The researchers identified one saturated fat that was associated with an increased risk of sepsis when injected into mice fed a normal diet. This fat is palmitic acid, which exists in high proportions in meat and dairy products and can also be found in breast milk.
“It was just exposure to this one saturated fat that made them more susceptible to sepsis mortality,” said Napier. “The idea that you could have a specific fat in your diet that would cause such a drastic outcome in disease is kind of incredible.”
What is sepsis?
Sepsis is a life-threatening condition where an immune response to an infection goes into overdrive and damages the body’s own tissues and organs.
In the mice fed Western or ketogenic diets, and the mice injected with palmitic acid, levels of inflammatory cytokines in the blood increased, which can result in systemic inflammation and fever during sepsis, suggesting palmitic acid affects the immune system by causing inflammation.
However, palmitic acid also reprograms the innate immune system by triggering trained immunity. Trained immunity is the “learned” part of the innate immune response, where an incident of high inflammation alters stem cells in the bone marrow to enable increased production of inflammatory…