Cholesterol plays an important role in immunity, especially with bloodborne pathogens. One study here explained that total cholesterol (TC) fluctuates wildly during acute infections indicating cholesterol may have immune mediated activity. The article reviewed 19 cohort studies that revealed a correlation between increased death from respiratory and gastrointestinal diseases (both infectious) and low TC.
It also showed that people admitted to hospitals due to an infectious disease also had low cholesterol. Some common diseases noted were genitourinary infections, skin, and subcutaneous (just below the skin) infections. HIV and death from AIDS were also associated with lower cholesterol levels.
Patients with low TC suffering from chronic heart failure had a poorer prognosis after surgery and lower long-term survival rates. This also included patients recovering from abdominal surgeries. Another interesting note was that people suffering from hepatitis B including asymptomatic carriers also have lower TC levels.
Although the evidence shows that young and middle-aged men are at risk for heart disease with high cholesterol (this can be controlled through diet) their risk becomes negated when they get close to 50. As one gets older, higher cholesterol is associated with longevity 1, 2 in both men and women. This may be due to not only the cardioprotective effects of higher cholesterol but also to innate immunoprotective mechanisms associated higher TC.
Interestingly, eating a diet lower in fiber increases serum cholesterol due to the gut’s increased ability to reabsorb cholesterol in the absence of fiber. In addition to this, diets higher in linoleic and linolenic acids (essential fatty acids) may help prevent or reverse atherosclerosis (yes, atherosclerosis can be reversed).
Another article showed that one cause of cardiovascular disease may result from bacterial communities reinfecting arterial walls. Suppressed immune response related to low cholesterol may be a contributing factor.
If you want to reduce your risk of infection and improve immunity response mechanisms, one thing to consider is maintaining healthy cholesterol levels. Cholesterol may also play a role in a number of autoimmune disorders.