Triglycerides and cholesterol are both a type of necessary fat found in your blood. Blood tests can measure how much of each you have in your body, and these numbers can tell you a lot about your overall health.
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But for all their similarities, there are also differences between triglycerides and cholesterol that you should know about. Here, we'll break those down.
Triglycerides vs. Cholesterol
Cholesterol is a waxy, fat-like substance in the blood, according to Harvard Health Publishing. It is critical for building cells as well as for making hormones (like estrogen and testosterone), vitamin D and digestive bile acids. The liver is the body's main source of cholesterol, though it can also come from food (called dietary cholesterol).
Triglycerides come exclusively from food, according to the Cleveland Clinic. Most dietary fats, like butter and oils, already come in the form of triglycerides. The body also turns excess calories or calories from alcohol or sugar into triglycerides and stores them as fat throughout the body. According to the American Heart Association, triglycerides are the most common type of fat in the body.
Read more: Foods to Avoid for High Triglycerides
Cholesterol and triglycerides are both fat-like substances, also called lipids. But lipids can't dissolve in blood, meaning they can't move through the body without help. So the liver packages pure cholesterol with triglycerides and proteins into tiny particles called lipoproteins, per the Cleveland Clinic.
When your doctor performs a blood test, he or she can explain the difference between your cholesterol and triglyceride levels and what that means for your health status.
Good Cholesterol vs. Bad Cholesterol
Cholesterol lipoproteins come in several different types. You may have heard cholesterol referred to as "good" and "bad" cholesterol.
Low-density lipoproteins (LDL) are considered "bad" cholesterol, according to the Mayo Clinic. If LDL cholesterol levels are too high, these particles can mix with other substances and build up as plaque in the arteries. Plaque can make the arteries more narrow and rigid, a condition called atherosclerosis. Atherosclerosis can reduce blood flow and may eventually cause a heart attack or stroke, per the Mayo Clinic.
High-density lipoproteins (HDL) help prevent the buildup of plaque. Per the Mayo Clinic, these "good" cholesterol particles move through the bloodstream and pick up excess LDL cholesterol. The good HDL then returns the bad LDL to the liver for disposal.
It was previously believed that eating cholesterol-rich foods (like animal products, particularly eggs) could raise cholesterol levels to an unhealthy level. But a major 2015 report by the USDA Dietary Guidelines Advisory Committee says that dietary cholesterol is less of a risk factor for atherosclerosis and heart disease than previously thought. However, a diet high in fatty foods and carbohydrates is a risk factor for high cholesterol and plaque buildup.
Poor diet, along with a lack of exercise, obesity and cigarette smoking are all major risk factor for high cholesterol, per the Mayo Clinic. Genetics and older age can also be risk factors.
Triglycerides and Your Health
As mentioned, the body converts unused calories into triglycerides, which are then stored as fat. This isn't necessarily a bad thing; your body uses those fat stores for energy between meals, according to the Mayo Clinic. But if you regularly eat too many calories, you will have more triglycerides — and therefore more fat — than is healthy.
Robert H. Eckel, MD, professor of medicine, emeritus, at the University of Colorado, Anschutz Medical Campus, former president of the American Heart Association and president of the American Diabetes Association, spoke with LIVESTRONG.com about the complex relationship between triglycerides, obesity and metabolic health. "Two-thirds to three-quarters of people with obesity — categorized as having a body mass index over 30 — will have mild or moderate increases in triglyceride levels [along with] metabolic syndrome," says Dr. Eckel.
Metabolic syndrome is a cluster of conditions that present a greater risk of cardiovascular disease as a group than any one of the conditions on their own, according to the American Heart Association. These conditions include high triglyceride levels, high cholesterol levels, obesity and insulin resistance.
Insulin resistance (which can cause type 2 diabetes) means the body can't properly use the hormone insulin for blood sugar regulation, according to the National Institutes of Health. It causes the liver to secrete more triglycerides into the blood, says Dr. Eckel. So, having one condition, like insulin resistance, can increase your risk of other conditions like high triglycerides and cardiovascular disease.
However, Dr. Eckel points out that not all people with obesity have metabolic syndrome. "These are the so-called 'metabolically healthy patients [with obesity],'" he says. This means that if you [have] obesity, you may have normal triglycerides or blood sugar levels. But Dr. Eckel emphasizes that this is likely temporary. "These patients tend to become more unhealthy over time," he says.
That means if you have overweight but your triglyceride levels are normal, it's still critical to take charge of your health. Don't wait for further health conditions to develop.
Read more: 11 Simple Ways to Keep Your Heart Healthy and Strong
Like high cholesterol, high triglycerides levels can also contribute to atherosclerosis, raising the risk of heart attack, stroke and death from cardiovascular disease. Per the Mayo Clinic, extremely high triglycerides levels can also cause severe inflammation of the pancreas, called pancreatitis. Additionally, high triglycerides can be a sign of hypothyroidism, type 2 diabetes and other metabolic conditions.
- Harvard Medical School: "Cholesterol"
- Cleveland Clinic: "Triglycerides and Heart Health"
- American Heart Association: "HDL (Good), LDL (Bad) Cholesterol and Triglycerides"
- Mayo Clinic: "High Cholesterol"
- USDA: "Scientific Report of the 2015 Dietary Guidelines Advisory Committee"
- Mayo Clinic: Triglycerides: Why Do They Matter?"
- American College of Cardiology: "Very High Triglycerides"
- American Heart Association: "About Metabolic Syndrome"
- National Institutes of Health: "Insulin Resistance & Prediabetes"