One of the health parameters your physician probably checks each time you visit is your cholesterol level. Your low-density lipoprotein and high-density lipoprotein levels provide information about your cardiovascular health, because high levels of LDL can indicate a greater risk for cardiovascular disease. This is because LDL cholesterol can build up in the arteries over time.
Significance
LDL is a type of cholesterol transporter. Technically, LDL is made up of a lipid, meaning fatty, and protein membrane, and is filled with cholesterol. LDL carries cholesterol through the bloodstream, making the cholesterol available to the body cells. Your physician monitors your LDL level because the American Heart Association has found that high levels of LDL in the blood indicate greater risk for cardiovascular disease.
Misconceptions
Many people call LDL "bad cholesterol," but it's actually not a type of cholesterol at all, explain Reginald Garrett, Ph.D., and Charles Grisham, Ph.D., in their book "Biochemistry." LDL is a type of cholesterol transporter -- specifically, it carries ingested cholesterol from the liver to the body cells. By contrast, what is commonly called "good cholesterol" is actually HDL. HDL is also a cholesterol transporter, and carries cholesterol to the liver for excretion.
Function
The body cells need cholesterol, even though high levels of cholesterol can be damaging to your cardiovascular health. That's why the liver packages dietary cholesterol into LDL and sends it out to the body cells. Cells take up cholesterol to maintain the rigidity of cell membranes, explain Mary Campbell, Ph.D., and Shawn Farrell, Ph.D., in their book "Biochemistry." Cells also use cholesterol to make vitamin D and a variety of hormones.
Considerations
When body cells have enough cholesterol, they stop taking up LDL from the bloodstream. As a result, LDL can accumulate in the blood -- particularly if you're eating a high-cholesterol diet or a diet high in saturated and trans fat. This causes cholesterol to begin to accumulate on the insides of artery walls, notes. Lauralee Sherwood, Ph.D., in her book "Human Physiology." The accumulated cholesterol forms arterial plaques, and narrows the arteries.
Expert Insight
To prevent buildup of cholesterol plaques on artery walls, the AHA recommends keeping LDL cholesterol levels as low as possible -- ideally below 100mg/dL. Diets low in saturated and trans fat typically result in lower cholesterol levels than diets higher in these LDL-raising fats. Unsaturated fat isn't associated with an increase in LDL, so plant-based fats, which are generally unsaturated, are much heart-healthier than animal or processed fats.
References
- American Heart Association: Cholesterol
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- "Biochemistry"; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
