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by Jason Hoyt, Stanford University

Has there been any research about people who are fortunate to have very low cholesterol levels? My mother and I both have numbers in the low 120's from year to year, although both of us really do not do anything special as far as diet goes. I love butter and greasy potato chips! Is there any downside to a low cholesterol level?

-A curious adult from Indiana

July 2, 2008

Everyone knows high cholesterol is bad. Too much cholesterol leads to heart attacks and strokes. So lowering cholesterol if it is high is a no brainer.

Most of the studies I have seen show little or no risk with low cholesterol. The main risks are if you naturally have very low cholesterol and you fall even further. I’ll talk about a couple of studies later on that deal with this kind of situation but the studies are preliminary and may not pan out.

To understand why high cholesterol is usually bad and low cholesterol is usually good, we need to go into a bit more detail about cholesterol. And how it is used in our bodies.

Two Types of Cholesterol

Exercise increases HDL which
decreases the risk for a heart
attack.
As you probably know, there are two forms of cholesterol, HDL and LDL. It is these levels and their relationship to each other that is most important.

HDL

This is sometimes called the “good” cholesterol. HDL stands for high-density lipoprotein. HDL takes fat away from cells and other parts of our body and brings it to the liver. Once in the liver, the fat is removed from our bodies. The fat can also be changed into something else, like a sex hormone.

It is easy to see then that as HDL levels go up, our fat levels go down. So, in general, the higher the HDL the healthier we are.

LDL

We call LDL the “bad” cholesterol. It stands for low-density lipoprotein. It does the opposite job of HDL, meaning that it carries fat to various tissues of our bodies. This is necessary but too much tissue fat isn’t good for us.

In most cases, we want to lower our LDL levels to reduce our chances of heart disease. But remember, cholesterol isn’t a bad thing—we need it to live.

Cholesterol is not the Villain

Cholesterol is needed to make the outsides of our cells, make hormones, help us digest food, and many other things. People who make way too little cholesterol can have trouble with these functions.

There is still a good debate going on about low cholesterol. There is evidence that people with naturally low total cholesterol (less than 160 mg/dL) are safe. Remember that total cholesterol is the HDL plus LDL. It is the people with sudden drops in cholesterol that might be at risk, but not always.

Also, if you naturally have very low total cholesterol, but your HDL level is too low then you are still at risk for a heart attack or other disease. In other words, even with low LDL, if your HDL is too low, then you still may be at risk.

Research shows that the elderly, people with cancer, or other life-long diseases are at risk with too low cholesterol. Meaning that they do better if they slightly increase their cholesterol levels.

One recent study showed a small increase of cancer in people with very low cholesterol levels. This doesn’t mean low cholesterol was causing the cancer, but it does mean something strange is going on.

For example, there could be a change in how cells are made. Or the immune system might be weakened and no longer be able to fight off cancer cells.

Research also shows that our ability to think goes down and risk of depression increases. This could be because hormones are no longer being made, as they should. Hormones play a big role in our emotional and physical health.

As I said, though, these studies are in people who naturally have lower cholesterol that drops even further. Or in people with normal cholesterol levels who experience a big sudden drop.

In other words, no one has shown that people with naturally low cholesterol levels are in any danger unless their cholesterol levels fall even lower.

High Cholesterol is a Much Bigger Risk

Lay off greasy foods and get
some exercise.
Now having said all of this, the risks of low cholesterol appear to be pretty minor compared to the risks of high cholesterol. Not all of us are as lucky as you and your mom in this regard.

Remember, the cholesterol we have comes from the things we eat and partly from what our own bodies make in the liver. Besides our diet, cholesterol levels can change based on exercise habits and certain medications.

Here’s a quick list of how to keep your LDL cholesterol low and HDL high:

Read your food labels and look out for too much saturated fat. Saturated fat increases LDL levels. Unsaturated fats are generally better for us since they help increase HDL levels
Only 30% of all your daily calories from food should come from fat.
Eat more fruits and vegetables.
If you do eat meat, make sure it is lean and remove the skin from chicken.
Exercise to increase your HDL
When needed, your doctor can provide LDL lowering medicines such as statins

Your total cholesterol level, or LDL plus HDL, should be below 200 mg/dL. That means 200 milligrams per 10 liters of blood. For some people it might be okay to be over 200 and your doctor will talk to you about it.

The best advice, even if you have naturally low cholesterol, is to avoid eating too many of those tasty potato chips and keep exercising.

Jason Hoyt

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