HDL (high-density lipoprotein) has long held the reputation of being “good cholesterol”. HDL’s role is to pick up LDL (low-density lipoprotein, known as “bad cholesterol”) from cells, blood stream and blood vessels and bring it to the liver. The liver then breaks down the LDL into bile acids and salts so it could become excreted in the gut.
Now LDL is necessary because the body needs cholesterol, just not high amounts. The purpose of LDL is to transport cholesterol made in the liver to the cells. High LDL levels, however, are associated with atherosclerosis (plaque deposits along the blood vessels) which in turn increases risk of heart disease, stroke and dementia. High HDL levels appear protective, as the more HDL present, the less LDL remains in its dangerous form.
And HDL has an additional benefit…..it lowers inflammation. In a complex system, researchers believe the HDL down-regulates a factor that causes inflammation, hence HDL becomes an anti-inflammatory agent…. a hero in a delicate cardiovascular system.
However, this week, a study published in Cell Metabolism finds the HDL may worsen inflammation. Researchers found high levels of inflammation through macrophages (immune cells that help fight infection) in mice with high levels of HDL. Although the exact mechanism is unclear, the analogy we may be looking at is: the broom is sweeping away the dirt may be leaving a dust cloud.
Now personally, I have never in my 16 years of practice seen a patient with high HDL (greater than 60 mg/dl) suffer heart disease, so I still think its a “hero”. But more needs to be investigated to clarify if it poses risks.
Daliah Wachs, MD, FAAFP is a nationally syndicated radio personality on GCN Network and Board Certified Family Physician