DO THE BENEFITS OF HDL CHOLESTEROL VARY ACCORDING TO RACE?

In the past, high levels of HDL cholesterol were thought to protect people from cardiovascular disease. However, new research indicates that this may not be the case for people of all ethnicities. 

Cholesterol is a type of fatty molecule we need in the body to form our cell membranes and help make bile salts for digestion. However, too much of the wrong kind of cholesterol can lead to problems. Read on to learn more about HDL and other types of cholesterol and what recent research findings suggest about the link between race, cholesterol, and coronary heart disease risk.

What are the different types of cholesterol?

If you are healthy, get your cholesterol checked every 4 to 6 years after 20 years of age. Your total cholesterol measured in the blood should not be higher than 200 mg/dL. The types of cholesterol and their values are of significance. Dyslipidemia is when you have harmful levels of particular kinds of cholesterol. 

There are three main types of cholesterol. These are described below, along with the levels that are believed to be unhealthy for most people.

• High-density lipoprotein (HDL): This carries cholesterol molecules away from the blood to the liver. Unhealthy levels of HDL are less than 40 mg/dL for men and less than 50 mg/dL for women.
• Low-density lipoprotein (LDL): This collects in blood vessels, forming plaques (atheroma), contributing to atherosclerosis. Unhealthy levels of LDL are 160 mg/dL and higher.
• Very-low density lipoprotein (VLDL): Similar to LDL, VLDL also contributes to plaque formation in the blood vessels. Unhealthy levels of VLDL are 30 mg/dL and higher.

What is atherosclerosis?

Atherosclerosis is a significant cause of mortality, resulting in 17 million deaths a year globally. Atherosclerosis is when there is an accumulation of plaque on the walls of arteries. As plaque accumulates, artery walls become less flexible and can become blocked. This can lead to coronary artery disease (CAD). 

A complete blockage of an artery in the brain or heart leads to a stroke or heart attack, respectively. Cholesterol and calcium, combined with inflammation are associated with atherosclerosis.

Types of cholesterol linked to atherosclerosis

Some types of cholesterol increase atherosclerosis. Low-density lipoprotein is involved in atherosclerosis and can build up in the blood, increasing plaque formation. 

The LDL cholesterol is particularly harmful and is linked with an increased risk of heart disease. While LDL and VLDL are harmful at high levels, HDL is thought to be helpful at high levels.

How HDL is beneficial

HDL helps clean the blood since it removes cholesterol and carries it to the liver. HDL also has both anti-inflammatory and antioxidant benefits. This also helps protect blood vessel walls. 

HDL levels of at least 60 mg/dL are recommended for improved health. Until recently, the benefits of HDL were thought to be the same for people of all ethnicities. However, recent research suggests this is not the case.

Correlation between HDL and race

A recent study showed that higher levels of HDL decreased coronary artery disease and coronary heart disease risk for white people, but the same could not be said for black people. Interestingly, blacks and the Japanese on average have higher HDL levels than whites. This is due to variation in a hepatic lipase gene, which is involved in how lipids are broken down. 

There may be many reasons for racial disparity in how protective HDL is in decreasing coronary artery problems and heart disease. Outlined below are a few of them: 

• Scientists have suggested that the functioning of HDL could be more relevant to the risk of developing heart disease than its level. One such factor is cholesterol efflux capacity. This is how easily HDL can remove cholesterol released into the bloodstream by macrophage cells. In general, the higher the efflux capacity, the lower the risk of atherosclerosis. 
• Another factor could be the actual particle size of molecules making up the HDL cholesterol. HDL can come in different particle sizes, and this could impact the function of the molecule. There is some research suggesting a possible difference based on ethnicity in the particle diameter of lipoproteins like HDL.

Correlation between Triglycerides, HDL, and race

According to studies, the ratio of triglycerides to HDL indicated a higher risk of coronary problems for whites but not for blacks. The ratio of triglycerides (the triglycerides are an indirect measure of VLDL) to HDL should be no higher than 2:1. A ratio that is above 3.75 is believed to increase the risk of the following:

• Hypercholesterolemia: This indicates high LDL levels in the blood. 
• Hypertriglyceridemia: This is when you have excess amounts of triglycerides in the blood. 
• Metabolic syndrome: People with metabolic syndrome have too much fat built up around their waist and they tend to have an increased risk of certain conditions like diabetes, and heart disease.
• Type 2 diabetes: Diabetes caused by insulin resistance.
• Cardiovascular disease: Heart and blood vessel disease.

In addition, there are genetic reasons for having high LDL, such as familial hypercholesterolemia.

There are race-based variations in the triglyceride to HDL ratio, with the ratio tending to be higher in Hispanics than in African Americans. It is important to understand that HDL alone is not always helpful in assessing the risk of cardiovascular disease because of differences among races. 

