Cholesterol has many important physiologic functions, including fat digestion and hormone synthesis. Because cholesterol does not dissolve in the blood, proteins such as LDL, or low-density lipoprotein, are used to transport through the body. If cholesterol levels rise, too much LDL builds up in the blood and can form clots, which can lead to heart attacks. Lower LDL levels reduce this risk, but the precise level at which greatest benefit is achieved is still unknown.
LDL Levels
An LDL cholesterol level of under 100 mg/dL is considered optimal. Values between 100 and 129 are near-optimal, 130-159 mg/dL is borderline high, 160-189 is high and 190 mg/dL and above are very high. According to the American Heart Association, a high level of LDL cholesterol (greater than 160 mg/dL) increases your risk of heart disease. If you have heart disease, you cholesterol should be below 100 mg/dL, maybe even 70 mg/dL or lower.
Heart Disease
There are many types of heart disease, which often culminate in heart failure, also known as congestive heart failure. In this condition, often due to a defect in contractility, the heart is unable to pump blood at a rate commensurate with the requirements of the tissues. The heart is one of the most metabolically active organs, depending on a constant influx of blood to meet its energy requirements. If this blood supply is compromised, as by a cholesterol-causing clot, heart damage results, manifesting as a heart attack.
Dietary Cholesterol
Typically the body makes all the cholesterol it needs, so you don't need to consume any. Plant foods do not contain cholesterol, and animal foods such as egg, meat, fish, chicken and dairy contain cholesterol to a greater or lesser degree. According to the USDA, cholesterol intake of approximately 250 mg per 1,000 calories is associated with an increased risk of congestive heart disease. One egg yolk contains 250 mg cholesterol.
Other Factors
In addition to diets high in cholesterol, high saturated fat intake increases LDL levels. Losing weight and increasing physical activity can lower LDL levels and decrease the severity and incidence of heart disease. Smoking and high blood pressure also are risk factors for heart disease, so in the presence of one or both of these, your target LDL level might be lower. Ask your doctor.
Recent Studies
Although LDL cholesterol levels below 100 mg/dL are considered protective against heart attacks even in patients with existing heart disease, new research shows as much as half of patients hospitalized for a heart attack had LDL levels in the optimal range. Therefore, according to Dr. Gregg Fonarow of UCLA Medical Center, current guidelines might not be low enough to cut heart attack risk in those with heart disease. Whether new guidelines would apply to the general population has not been determined. Additional research is needed.
