Cholesterol is a waxy substance, held by lipids, that the body produces in the liver and is also present in food. The body requires cholesterol to function properly, but the nutrient has a reputation for causing health difficulties. This is because excess cholesterol in the bloodstream can build up along arterial walls, causing cardiovascular difficulties and other health complications. However, this effect depends on the proportion of each type of cholesterol rather than its presence.
LDL
The actual culprit in severe health complications associated with high cholesterol is low-density lipoprotein -- LDL -- cholesterol. LDL cholesterol can cause atherosclerosis, which is buildup on artery walls. This condition can lead to hypertension, poor circulation, heart attack and stroke. LDL cholesterol is present in meats, but in the blood it is a combination of excess ingested cholesterol and excess cholesterol excreted by the liver in the form of very-low-density lipoprotein -- VLDL -- cholesterol. When LDL cholesterol is in the bloodstream in very high amounts, cells reject its absorption, resulting in LDL cholesterol molecules without receptors. The body initiates an immunological response against these free molecules that regular cells can no longer absorb, which results in their absorption by macrophages. These cells swell into foam cells that can attach to tissue as they navigate the circulatory system, resulting in atherosclerosis.
HDL
High-density lipoprotein -- HDL -- cholesterol, like other nutrients, is beneficial in high enough amounts. In fact, HDL cholesterol can lower LDL cholesterol levels. This is the source of its reputation as "good" cholesterol. HDL cholesterol in the bloodstream originates in the liver, which excretes it to transport free cholesterol in the bloodstream to tissues and organs throughout the body. HDL cholesterol has an inversely proportionate relationship with LDL cholesterol with regard to cardiovascular health. Regular physical activity, good nutrition and a healthy weight are the best ways to maintain high HDL cholesterol levels.
Low LDL and HDL Cholesterol
In accordance with its activity in the body, it is best to maintain low LDL cholesterol levels. The lower your blood LDL cholesterol levels, the lower your risk for cardiovascular complications like heart disease, stroke and heart attack. To avoid health difficulties optimally, keep daily consumption of LDL cholesterol under 100 mg per deciliter. On the other hand, extremely low LDL cholesterol, such as 50 mg per deciliter, could lead to complications like anxiety, depression, cancer, and preterm labor or low birth weight. In contrast, high LDL cholesterol levels evidence low HDL cholesterol levels, or a blood saturation of 40 mg per deciliter.
Considerations
Myriad factors contribute to dangerous conditions associated with cholesterol levels. For example, triglycerides, which are the most common type of fat present in the body, can contribute to cholesterol imbalances in favor of LDL cholesterol. Smoking, obesity, inactivity, alcoholism and stress can independently raise triglyceride and LDL cholesterol levels while reducing HDL cholesterol levels. Overall cholesterol saturation in the blood should not exceed 200 mg per deciliter. The vitamin niacin may raise HDL cholesterol levels, thereby reducing LDL cholesterol.
References
- MedlinePlus: Cholesterol
- MayoClinic.com: Niacin to Boost Your HDL, "Good," Cholesterol
- Harvard Medical School Family Health Guide: LDL Cholesterol: Low, Lower, and Lower Still
- MayoClinic.com: Can Your Total Cholesterol Level Be Too Low?
- "New England Journal of Medicine"; HDL Cholesterol, Very Low Levels of LDL Cholesterol, and Cardiovascular Events; P. Barter et al.; September 2007
- American Heart Association: What Your Cholesterol Levels Mean
