A study, published in the Archives of Internal Medicine in 2004 has found that high total cholesterol levels can double an individuals remaining lifetime risk of developing coronary heart disease.

The researchers used data from the Framingham Heart Study (FHS) to determine how total cholesterol levels influence overall heart disease risk. More than 7,000 men and women were studied of which 1,120 developed coronary heart disease during the 25 year study period.

The researchers calculated that at the age of 40, men in the highest group for total cholesterol (greater than 240mg/dL) had a 57% probability of developing coronary heart disease by age 80. In contrast, men in the lowest group for total cholesterol (less than 200mg/dL) had a 31% probability of developing coronary heart disease. In women, the risks of developing coronary heart disease by age 80 were 33% and 15% for the high and low cholesterol groups respectively.

The full results of the study are presented in the graph below.

The American Heart Association (AHA) recommends individuals maintain a total cholesterol level below 200mg/dL. Total cholesterol is made up of two components: LDL and HDL. LDL makes up the larger proportion of of total cholesterol and is the type that is detrimental to heart health. An LDL cholesterol level of 100mg/dL or lower is considered optimal however further reductions in heart disease risk are seen at levels as low as 60mg/dL. HDL cholesterol is the other component of total cholesterol and is considered to be beneficial to heart health. It is recommended that an individual aims for a HDL to total cholesterol ratio of 5:1 with a ratio lower than 3.5:1 considered ideal.

The percentage of Americans with high cholesterol is currently decreasing with just 16% of men and 18% of women having total cholesterol levels greater than 240mg/dL. In 1975 the numbers were 26% and 28% for men and women respectively.

Despite these reductions in total cholesterol, heart disease remains the most common health problem facing the western world. In the United States, 49% of men and 32% of women will develop heart disease during their lifetimes. By comparison, cancer carries a 44% and 37% lifetime risk for men and women respectively, diabetes carries a 33% and 39% lifetime risk for men and women, while the lifetime risks for Alzheimer’s disease are 7% for men and 13% for women.