Table of ContentsView AllTable of ContentsOverviewGood and Bad CholesterolCauses of High CholesterolTriglycerides and Cardiac RiskTestingWhen to Seek Treatment
Table of ContentsView All
View All
Table of Contents
Overview
Good and Bad Cholesterol
Causes of High Cholesterol
Triglycerides and Cardiac Risk
Testing
When to Seek Treatment
Everywhere you turn, you are admonished to pay attention to your cholesterol levels, and to a lesser extent, your triglyceride levels. Cholesterol and triglycerides are two forms of lipid, or fat, that circulate in your bloodstream. They are both necessary for life itself.
Cholesterolis critical for building and maintaining key parts of your cells, such as your cell membranes, and for making several essential hormones — including the estrogens, progesterone, vitamin D, and steroids. Triglycerides, which are chains of high-energy fatty acids, provide much of the energy needed for your tissues to function. So you can’t live without either of these types of lipids.
But when blood levels of cholesterol or triglycerides become too high, your risk of developing heart attack,stroke, andperipheral vascular diseaseis significantly increased. And this is why you need to be concerned about your lipid levels.
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There are two sources for cholesterol and triglycerides — dietary sources and “endogenous” sources (manufactured within the body). Dietary cholesterol mainly comes fromeating meatsanddairy products. Triglycerides come from eating extra calories, particularly carbohydrate-rich foods (like sweets). These dietary lipids are absorbed through your gut and then are delivered through the bloodstream to your liver, where they are processed.
Your liver then places the cholesterol and triglycerides, along with special proteins, into tiny sphere-shaped packages calledlipoproteins, which are released into the circulation. Cholesterol and triglycerides are removed from the lipoproteins and delivered to your body’s cells, wherever they are needed.
Excess triglycerides — those that are not needed immediately for fuel — are stored in fat cells for later usage. It is important to know that many of the fatty acids stored in our bodies originated as dietary carbs. Because there is a limit to how many carbohydrates we can store in our bodies, any “extra” carbs we eat are converted to fatty acids, which are then packaged as triglycerides and stored as fat. (This explains why it is easy to become obese even on a low-fat diet.) The stored fatty acids are split from the triglycerides and burned as fuel during periods of fasting.
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You will often hear doctors and dietitians talk about two different “types” of cholesterol —low-density lipoprotein (LDL) cholesterol(so-called “bad” cholesterol), and high-density lipoprotein (HDL) cholesterol (or “good” cholesterol). This way of talking about cholesterol is a convenient shorthand, but strictly speaking, it is not really correct.
Strictly speaking, as any good chemist will tell you, cholesterol is just cholesterol. One molecule of cholesterol is pretty much the same as another. So why do doctors talk about good and bad cholesterol?
The answer has to do with lipoproteins.
Lipoproteins.Cholesterol (and triglycerides) are lipids, and therefore do not dissolve in a water medium like blood. In order for lipids to be transported in the bloodstream without clumping together, they need to be packaged into small particles called lipoproteins. Lipoproteins are soluble in blood, and allow cholesterol and triglycerides to be moved with ease through the bloodstream.
LDL Cholesterol — “Bad” Cholesterol.In most people, the majority of the cholesterol in the blood is packaged in LDL particles. LDL cholesterol is often called “bad” cholesterol.
While lowering LDL cholesterol levels withstatin drugssignificantly reduces cardiac risk, reducing LDL cholesterol levels with most other kinds of drugs has not been shown definitely to do so.Current guidelines on treating cholesterolrely so strongly on the use of statins because they don’t just lower cholesterol but contribute to plaque stabilization and have possible anti-inflammatory effects.
“HDL Cholesterol — Good” Cholesterol.Higher blood levels of HDL cholesterol levels are associated with alowerrisk of heart disease, and conversely, low HDL cholesterol levels are associated with an increased risk. For this reason, HDL cholesterol is commonly called “good” cholesterol.
It appears that the HDL lipoprotein “scours” the walls of blood vessels and removes excess cholesterol. So the cholesterol present in HDL is, to a large extent, excess cholesterol that has just been removed from cells and blood vessel walls and is being transported back to the liver for recycling. Thehigher the HDL cholesterol levels, presumably, the more cholesterol is being removed from where it might otherwise cause damage.
In recent years, the notion that HDL cholesterol is always “good” has come under fire, and indeed, it now appears that the truth is a bit more complicated than simply “HDL = good cholesterol.” Drug companies working hard to devise drugs for increasing HDL levels, for instance, so far have run into a brick wall. Several drugs that successfully raise HDL levels have failed to improve cardiac outcomes. Results like these are forcing experts to revise their thinking about HDL cholesterol.
Several medical conditions, includingdiabetes,hypothyroidism, liver disease, and chronic kidney failure can also increase cholesterol levels. Some drugs, especially steroids and progesterone, can do the same.
Still, there is no question that hypertriglyceridemia is strongly associated with elevated cardiovascular risk. Furthermore, high triglyceride levels are a prominent feature of several other conditions known to increase cardiac risk. These include obesity, sedentary lifestyle, smoking, hypothyroidism — and especiallymetabolic syndromeand type 2 diabetes.
This latter relationship is particularly important. Theinsulin resistancethat characterizes metabolic syndrome and type 2 diabetes produces an overall metabolic profile that tremendously increases cardiac risk. This unfavorable metabolic profile includes, in addition to hypertriglyceridemia,elevated CRP levels, high LDL cholesterol levels, and low HDL cholesterol levels. (In fact, there is usually a “see-saw” relationship between triglyceride and HDL cholesterol levels — the higher the one, the lower the other.) People with insulin resistance also tend to have hypertension and obesity. Their overall risk of heart disease and stroke is very high.
Beginning at age 20, testing for cholesterol and triglycerides is recommended every five years. And if your lipid levels are found to be elevated, repeat testing should be done yearly.
Deciding on whether you ought to be treated for high cholesterol or high triglyceride levels, whether that treatment ought to include drug therapy, and which drugs ought to be used is not always entirely straightforward. Still, if your cardiovascular risk is elevated, the right treatment aimed at your lipid levels can substantially reduce your chances of having a heart attack, or even of dying prematurely. So when it comes to treating cholesterol and triglycerides, it is important to get it right. You can read about current thinking onwhen and how treatment for blood lipids should be chosen.
A Word From Verywell
9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Centers for Disease Control and Prevention.How and When to Have Your Cholesterol Checked.
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