Can You Have Too Many Eggs? Demystifying Cholesterol

Most of us are familiar with the term “cholesterol,” but what exactly is it? Is cholesterol good or bad for you? Professor Anding breaks it down.

Making Cholesterol

Cholesterol technically doesn’t contain fatty acids, but it’s still classified as a fat, or lipid, because it has some of the same chemical and physical characteristics as fat. You can consume cholesterol in your diet, but it’s also made endogenously or internally by the body at a baseline rate that varies between 800 and 1500 milligrams per day. It’s made predominantly in the liver but also in other tissues such as the arteries and intestines. 

We have this master design plan that if we absolutely have to have something, often our body will create it. Cholesterol builds plasma membranes and is needed for synthesizing vitamin D, adrenal gland hormones, estrogen, androgens, and progesterone; so, it’s an essential part of every cell of your body as well as a key part of bile. 

It also helps to build tissues and organs during fetal development. However, cholesterol has no calories because it doesn’t have a fatty acid structure.

Endogenous cholesterol synthesis—the amount that’s produced in your liver—is almost always enough to meet the body’s needs, and therefore there is no dietary requirement for cholesterol. You can, however, stimulate or turn on the switch to produce cholesterol in your blood, so endogenous cholesterol synthesis increases with diets that are high in saturated or trans fats. 

You might be familiar with medications that have been on the market for the last 10 or 15 years that lower cholesterol, such as statin resins. They actually block or turn off that cholesterol switch in the liver. Many studies suggest that statin resins can significantly reduce the risk of a first heart attack.

Cholesterol and Diet

Cholesterol-rich foods are exclusively animal products, including red meats, chicken, and fish. Organ meat such as brains, kidneys, and liver are a significant source of cholesterol. Again, cholesterol is found in the cell membrane, so it’s actually in the flesh of the meat.

Shellfish—particularly shrimp—are a significant source of cholesterol, as are dairy products. Skim milk has less than five milligrams of cholesterol per serving, while full-fat milk is much higher. 

A quick rule of thumb is that each ounce of meat that you consume contains 25 milligrams of cholesterol. Any nutrition book will give you approximately the same amount of cholesterol for six ounces of chicken versus six ounces of brisket, even though they contain different saturated fat content. An egg yolk contains about 213 milligrams per egg, depending on the size of the egg. 

Foods of plant origin contain no cholesterol. A few years ago, a marketing strategy involving bananas labeled name-brand bananas with a sticker that said “no cholesterol.” Now, of course,  you know that cholesterol only comes from animals, so you won’t fall for this trick to convince you that this banana is somehow special.

Another marketing ploy is to label a can of shortening as “cholesterol-free.” While this is technically true, as shortening is a vegetable product, it is also a saturated fat, which means it is indirectly raising your cholesterol.

Further complicating matters is the fact that eating certain sources of cholesterol—for example, eggs—doesn’t necessarily translate into an increase in blood cholesterol. Thus, if we’re looking at the major switches for endogenous cholesterol production in the liver, they are saturated fat and trans fat. 

Dietary cholesterol comes in at a distant third in most research. You’ll see stories in the media that somebody ate 12 eggs a day and lived to be 105. That’s because an egg, although a rich source of cholesterol, has very low saturated fat. 

LDL and HDL

It gets a little confusing when we’re talking about cholesterol that we eat versus the cholesterol that is made in our liver. Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) are terms that many consumers have come to associate with cholesterol and heart health. 

LDL is often dubbed the “bad cholesterol” because high levels can clog your arteries. HDL is called the “good cholesterol” because it delivers cholesterol to your liver, which then removes the cholesterol from your body.

HDL and LDL are blood proteins, meaning they are not found in food. However, your diet can influence the amount of each type of cholesterol that is produced by your body.

Therefore, cholesterol is both produced naturally in our bodies and contained in the foods we eat. A diet high in saturated fat—and not necessarily cholesterol—can activate the switch that causes our body to produce more LDL.

Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Children’s Hospital. She also teaches and lectures in the Baylor College of Medicine’s Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.

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