Cholesterol is a fat-like substance found in the blood. It is a key component of cell membranes and is a precursor of hormones and digestive juices. Cholesterol is derived from two sources:

  • your liver, which produces approximately 80% of blood cholesterol;
  • your diet, which contributes about 20% of blood cholesterol

Dietary factors such as excess fat, excess calories and excess cholesterol may have an effect on your blood cholesterol.

Cholesterol travels in the blood in combination with protein in the form of a lipoprotein. High density lipoproteins (HDL) are known as "good cholesterol" because they carry cholesterol away from cells and arteries. "Bad cholesterol" is found in low density lipoproteins (LDL). LDL carries cholesterol from the liver to the cells. An excess of LDL may result in deposits in artery walls, which build up and restrict blood flow. If an artery leading to the heart becomes blocked, a heart attack will result. If an artery in the brain is clogged, a stroke will result.

Blood Cholesterol guidelines and risk category evaluation have been established by panels of experts. A high blood cholesterol level is associated with an increased risk of heart disease. More specifically, increased levels of LDL cholesterol and reduced levels of HDL cholesterol have been linked with increased risk of coronary heart disease.

Current theories have identified a number of dietary and lifestyle factors that may influence the amount and type of cholesterol your body produces:

  1. Heredity – the primary factor determining your blood cholesterol level is genetics.
  2. Diet – the fat you consume has the greatest lowering effect on your blood cholesterol level. The typical Canadian diet derives approximately 40% of its calories from fat. Health
  3. Professionals recommend reducing total fat intake to about 30% of calories.
  4. Exercise – regular aerobic exercise may increase the amount of good cholesterol (HDL) in your blood, reduce the bad (LDL) and the triglycerides.
  5. Obesity – overweight individuals typically have low levels of good cholesterol (HDL), which is associated with an increased risk of heart disease. Weight loss can lead to an increase in HDL.
  6. Age and Sex – cholesterol levels typically rise with age. Women have lower incidence of heart disease before menopause, and this is associated with a higher HDL level than men.
  7. Smoking – smoking tends to lower good cholesterol levels and is a major contributor to cardiovascular disease.