In the past many doctors would have said, “Heart disease is all about getting the bad cholesterol down (LDL) and the good cholesterol up (HDL)."
It’s is not that simple it turns out. Now we are re-thinking the gospel of ‘good’ and ‘bad’ cholesterol for many reasons. Several new drugs that raised HDL and lowered LDL (Torcetrapib, Dalcetrapib and Evacetrapib) should have been a gift to all with heart disease risk factors, but sadly they either lead to an increase in heart disease or no change so they never made it to market. On the other hand, lifestyle changes that slightly lowered HDL reversed heart disease. Given these two big research findings we have had to re-look at the ‘good’ cholesterol HDL.
The truth is that HDL can be good, bad or neutral. When it comes to preventing and reversing heart disease, it’s about much more than just cholesterol. Heart disease (more specifically: coronary artery disease/atherosclerosis/clogged arteries) is the accumulated result of lifestyle choices in most people who have it (the exception being a few rare individuals with truly challenging genetics).
Understanding HDL
HDL has two main functions: Reverse Cholesterol Transport (Efflux Capacity) and HDL’s Pro or Anti-Inflammatory effects.
Why did we think high HDL was good? Because usually it is. The body makes HDL to remove excessive cholesterol from blood and tissues, a process known as “reverse cholesterol transport.” Think of HDL like the garbage trucks of your body. HDL transports cholesterol back to your liver, where it is converted into hormones or metabolized and removed from your body. Your body’s ability to raise HDL, or make more garbage trucks is, in part, genetically determined. Some people can make more HDL than others.
Most Americans eat a diet that’s relatively high in saturated fat and cholesterol—a lot of “garbage.” Those people who have a lot of garbage trucks—those who have high HDL levels—are more efficient at getting rid of extra fat and cholesterol in their diet. As a result, they have a lower risk of a heart attack or stroke than those who eat a high-fat, high-cholesterol diet who have lower HDL levels. However, the relationship of HDL to risk of heart disease and stroke assumes that people are not changing their diet.
Not Everything That Raises HDL Is Good For You
For example, if you increase the amount of fat and cholesterol in your diet (e.g., an Atkins diet and some versions of the Paleo diet), you may increase your HDL, because your body is trying to get rid of the extra “garbage” (fat and cholesterol) by increasing the number of available garbage trucks (HDL), if you are genetically able to do so. Eating a stick of butter will raise HDL in those who are able to do so, but that does not mean that butter is good for your heart. It isn’t.
Not Everything That Lowers HDL Is Bad For You
If you change from a high-fat, high- cholesterol diet to a healthy low-fat, low-cholesterol diet, your HDL levels may stay the same or even decrease because there is less need for it. When you have less garbage, you need fewer garbage trucks to remove it, so your body may make less HDL. Thus, a reduction in HDL on a low-fat diet is not harmful.
We know this to be true because in our studies we looked at outcomes (plaque regression, blood flow and cardiac events) in addition to blood markers like LDL and HDL. We found that even though participants HDL levels decreased, these patients showed reversal of their heart disease.
We also know this because of studies done looking at Efflux Capacity (HDL’s ability to return cholesterol to the liver for processing) have found that it is correlated with decreased heart disease risk, but not with HDL level. Further, findings from a large, six prospective cohorts study indicate that individuals with genetically-determined higher HDL levels throughout life have no less heart disease than those who have genetically-determined lower levels because these genetically determined levels are not related to its Efflux Capacity. Unfortunately, there is currently no easy way for a person to get their efflux capacity measured outside of the research arena.
The other role of HDL is its effect on inflammation. Both on the blood vessel wall (affecting the number of WBC’s there) and on LDL (affecting its ability to cause plaque build-up). HDL can have either anti-inflammatory properties (good) or sadly pro-inflammatory properties (bad). These antioxidant and anti-inflammatory properties of HDL may be as important as its cholesterol efflux function in terms of protecting against the development of atherosclerosis.
These anti- or pro-inflammatory properties are affected by diet and exercise. This was studied in 22 overweight/obese men with cardiovascular risk factors in a low fat diet and exercise intervention studying the inflammatory and anti-inflammatory properties of HDL and found that HDL’s characteristics converted from pro-inflammatory to anti-inflammatory state despite a quantitative reduction in HDL. These data indicate that intensive lifestyle modification improves the function of HDL even in the face of reduced levels, suggesting an increased turnover of pro-inflammatory HDL.
Summary
A decrease in circulating HDL levels in the context of a healthy low-fat diet has a very different prognostic significance than a low HDL level in individuals eating a high-fat, high-cholesterol diet. This has been found to be true both in outcome studies and studies about HDL mechanism of action.
The mechanisms that could explain HDL’s apparent ability to function better despite lower levels on a healthy lifestyle program and low-fat diet likely include:
- A more favorable ratio of LDL/HDL, despite the decrease in HDL, LDL decreased proportionally more
- Improved cholesterol efflux capacity allowing more efficient transport of cholesterol away from macrophages and back to the liver
- Improved anti-inflammatory effects of HDL directly on the arterial wall
- HDL’s effect on decreasing the recruitment of inflammatory cells into the blood vessels
How to Think About Your Heart Disease Risk
Though you can check your HDL level and basic markers of inflammation, there are no good tests that your provider can order to check for efflux capacity. Instead, we need to think about the environment that the cholesterol is living in, namely you. The reason is that it is the environment determines if the cholesterol: both the ‘good HDL’ and the ‘bad LDL’ behaves as good (promoting reversal), bad (promoting plaque) or neutral.
Do you face any of these challenges?
- Inflammation (from autoimmune diseases, poor gut health, chronic infections)
- Oxidation (from eating trans fats or rancid oils, overcooked or highly processed food, high stress living)
- Compromised blood vessels lining. (from insulin resistance or diabetes, from poor nutrient foods or high levels of pesticides or other toxins)
- A family history of relatives who have had heart attacks before the age of 50 years-old (may indicate that you have a stronger genetic risk)
- Other risk factors (obesity, high blood pressure, poor vegetable intake, smoking, sedentary, high stress, isolation)
If you have one or more of these issues then it is likely affecting the way your HDL is acting in your body as either good, bad or neutral. This is regardless of the number/level. Your level, though helpful, is not a report card in and of itself. The take home message is to change your lifestyle in the direction of one that has been proven to reverse many of these issues using a plant based diet, healthy movement, relaxation and connecting with people you care about.
Next, learn more about the way exercise can benefit your cholesterol levels. Read How to Get a Leg Up on Peripheral Artery Disease.
This content was originally published on Ornish Living.
