What Your Cholesterol Numbers Really Mean
In the past, LDL was the “bad cholesterol” and HDL was the “good cholesterol.” This is an interesting story that I learned in my lipid class in graduate school 13 years ago, but the science has evolved since then. For example, high HDL levels are no longer automatically good. Let’s take a look at what your cholesterol level actually means.
The most common way to get these numbers, called the lipid bar, gives you a report on total cholesterol, LDL, HDL, and triglycerides. As a result, your doctor may give a high five or seriously talk about “lifestyle changes” and even medications that lower cholesterol. The American Heart Association recommends checking your lipid levels at least every five years, and more often if your numbers indicate any concern.
A lipid pad is one of the primary ways doctors monitor your risk of atherosclerosis , a plaque build-up on the walls of arteries that narrows and strengthens these blood vessels and increases the chances of plaque or blood forming. a clot that blocks blood flow. It can cause damage anywhere in the body, but if it happens in the coronary artery of the heart , you could get a heart attack. If this happens in the brain, you may end up with a stroke.
Atherosclerosis is caused in part by cholesterol and triglycerides (fat) circulating in your blood, and the lipid panel is like a window showing how much cholesterol is circulating and what is going on.
Total cholesterol is not an important part
It’s not fair that cholesterol has become something of a curse because it’s a vital molecule in the human body. It is an important component of cell membranes, part of bile (required for the digestion of fats) and a precursor to vitamin D and several hormones, including cortisol, estrogen, and testosterone.
Just because cholesterol is important doesn’t mean we need to eat a ton of it. In fact, we don’t need to eat it at all, because our body can produce all the cholesterol we need. But if you’re not vegan, cholesterol is also a part of your diet, as it is found in foods with animal fats such as meat, fish, eggs, milk, and butter. For decades, US dietary guidelines have recommended limiting cholesterol intake, but we now know that cholesterol intake has little effect on the amount in our blood because cholesterol synthesis in the body decreases when we eat a lot of cholesterol. … The latest dietary guidelines for Americans do not recommend limiting cholesterol in their diet. (However, they say we should limit saturated fat in our diets, and most animal fats are also high in saturated fat – eggs and fish are notable exceptions.)
Your blood lipid test will give you a total cholesterol value, but that number alone means little. On its website, the American Heart Association (AHA) does not even give a range for normal total cholesterol, stating, “These ranges are not currently used. Instead, total cholesterol is viewed in the context of other risk factors and treatment is recommended accordingly. ”
Traditionally, total cholesterol levels below 200 mg / dL have been considered healthy, and Dr. Ali Rahimi, a cardiologist at Kaiser Permanente in Atlanta, says he still enjoys seeing total cholesterol under that mark.
But more important than total cholesterol is how it is packaged and where it goes in the body. This brings us to LDL and HDL. They are both types of lipoproteins , vehicles that carry cholesterol and other lipids through the blood, but each has a different function and therefore has a different effect on our health.
Bottom line : Ideally, this number should be below 200 mg / dL, but total cholesterol doesn’t really matter much; other numbers on your report are important to your health.
LDL is bad
LDL is high in cholesterol because their job is to transport cholesterol from the liver to all other cells that need it. This is important work, but LDL can also cause atherosclerosis, so too much blood circulation is not good. This is where the reputation for “bad cholesterol” LDL comes from, and it’s probably justified. People with high LDL cholesterol are more likely to develop atherosclerosis and heart disease, and lowering LDL cholesterol with drugs (usually statins) or lifestyle changes reduces this risk.
Your doctor or lab results will likely tell you that your LDL cholesterol should be below 130 mg / dL. However, cardiologists use this value more subtly than they did five years ago. “We used to be very, very focused on looking at the exact amount and thinking that less is more, and then we started pharmacotherapy at certain [higher] levels,” Rahimi said.
If your LDL is above 190 mg / dL it is considered very high and the AHA recommends statin treatment regardless of other factors. But below that number, the AHA views LDL as one of many risk factors, including factors such as smoking, diabetes, high blood pressure, and a family history of premature coronary heart disease, which increase the risk of heart disease and may increase the risk of heart disease. the urgency of taking medications that lower cholesterol levels. This should be discussed with your doctor, but you can also use this online calculator to calculate your risk. (This calculator and other versions require a minimum age of 40 because the equations behind it were not validated for a younger age. If you are younger than that age, simply enter 40 and understand that the risk estimate may be less reliable. Risk calculators from the Mayo Clinic and Kaiser allow entry for younger ages, although they can have the same degree of uncertainty when calculating risk to young people.)
