Can Your Cholesterol Be Too Low?

Many people know that low levels of "good" high-density lipoprotein (HDL) cholesterol increases the risk of heart disease. They also know that too much "bad" low-density lipoprotein (LDL) increases the risk of heart attack and stroke.

But is it possible to have "too little" LDL? Is there such a thing?

The question has long divided the medical community, with some healthcare professionals cautioning that too-low LDL levels may cause or contribute to anxiety, nervousness, or sleep problems. Then there are health experts who maintain that "for LDL, the lower the number, the better."

The fact is, research has shown that many people appear to tolerate low LDL levels very well.

Until more research can be done, it appears that momentum is building to support the latter point of view. This article explores the role of HDL and LDL and what happens if either number drops "too low."

Understanding Cholesterol

Despite its association with heart disease, your body needs cholesterol. The waxy substance is essential to making certain vitamins and hormones. It also plays a role in digestion and metabolizing nutrients. The problem is that many Americans are fond of foods that are high in saturated fats and sugar. This preference adds to the cholesterol that the liver naturally produces.

By contrast, a low-fat, low-carb diet can help maintain higher levels of HDL (which the body uses to excrete cholesterol from the body) and a lower concentration of LDL (which can clog arteries and form plaque).

HDL and LDL levels can (and should) be measured with a simple blood test. For the average American adult, the values, measured in milligrams per deciliter (mg/dL), can be put in perspective as follows:

• HDL values of 60 or higher are considered "good" while anything less than 40 is considered "low."
• LDL values under 100 are considered "optimal," between 100 and 129 are "near optimal," between 130 and 159 are "borderline," and 160 and over are "high."

Meanwhile, the American Heart Association and the American College of Cardiology support LDL levels of 100 mg/dL or less. People who are in this range tend to have lower rates of heart disease and stroke.

Other measurements on a cholesterol test include triglycerides, a type of fat in the blood, and total cholesterol, the total amount of LDL, HDL, and triglycerides.

Risks of Low HDL

From the standpoint of heart health, a total cholesterol level can never be too low. A problem arises when the HDL drops below 40 mg/dL. Quite simply, the less HDL there is in your blood, the less cholesterol you can clear from the body. This, in turn, increases the risk of atherosclerosis (hardening of the arteries), heart attack, and stroke.

There are many reasons why your HDL levels may be low. Chief among these is a high-carbohydrate diet. A diet of this sort not only affects your blood sugar, increasing the risk of insulin resistance. It can also lower your HDL while raising both your LDL and triglycerides by 30% to 40%.

Other factors associated with low HDL levels include:

• Elevated triglycerides
• End-stage kidney disease
• High-dose beta blockers
• High-dose thiazide diuretics
• Obesity and metabolic syndrome (which can lead to cardiovascular problems, heart attack, stroke, and diabetes)
• Sedentary lifestyle
• Severe liver disease
• Smoking
• Tangier disease, a rare genetic disorder associated with a severe, chronic reduction of HDL
• Type 2 diabetes
  

Malnutrition can also contribute to chronically low HDL levels.

Risks of Low LDL

While it would be fair to assume that low LDL is a good thing, there are circumstances in which chronically low levels may not be desirable.

LDL is a lipoprotein whose role it is to deliver lipids to every cell in the body. Cholesterol is a critical component of cell membranes, serves as a brain antioxidant, and is used by the body to create the hormones estrogen, progesterone, and testosterone.

Very low LDL levels during pregnancy may trigger hormonal imbalances that contribute, at least in part, to premature birth.

Abnormally low LDL, called hypobetalipoproteinemia, is often caused by cancer, liver disease, severe malnutrition, and other wasting disorders.

These are uncommon occurrences. Far more commonplace is the likelihood of people taking medication to lower their cholesterol. This may be an option if someone's LDL level is 190 mg/dL or higher. There has been some concern that these medications may drop LDL too low.

In two large medical trials, though, researchers found that LDL really can't be lowered too much. Some participants recorded LDL levels of 25 mg/dL or even lower—and reported no negative side effects.

Treatment

It's often difficult to manage low cholesterol with anything other than diet or lifestyle. There are currently no medications able to raise HDL (with the exception of hormone replacement therapy in people who have gone through menopause).

Beyond this, the best ways to get your cholesterol within normal limits is to:

• Avoid saturated fat and trans fat
• Eat plenty of fruits, vegetables, whole grains, and nuts
• Exercise regularly
• Limit red meat, processed foods, sugar, and processed flour
• Lose weight if you're overweight
• Stop (or don't start) smoking
• Take statin medications, if prescribed
  

Aim to keep your total cholesterol within the middle range, or somewhere between 150 and 200 mg/dL. And continue monitoring your levels as directed by your healthcare provider.

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Current Dietary Recommendations

You may have formed the idea that you need to avoid all dietary cholesterol. But that's not necessarily so. Specific daily cholesterol limits were removed from dietary guidelines because there isn't much evidence that cholesterol from diet affects blood cholesterol levels.

Cholesterol is a fat, and you need fat in your diet. It's the type of cholesterol-containing foods we eat that influence our risk for cardiovascular disease and cardiovascular-related illnesses. Unfortunately, most foods that are high in cholesterol are also high in unhealthy fats.

Cholesterol is just one measure of heart health. So put the full picture into perspective and choose foods with “good” unsaturated fats, avoid “bad” trans fats, and limit foods high in saturated fats:

• “Good” unsaturated fats are the monounsaturated and polyunsaturated fats that can lower your risk for heart disease. You can find these good fats in oils like olive, canola, sunflower, soy, and corn oil. Good fats are also present in fish, nuts, and seeds.
• Trans fats are "bad" fats that can increase your risk for disease even when they're consumed in small amounts. They've mostly been removed from packaged processed foods, but fried foods may contain them.
• Saturated fats aren't as unhealthy as trans fats, but they should be consumed in small doses. You should limit saturated fats from sources like red meat, fast food, and pizza.

By and large, foods that are high in cholesterol tend to be high in saturated fat, the latter of which significantly increases the risk of cardiovascular disease (CVD).

On the other hand, eggs and shellfish are high in cholesterol but low in saturated fat, making them an ideal source for the cholesterol our bodies need.

Summary

It can be tricky to keep "good" (HDL) and "bad" (LDL) cholesterol straight. HDL values of 60 or higher are considered "good" while anything less than 40 is considered "low." Meanwhile, LDL values under 100 are considered "optimal," between 100 and 129 are "near optimal," between 130 and 159 are "borderline," and 160 and over are "high."

Low HDL levels can lead to heart disease, but researchers often disagree whether it's possible for LDL levels to fall too low. A growing pile of research suggests that "lower is better" when it comes to LDL levels.