Extreme levels of HDL associated with increased risk of infectious disease

Both high and low concentrations of HDL cholesterol are associated with higher risks of infectious disease including gastroenteritis and pneumonia, according to new research published April 7 in the European Heart Journal.

Researchers analyzed more than 100,000 individuals from the Copenhagen General Population Study and the Copenhagen City Heart Study and followed them for six years. Measurements of HDL cholesterol were taken at the beginning of the study.

“Low and high HDL cholesterol concentrations found in 21 percent and 8 percent of individuals were associated with higher risk of infectious disease in the general population,” wrote Børge Nordestgaard, professor and chief physician at the University of Copenhagen and Copenhagen University Hospital in Denmark. “These findings do not necessarily indicate causality.”

Additionally, individuals from the study cohort with low HDL cholesterol levels had a 75 percent increased risk of infectious disease, compared to the control group. The risk of infectious disease was 43 percent higher in people with very high HDL cholesterol.

“Numerous studies in animals and cells indicate that HDL is of importance for the function of the immune system and thereby the susceptibility to infectious disease, but this study is the first to examine if HDL is associated with the risk of infectious disease among individuals from the general population,” said co-author and physician Christian Medom Madsen, PhD.

The authors noted no direct cause and effect connection between very low or very high levels of HDL cholesterol and an increased risk of infectious disease. However, due to the genetic component of the study, they also added they “cannot rule out” a causal relationship.

“Our findings indicate that, in the future, research into the role and function of HDL should not narrowly focus on cardiovascular disease, but rather focus on the role of HDL in other disease areas, such as infectious disease,” the authors concluded.