The Truth About Cholesterol, Part I
Dr. Myatt and Nurse Mark field a lot of questions from Wellness Club Members, many concerning cholesterol. They have asked me to devote this newsletter to answering some of those questions.
Cholesterol seems to be a subject on everybody's lips recently, with medical scientists recommending even lower standards for cholesterol, and the pharmaceutical companies promoting an ever-increasing number of powerful cholesterol-lowering drugs. But what is this cholesterol that everyone talks about, why do we have it, do we need it, and what can we do about it?
You might be excused if you think because of all the "bad press" about the evils of cholesterol that it is a nasty, deadly foreign substance that should be avoided at all costs. Nothing could be further from the truth. Let's get clear on one thing: cholesterol is essential to life. We cannot live without it. It makes up approximately 80% of our body's cell walls! This vital substance is synthesized by the liver and is used by the body as a building block for such essential things as steroid hormones and bile acids in addition to cell membranes. Cholesterol is a precursor to Vitamin D in the skin, and without cholesterol we could not absorb the essential fat-soluble vitamins A, D, E and K from the food we eat. Cholesterol also gives the skin it's ability to shed water and is essential to the growth and maintenance of the nervous system. So we really do need cholesterol - it is not the bad thing that some would have us believe it is. Having said that, it is important to know that there are several kinds of cholesterol.
First is the "bad" cholesterol that we have all heard about, LDL or Low Density Lipoprotein. LDL carries most of the cholesterol in the blood, and this is the form of cholesterol that is now thought to be the main source of blockage and damage in the arteries. (I say "thought" because we keep changing our opinion on this. Not too many years ago, modern medicine "knew" that total cholesterol was the bugaboo). The higher the LDL level, the greater your risk for Coronary Heart Disease (CHD), or so we think. VLDL (Very Low Density Lipoprotein) performs the same tasks as LDL in terms of transporting fats (triglycerides and cholesterol) from the liver to the body's cells and so may be dangerous when elevated.
Next is the "good" cholesterol, HDL (High Density Lipoprotein). It might be described as the "anti-cholesterol" because its job is to collect cholesterol in the blood and transport it back to the liver where it ends up being eliminated from the body. HDL seems to keep LDL from building up on the walls of the arteries, so HDL / LDL ratios are considered by many to be a better indicator of "cholesterol health" and CHD risk than overall cholesterol levels. Exercise and niacin are two potent agents for keeping HDL levels high.
Finally, there are Triglycerides (TG's), which aren't exactly cholesterol - they are a form of sugar carried by a fat--- a fat/sugar molecule----that circulates in the bloodstream. High levels of triglycerides are an independent risk factor for cardiovascular disease. TG levels primarily become elevated by high intakes of dietary carbohydrates.
Humans manufacture cholesterol in the liver - remember, it is an important substance for normal body functioning. Conventional medical wisdom would have us believe that we should limit our dietary intake of cholesterol for this reason. That may be partially true, in that if the body is not producing enough HDL or "good" cholesterol to prevent the buildup of LDL ("bad") cholesterol with it's atherosclerotic effects or if the LDL receptors in the liver are not functioning properly then it might be wise to limit intake of cholesterols. In particular, dietary trans fats have been found to be extremely harmful, creating a whole cascade of damaging effects throughout the body.
There are a number of mechanisms that the body uses to control cholesterol production and therefore blood levels of cholesterol. The most important of these is in the liver where a chemical receptor senses LDL, and when it has detected "enough," tells the liver to stop manufacturing more. Damage to this important feedback control mechanism can occur through normal aging which reduces the number and efficiency of the LDL receptors, and several disease states - most importantly diabetes, and also low thyroid function. This feedback mechanism (when functioning properly) means that eating foods high in cholesterol is not risky - the intake of dietary cholesterol simply tells the liver to stop making so much of it's own! In many people, eating TOO LITTLE cholesterol causes the liver to manufacture MORE!
1.) Cholesterol in it's various forms--- LDL,HDL, VLDL and TG's, exerts various effects. We currently "think" that LDL is the most dangerous cholesterol and that HDL is protective. Keep in mind that medical opinions about cholesterol and it's effects change regularly.
2.) LDL and TG's appear to be independent risk factors for cardiovascular disease.
3.) TG's become elevated by primarily by excess carbohydrates in the diet, not by high fat or cholesterol in the diet.
4.) HDL levels can be increased by exercise, niacin, and maintaining youthful sex hormone levels.
5.) Decreased dietary cholesterol often does NOT lower total cholesterol levels; the liver simply manufactures more when it senses less intake from diet.
In Part II, Next Issue: Natural Cholesterol Cures, featuring a review of both drugs and natural substances that can be used to lower cholesterol.
Until Next Time, Be Well!
Editor, HealthBeat Newsletter