The Top Cholesterol Facts
Since you will see the word “cholesterol” on just about every food package you buy, it’s important to know what it is, what it does, and how much is safe. Below are the important cholesterol facts you need to know.
What cholesterol is
Cholesterol is not a fat. Biochemically it’s called a “sterol.” It contains no calories, so the body cannot derive any energy from it. Cholesterol forms an integral part of the cell membranes throughout your body, sort of like the mortar that holds the brick wall together. It is particularly important in the cellular structure of the brain and central nervous system, and is an important component of the myelin sheath that provides insulation to the nerves. The body uses cholesterol to make bile acids, which are necessary for proper food digestion. It’s also a vital part of adrenal and sex hormones (estrogen, progesterone, testosterone), and it helps the body manufacture vitamin D.
Only the cell membranes of animal tissue contain cholesterol. Cell membranes of plants are composed of fiber, not cholesterol. When you see “no cholesterol” on a package of fruit, vegetables, grains, or even vegetable oil, don’t believe that the manufacturer has done you a favor by removing the cholesterol. There was no cholesterol in these foods to begin with. While cholesterol is essential to life, the body makes all the cholesterol it needs. You can live quite well, even better, with eating little or no cholesterol.
What cholesterol does
Cholesterol enters the body from saturated fats in animal sources, such as meat, poultry, egg yolks, liver, butter, cheese, and other dairy products. The cholesterol goes to the liver where it joins the cholesterol that is made there. It is transported from the liver to the cells by low-density lipoproteins (LDL), which acts like a nutritional ferry boat; loading up the cholesterol and navigating through the bloodstream, stopping at cells and depositing it to the cells that need it. If a cell already has enough, it “refuses delivery” of the cholesterol cargo. The excess LDL stays in the blood where the cholesterol is deposited in the walls of arteries, causing atherosclerotic plaque. The more plaque that builds up, the narrower the arteries become, until eventually the blood supply to vital organs is reduced. This is why LDLs are known as the “bad cholesterol.”*
But take heart, a nutritional rescuer is also present in the bloodstream, the high density lipoproteins, or HDLs. These are known as “good cholesterol,” since they travel like a vacuum cleaner through the bloodstream, picking up excess cholesterol in the bloodstream, and also possibly sucking the cholesterol from the fat-laden plaques. The HDLs carry this excess cholesterol back to the liver, which converts it to bile, which is eliminated into the intestines. How your liver handles cholesterol is determined primarily by genetics, and secondarily by your diet.
While this is an oversimplification of a complicated biochemical process, it helps us understand two conclusions:
- Any diet that raises cholesterol and LDLs and/or lowers HDL is bad.
- Any diet that lowers cholesterol and/or raises HDL is good.
How much cholesterol do you need?
If your body has just the right amount of cholesterol, HDL, and LDL, it is in cholesterol balance. But how much is the right amount?
Home-made vs. dietary cholesterol
For most people, about 80 percent of the cholesterol in their blood is made by their own body, with the rest coming from their diet. In fact, your body needs cholesterol so much that it makes around 3,000 milligrams per day that’s ten times the maximum recommendation for daily dietary cholesterol. It is estimated that around thirty percent of people are sensitive to the cholesterol-raising effects of dietary cholesterol. Normally, when a healthy person eats high cholesterol foods, the liver reduces its own cholesterol production to keep blood cholesterol at a healthy level. In cholesterol-sensitive individuals, this internal monitoring mechanism doesn’t operate, so that their blood cholesterol level goes up when they eat high-cholesterol foods.
One theory that explains cholesterol sensitivity is humans are by nature vegetarians. Originally, human bodies were not genetically equipped to metabolize dietary cholesterol, since plants are cholesterol-free. As the human diet began to include animal products, some people’s bodies developed metabolic ways to dispose of excess cholesterol and some didn’t. People who descended from the ones that didn’t adapt are the cholesterol-sensitive ones.
Gender difference with cholesterol
Women tend to have higher levels of HDL than men, since female sex hormones release HDL and male sex hormones lower HDL. At menopause, estrogen production drops, and so does HDL. Just another mid-life biochemical quirk that should stimulate menopausal-age women to start an HDL-raising exercise program.
Dr. Sears, or Dr. Bill as his “little patients” call him, has been advising busy parents on how to raise healthier families for over 40 years. He received his medical training at Harvard Medical School’s Children’s Hospital in Boston and The Hospital for Sick Children in Toronto, the world’s largest children’s hospital, where he was associate ward chief of the newborn intensive care unit before serving as the chief of pediatrics at Toronto Western Hospital, a teaching hospital of the University of Toronto. He has served as a professor of pediatrics at the University of Toronto, University of South Carolina, University of Southern California School of Medicine, and University of California: Irvine. As a father of 8 children, he coached Little League sports for 20 years, and together with his wife Martha has written more than 40 best-selling books and countless articles on nutrition, parenting, and healthy aging. He serves as a health consultant for magazines, TV, radio and other media, and his AskDrSears.com website is one of the most popular health and parenting sites. Dr. Sears has appeared on over 100 television programs, including 20/20, Good Morning America, Oprah, Today, The View, and Dr. Phil, and was featured on the cover of TIME Magazine in May 2012. He is noted for his science-made-simple-and-fun approach to family health.