Rahimi says the goal is to have an LDL level below 130, and if you drop somewhere between 130 and 190, whether he recommends drugs or not will depend on all of these other risk factors. But nonetheless, people in this range may benefit from quitting smoking, exercising more, and improving their diet, and Rahimi prefers to start with this approach if possible. These changes can lower your LDL cholesterol levels by as much as 30 mg / dL, he says, and that’s an incredibly healthy jump whether you need medications to lower your cholesterol or not.
Bottom Line: LDL is still the “bad” cholesterol, and the result is well under 130 mg / dL. Lifestyle changes and medication can help, and you are more likely to be prescribed medication if your LDL cholesterol is above 190 mg / dL.
HDL is not as useful as we would like
HDL has a well-deserved reputation for a long time. It flushes out old and excess cholesterol around the body, including fatty plaques in the arteries, and returns it to the liver for recycling and disposal. People with lower HDL levels tend to have a higher risk of heart disease, so the obvious takeaway was that the more HDL cholesterol, the better. (Traditionally healthy HDL levels were 40 mg / dL or higher for men and 50 mg / dL or higher for women.)
But this is where science has been surprising for the past few years. It was hoped that several drugs that increase HDL levels would help prevent heart disease, but these have failed in clinical trials . (In fact, some of them turned out to be doing more harm than good .) Genetic studies have also shown that having genes that raise HDL levels does not necessarily protect us from heart disease.
“It was a big ‘Aha! “A moment in cardiology,” Rahimi said. “We had to kind of rethink [HDL], and instead of being causal, it could be more of a related factor.”
In other words, if you have very high HDL levels, it may or may not indicate that you have a lower risk of heart disease, because there are some genetic reasons for high HDL levels that make HDL cholesterol not functioning properly.
Likewise, if you have low HDL cholesterol, it may indeed mean that you have an increased risk of heart disease, but probably not because of a lack of HDL cholesterol. “It’s kind of like a marker,” Rahimi said. “People with low HDL levels are more likely to be sedentary, may be smokers, may have higher insulin resistance,” so your doctor may talk about addressing these issues rather than trying to raise HDL as the ultimate goal.
“The classic good cholesterol-bad cholesterol is really missing,” Rahimi said.
However, HDL is still an active area of research. Scientists are working on measuring different types of HDL to see if some are more beneficial than others, and someday genetic tests may help us better interpret our lipid panel readings.
Bottom line : HDL is probably not a very useful number at this point.
Triglycerides Tell a Story Too
The last value you see in the lipid bar is for your triglycerides. Normal triglyceride levels are less than 150 mg / dL, and higher values are associated with an increased risk of heart disease. (Unlike HDL, this link is supported by genetic research , but overall there is little research on triglycerides.) However, Rahimi says that it is only when triglyceride levels rise above 500 mg / dL that he begins to consider medications. (The drugs used include statins, fibrates, niacin, and high doses of fish oil.) Between 150 and 500, he talks about a lifestyle change towards lowering triglycerides.
“When we see higher triglyceride levels, we worry about the person’s diet,” Rahimi said. One of the main contributors to high triglyceride levels is carbohydrate intake, especially sugar. Obesity and insulin resistance, which can lead to diabetes, also cause triglyceride levels to rise, as does excessive alcohol consumption.
Bottom Line : Triglycerides should ideally be below 150 mg / dL and you can lower this level with diet. Above 500 mg / dL, you will most likely be prescribed medication.
Small numbers, big picture
The blood lipid panel remains the main method for assessing the risk of heart disease. The great thing about these values is that they are quantifiable and tracked over time. However, they also have limitations. Some lipid values are more useful than others, and none of them exist in a vacuum. They are influenced by many factors, some of which you can change and some of which you cannot, including genetics. We’re still trying to understand them, and we probably should have known better than thinking that biology can be as black and white as good cholesterol and bad cholesterol.
NOTE. This article was updated on 4/4/18 to include information on the minimum age for heart risk calculators [12:47 pm EDT] and to emphasize that this is a very high HDL associated with certain genetic variants that may not be associated with a lower heart disease risk [18:38 EDT].