What is cholesterol and what are 'normal' levels?

Here's what you should know about the difference between HDL and LDL cholesterol and how to lower it to safe levels.

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/ Source: TODAY
By Madelyn Fernstrom

Americans are inundated almost on a daily basis by information about the dangers of cholesterol. Still, an estimated 102 million adults in the U.S. have a cholesterol level putting them at risk for heart disease. Even though we know we should watch our cholesterol levels, many of us don’t know how. To raise your cholesterol IQ, we’re going to take a closer look at cholesterol and find out how we can maintain healthy levels.

What is cholesterol and what does it do?

The liver combines substances from natural compounds found in your body to produce cholesterol. That’s the main source of cholesterol. But you also ingest cholesterol when you eat foods containing animal fat. These include full-fat dairy products (butter, cream, cheese, whole milk); lard; fatty meats (with visible white fat), bacon, and foods made with trans-fat (processed baked goods, fries, onion rings, etc.) In contrast, foods made plants are cholesterol free.

Accumulation of cholesterol in blood vessels makes it harder for oxygen and blood to reach your organs. It can lead to high blood pressure, stroke and heart disease. Getty Images

Our bodies need a small amount of cholesterol to maintain normal body functions, including producing hormone, processing of fat-soluble vitamins, and maintaining cell structure. While cholesterol is a specific compound, it is transported throughout the body by carriers called lipoproteins.

Depending on the carrier, cholesterol is either “good” or “bad.” High-density lipoproteins, or HDLs, carry cholesterol out of the blood to the liver, so it doesn’t stick to blood vessel walls and clog them. HDL is referred to as “good cholesterol” (think H for healthy). Low-density lipoprotein, or LDL (think lousy), on the other hand, is the “bad” cholesterol. LDL cholesterol can build up in blood vessel walls, contributing to heart disease. A few other carriers make up the total cholesterol number, but HDL and LDL two are the main components.

What are 'normal' cholesterol levels?

The only way to know your cholesterol levels is through a blood test. You need to know your total cholesterol (including the biggest contributors, LDL and HDL), as well as HDL and LDL. Triglycerides are another type of fat, related to, but different from cholesterol. High levels of triglycerides are also linked to heart disease. Here are what the numbers mean:

Total cholesterol:

  • Less than 200 is desirable
  • Between 200 and 239 is borderline high
  • From 240 up is considered high

LDL (bad cholesterol):

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  • Less than 100 is optimal (NOTE: less than 70 for those with heart disease)
  • Between 100 and 129 is almost optimal
  • Between 130 and 159 is borderline high
  • Between 160 and 189 is considered high
  • And 190 and above is deemed to be very high

HDL (good cholesterol):

  • 60 and above is optimal
  • Less than 40 for men is considered low
  • Less than 50 for women is considered low

Triglycerides

  • Less than 150 is normal
  • Between 150 and 199 is considered borderline high
  • Between 200 and 499 is high
  • And 500 or higher is very high

What can high cholesterol do to the body?

There are a number of side effects of high cholesterol. If arteries get clogged, oxygen-rich blood has trouble getting to the heart, damaging the heart muscle. Clogged arteries can also contribute to strokes, peripheral vascular disease, and peripheral artery disease (clogging in the legs and feet.) High cholesterol can contribute to high blood pressure. Accumulation of cholesterol in blood vessel walls decreases their diameter vessels, so blood is pumped through them at a higher pressure.

What factors affect cholesterol level?

Diet:

  • Cut down on saturated fat and high-cholesterol foods.
  • Eat fruits, vegetables and whole grains (fiber is good). Oatmeal is particularly good choice.
  • Avoid full-fat dairy products. Instead, opt for skim milk, lower fat cheese, lower fat yogurt and trans-fat free spreads.
  • Substitute heart healthy plant oils for butter and lard.
  • Eat lean proteins: fish, skinless chicken, and lean meats. Avoid marbled meats and bacon.

Exercise:

  • Body weight: Losing weight can help lower cholesterol. Regular exercise can increase HDL (healthy cholesterol) and lower LDL (bad). Thirty minutes per day can have healthy benefits.
  • Smoking: Don’t do it.

Biology: We can’t control

  • Age: As we all age, cholesterol rises.
  • Gender: After menopause, women are at greater risk for higher cholesterol.
  • Heredity (family tree): Your genes can determine how much cholesterol your liver produces.
  • Diabetes: This disease can alter the balance of LDL and HDL cholesterol.

How to lower high cholesterol:

  • Change your lifestyle for six months to see if this lowers your cholesterol.
  • When lifestyle isn’t effective, your doctor may prescribe medication. There are two types: statins, which act on liver to block production of cholesterol (Lipitor, Zocor, Pravachol, for example) and blockers of cholesterol absorption in digestive track — not on the liver directly. The new drug, Zetia, is an example of a blocker. Others include niacin, bile acids, and fibric acid derivatives.

Medication does not replace the lifestyle change. You can’t eat bacon and eggs for breakfast just because you take a statin. Both are both important.

NOTE: If you take cholesterol-lowering meds, like the statins, you need to avoid certain foods which can interfere with their effectiveness. For instance, don’t take them with grapefruit juice.

The bottom line: Find out your cholesterol numbers. See your doctor for a blood test. If they’re out of balance, evaluate your options. Start with lifestyle changes: diet and exercise. If that doesn’t work, then see your doctor about medications that would be safe and effective for you.

Editor's note: This is an updated version of an article previously published in 2007.