Cholesterol is not a fat, it is a sterol. It is a waxy, fat-like substance present in all animals, including humans. Cholesterol is needed for many bodily functions and serves to insulate nerve fibers, maintain cell walls and produce vitamin D, various hormones and digestive juices. Cholesterol is produced by the liver. If you eat more dietary cholesterol, the liver produces less!

Elevated total and LDL cholesterol levels in the blood are associated with an increased risk of coronary heart disease (CHD). However, most people who get CHD have low cholesterol levels in their blood! A more likely candidate, with increasing support, for CHD are high homocysteine levels (above 8µmol/L) in the blood. It is commonly believed, but not proven, that dietary cholesterol affects the level of total and LDL cholesterol in the blood. This belief has led to a maximum recommended intake of dietary cholesterol of 300mg/day.

It has been demonstrated that saturated fat and trans-fatty acids in food, not cholesterol, influence blood cholesterol levels. The average response to a 100mg/day change in dietary cholesterol intake is a 2.5mg/dL change in blood cholesterol levels. While some individuals are more sensitive to the effects of dietary cholesterol (15-20% of the population), it can be estimated that reducing dietary cholesterol intake from 400mg/day to 300mg/day results in a blood cholesterol reduction of 3.2mg/dL in cholesterol sensitive individuals and as little as 1.6mg/dL in cholesterol insensitive individuals.

Cholesterol travels in the blood in distinct particles containing both lipid and proteins (lipoproteins). Cholesterol contains three major classes of lipoproteins: low density lipoproteins (LDL), high density lipoproteins (HDL), and very low density lipoproteins (VLDL). A brief overview and recommended healthy target level for each are presented below.

• Total Cholesterol high levels can cause narrowing or blockage of blood vessals which may lead to a heart attack or stroke. Low level may indicate liver problems. The recommended target level is: < 5.2
• LDL (low-density lipoprotein) is bad cholesterol and the major atherogenic lipoptotein and lowering LDL levels is the primary target for lowering the risk of CHD; it makes up 60-70% of total cholesterol in the blood. The recommended target level is: < 2.5
• HDL (high-density lipoprotein) is good cholesterol which helps move cholesterol back to the liver for removal from the bloodstream and higher HDL levels provides some protection against the development of atherosclerosis; it makes up 20-30% of total cholesterol in the blood. The recommended target level is: > 1.2
• VLDL (very low density lipoproteins) commonly called triglycerides, are triglyceride-rich lipoproteins which are produced by the liver and are precursors of LDL, some forms of VLDL, particularly VLDL remnants, appear to promote atherosclerosis, similar to LDL. VLDL provides a major reserve of energy for the body, high level associated with heart disease; can be reduced by losing weight, eating less animal fat, eating more fish, and eating fewer carbohydrates. It makes up 10-15% of total cholesterol in the blood. The recommended target level is: < 2.0
• Total Cholesterol/HDL ratio is an important predictor in determining risk of CHD. The recommended target level is: < 3.5

References...

1. National Cholesterol Education Program (NCEP) ATPIII Guidelines, September 2002
2. Plasma lipid and lipoprotein responses to dietary fat and cholesterol: a meta-analysis, WH Howell et al, AJCN, Vol. 65, 1747-1764, 1997.
3. Controlling Cholesterol the Natural Way, Kenneth H. Cooper, MD. Contains everything you need to know about controlling cholesterol. Buy it today! Dr. Cooper stresses the importance of controlling what we eat rather than taking drugs to control the effects of what we've eaten. In conjunction with proper diet and exercise, Dr. Cooper promotes the use of functional foods, or nutraceuticals, rather than pills, to control the excessive accumulation of cholesterol. Functional food examples: Benecol (plant stanols derived from "tall oil" wood pulp of pine trees; for example, McNeil spreads, salad dressings, and yogurt); Becel Pro.activ (margarine with plant sterols; not approved, as of October 6 2001, for use in Canada); Take Control (with plant sterols derived from soybeans; for example, Lipton spread); Phytrol (plant sterol-phytosterols-extracted from wood pulp; for example, Novatis food additive found in margarine, salid dressings, and mayonnaise; also see the Altus Foods joint venture with Quaker); Psyllium (grain-seed husk; for example, Kellogg's All Bran Buds).