Cholesterol is made up of LDL and HDL. LDL cholesterol (the “bad cholesterol”) is deposited onto the walls of arteries, causing inflammation and atherosclerosis, and the end result is a heart attack or blockages in arteries of the neck or leg. HDL cholesterol (the” good cholesterol”) takes cholesterol away from the artery walls. Total cholesterol numbers can be misleading at times. If someone has an unusually high HDL cholesterol, that’s good, but it raises the total cholesterol. A high HDL can be due to genetics and can be raised by exercise. For those of you interested in formulas, total cholesterol = LDL + HDL + triglycerides/5 (but this is not valid if the triglyceride is over 300 mg.).
Normal cholesterol has changed over the years as more research was done. In 1974, normal was up to 250 mg. In the 1990’s, normal was reduced to a maximum of 200 mg. Normal LDL is below 100 mg. Normal HDL cholesterol is 40 mg. or greater. A few years ago research showed that for someone who has already had an illness caused by atheroslerosis, such as a heart attack, or if someone has diabetes, there is further benefit in getting the LDL below 75 mg. The ratio of LDL to HDL, once thought to be important, is not emphasized now. The reversal of atherosclerosis, which was proven by studies in the 1990’s to be possible, requires very low cholesterol; preferably an LDL below 100 mg.
Cholesterol, first discovered in 1910 to be the primary substance that makes up atherosclerosis, and modified by many factors from the genes we are born with to the food that we eat, remains the most important of many risk factors for atherosclerosis.
NORMAL (IDEAL LEVELS)
Total Cholesterol ..... < 200 mg.
LDL Cholesterol ..... < 100 mg.
..... 100 to 130 mg. is considered borderline
LDL Cholesterol if a heart attack or other atherosclerosis event has taken place < 75 mg.
LDL Cholesterol in diabetics ..... < 75 mg.
HDL Cholesterol ...... > 40 mg.
Triglycerides ...... < 150 mg.
Excess weight, dietary cholesterol, dietary fat, and poorly controlled diabetes raise LDL cholesterol. Although much has been made about polyunsatured fats vs. saturated fats since the 1970’s, studies have shown a minimum drop in switching from saturated fats to polyunsaturated fats. Polyunsaturated fats and cancer promotion is a whole different issue. Genetics strongly interact with the above factors; some obese people have low cholesterol, some thin people have high cholesterol.
Exercise and genetics raise HDL cholesterol to better levels. HDL frequently varies inversely with triglycerides.
Triglycerides are very responsive to weight gain or loss and diabetes control. An obese person can frequently get large drops in triglycerides with only a 10% weight loss.
Blood samples should be obtained after an overnight fast. Non-fasting samples can raise cholesterol a few mg. but can raise triglycerides a great deal.
OTHER RISK FACTORS
Elevated blood pressure, blood sugar (diabetes), levels of homocysteine (associated with insufficient levels of vitamin B12 or folic acid), high insulin levels (usually found in obese individuals), and vitamin D insufficiency can accelerate atherosclerosis. Elevated C-reactive protein is an indication of inflammation within the coronary arteries; levels can be lowered by the same measures used to lower LDL cholesterol.
HOW IMPORTANT ARE THE RISK FACTORS?
The notion that 50% of people suffering a heart attack have normal cholesterol levels has been spread usually by people who are selling information or products that require the minimizing of the importance of cholesterol. The way this is done is that these people take a high number, 225 mg. or 250 mg. as a "normal" cholesterol, or a high number of LDL cholesterol as "normal". This notion has been clearly disproved, but unfortunately will live on.
The truth has been shown by a study all the way back in 2003! in the Journal of the American Medical Association . A study looked at 3 comprehensive studies and concluded that 90% of coronary heart disease (CHD) had a history of elevated cholesterol, hypertension, cigarette use, or diabetes. In 2005 an Annals of Internal Medicine study showed that 8% of CHD events will actually occur with only borderline abnormal levels of multiple risk factors.