Correlation between LDL and race

High concentrations of LDL are still harmful to both whites and blacks, according to recent research. LDL still increases the risk of cardiovascular and coronary artery disease for everybody. Knowing the factors that increase LDL and decrease HDL can help in reducing your chance of heart and blood vessel disease.

Causes of low HDL and high LDL

High LDL is harmful and it is still best to have higher HDL because it offers some protective effect, at least for some people. Low and unhealthy HDL levels are slightly different for males and females. 

• For men, a low HDL is 40 mg/dL or lower.
• For women, a low HDL level is 50 mg/dL or lower. 

People who tend to have low levels of HDL (healthy cholesterol) and high levels of LDL (unhealthy cholesterol) in the blood include those who:

• Smoke
• Drink alcohol
• Eat lots of food high in trans fats
• Have genetic conditions like hypertriglyceridemia
• Are diagnosed with type 2 diabetes 
• Have metabolic syndrome
• Do not exercise 

Low levels of HDL, high levels of LDL, and high blood pressure increase coronary heart disease risk. Regardless of race, you should aim for a healthy lifestyle taking note of the factors mentioned above. These same lifestyle factors also increase the risk of other diseases, such as diabetes.

Correlation between Cardiovascular disease and race

There are also racial disparities in other factors that impact cardiovascular disease. 

• African Americans, for instance, tend to be more prone to hypertension than Caucasians. This could be due to genetic factors that differ between the two races. 
• South Asians seem to have genes that increase levels of triglycerides in the blood and decrease healthy HDL.
• Socioeconomic factors such as lack of access to health care are also important in influencing the risk and impact of cardiovascular disease.

How to reduce your risk of cardiovascular disease

There are ways to reduce your chances of developing cardiovascular diseases like coronary heart disease, such as:

• Exercise: Regular physical activity decreases the accumulation of unhealthy fats in the blood and helps reduce atherosclerosis. This, in turn, decreases the chances of developing coronary artery problems.
• Diet: Avoiding foods high in saturated and trans fats also decreases the harmful LDL that contributes to atherosclerosis.
• Quit smoking: Smoking increases plaque formation in blood vessels by increasing inflammation in the arteries.
• Reduce alcohol intake: Alcohol increases hypertension which is harmful to the blood vessels and the heart. It is advisable to stop drinking altogether or significantly cut down the intake.
• Reduce stress: Stress has many harmful effects on the body, including raising your blood pressure, which increases your risk of heart and blood vessel problems. 

Conclusion

According to recent research, besides other factors, how HDL helps in protecting against coronary heart disease depends on the race. The reasons for this are unclear but possibly related to how HDL functions. More research is needed in this area. Nevertheless, it is important to work on decreasing LDL and triglycerides, which are unhealthy for everyone. Changing certain lifestyle factors is helpful in reducing coronary heart disease and other cardiovascular problems regardless of race and ethnicity.

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Sources:

• Carr, M. C., Brunzell, J. D., & Deeb, S. S. (2004). Ethnic differences in hepatic lipase and HDL in Japanese, black, and white Americans: role of central obesity and LIPC polymorphisms. Journal of lipid research, 45(3), 466-473. https://www.jlr.org/article/S0022-2275(20)31874-5/fulltext
• Frazier-Wood, A. C., Manichaikul, A., Aslibekyan, S., Borecki, I. B., Goff, D. C., Hopkins, P. N., ... & Arnett, D. K. (2013). Genetic variants associated with VLDL, LDL and HDL particle size differ with race/ethnicity. Human genetics, 132(4), 405-413. https://pubmed.ncbi.nlm.nih.gov/23263444/
• Link, J. J., Rohatgi, A., & de Lemos, J. A. (2007). HDL cholesterol: physiology, pathophysiology, and management. Current problems in cardiology, 32(5), 268-314. https://www.sciencedirect.com/science/article/abs/pii/S0146280607000059
• Rohatgi, A., Khera, A., Berry, J. D., Givens, E. G., Ayers, C. R., Wedin, K. E., ... & Shaul, P. W. (2014). HDL cholesterol efflux capacity and incident cardiovascular events. New England Journal of Medicine, 371(25), 2383-2393. https://www.nejm.org/doi/full/10.1056/NEJMoa1409065
• Young, K. A., Maturu, A., Lorenzo, C., Langefeld, C. D., Wagenknecht, L. E., Chen, Y. D. I., ... & Rasouli, N. (2019). The triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio as a predictor of insulin resistance, β-cell function, and diabetes in Hispanics and African Americans. Journal of Diabetes and its Complications, 33(2), 118-122. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6331279/
• Zakai, N. A., Minnier, J., Safford, M. M., Koh, I., Irvin, M. R., Fazio, S., ... & Pamir, N. (2022). Race-dependent association of high-density lipoprotein cholesterol levels with incident coronary artery disease. Journal of the American College of Cardiology, 80(22), 2104-2115. https://www.jacc.org/doi/10.1016/j.jacc.2022.09.027

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