You’ve probably heard the warnings around having ‘high cholesterol’ and that cholesterol is unhealthy and damaging to the heart. But to what extent is cholesterol dangerous, and how do we monitor our own cholesterol?
How much is too much cholesterol?
Cholesterol is a type of fat that we all have circulating throughout our bodies. We actually require cholesterol for survival! The liver produces most bodily cholesterol (80%), while the remaining 20% is obtained through the diet. But, cholesterol in excess can cause plaque build-up in the circulatory system, narrowing blood vessels and increasing blood pressure. This narrowing or thickening of the blood vessel walls is known as atherosclerosis, which can even affect the arteries that deliver blood to the heart, contributing to coronary artery disease. Coronary artery disease consequently increases the risk of a heart attack.
Heart disease, including coronary artery disease, is actually the leading cause of death in the United States1 and the second leading cause of death in Canada.2 How do we know if our cholesterol is putting us at risk?
The HDL Ratio
Cholesterol blood levels are maintained by two types of cholesterol-carrying proteins: low density lipoprotein (LDL) and high density lipoprotein (HDL).
LDL: The “Bad” Cholesterol
LDL carries cholesterol from the liver to tissues throughout the body. The majority of the cholesterol in the blood is actually LDL-bound. If there is an excess amount of LDL-cholesterol, LDL will deposit the cholesterol along the blood vessel walls, which contributes to plaque build-up and blockage.
A 2010 study observed approximately 1000 individuals and how their risk for different forms of heart disease were affected when LDL levels decreased. For refence, the ideal LDL blood level is less than 2.6mmol/L.3 The study found that a LDL reduction by 1.0mmol/L with medication decreased the occurrence of deadly heart-related events by one-fifth per year.4 They also found that reducing LDL levels by 2-3mmol/L reduces the risk of these fatal events such as heart attack and stroke by 40-50%. Clearly, LDL-cholesterol levels contribute to a higher risk for heart disease and is indeed the “bad” cholesterol.
HDL: The “Good” Cholesterol
HDL balances out the LDL activity; it picks up cholesterol from tissues and blood vessels and brings it to the liver where it is either used or eliminated from the body. So, the ratio of HDL to LDL is an important indicator of health. What is a good cholesterol HDL ratio?
The HDL Ratio
The most common of the HDL ratios is the total cholesterol to HDL. The total cholesterol (TC) is made of LDL, HDL, and triglycerides (another common bodily fat), however the majority of the total cholesterol is LDL. Considering TC:HDL, what is a good cholesterol HDL ratio?
A study observed 6,147 healthy women aged 50-59 over a period of 17 years. Their TC:HDL levels were measured, and their corresponding risk for heart attack. It was shown that increasing the TC:HDL ratio increased the risk of heart attack significantly.5 The lowest risk for a heart attack was found when the TC:HDL ratio was less than 3.5. These findings match the guidelines set out by the American Heart Association: the TC:HDL ratio should be less than 5.0, and ideally as low as 3.5 for limited risk to heart health.
What cholesterol levels should we aim for?
A 2018 medically reviewed report from the American College of Cardiology and the American Heart Association displayed results from U.S. population studies. The report provides the following medical advice: the ideal total cholesterol is 160mg/dL (3.8mmol/L), and LDL should be less than 100mg/dL (2.6mmol/L).3 HDL or good cholesterol levels should be no less than 40mg/dL for men and 50mg/dL for women.
How can we decrease our TC:HDL?
Contrary to popular thought, eating less cholesterol does not decrease overall cholesterol levels. Eating more cholesterol has actually been shown to decrease cholesterol production by the liver, so that the total cholesterol level in the body is maintained.6 Instead of focusing on eating less cholesterol in general, raising HDL to ensure the cholesterol we do have circulating throughout our bodies is working for us, not against us.
Fat-heavy foods should be chosen wisely; saturated fats such as those found in red meat and other animal products are high in LDL-cholesterol. If dietary fat is switched to unsaturated fats, such as vegetable oils and fish, flax seeds, and nuts for example, this can help to increase HDL versus LDL.
Maintaining an active lifestyle can help keep HDL levels high. One study looked at aerobic training in 26 individuals at risk for heart disease. They observed a 13% increase in HDL levels.7 Another study with 36 men observed that those put on a prolonged moderate intense running exercise regime for 12 weeks showed a significant decrease in TC:HDL ratio at about 16%.8 Cardio-intensive exercise then can be used to help achieve a higher HDL cholesterol level.
Healthy Weight Loss
Obesity is another risk factor for a high TC:HDL ratio. A study found that those who performed exercise-induced weight loss showed a significant increase in HDL levels.9
Smoke exposure can reduce HDL levels. When one study compared smokers with those that have stopped, a reversible effect was observed. Those who stopped smoking for a year showed a significant increase in HDL levels versus a decrease in those who kept smoking.10
What is a good cholesterol HDL ratio? The TC:HDL cholesterol ratio is a valuable indicator of heart disease risk and ideally should be less than 3.5. HDL levels can be increased by consuming more plant-based fat sources, exercising regularly, managing weight, and ceasing smoking.
Cholesterol should be monitored on a regular basis; the American Heart Association recommends that adults aged 20 or older should have a cholesterol blood test every 4-6 years. Other risk factors for coronary artery disease such as age, high blood pressure, and diabetes may call for more frequent cholesterol checks. It is best to consult your family physician to determine your risk and establish an appropriate routine to monitor your cholesterol; also speak with your doctor before beginning any dietary or exercise program.
- Centers for Disease Control and Prevention. “Underlying Cause of Death, 1999-2018”. CDC WONDER Online Database. Accessed March 4 2021.
- “Heart Disease in Canada”. (2017). Government of Canada, Public Health Agency of Canada. Accessed March 4, 2021. Retrieved from https://www.canada.ca/en/public-health/services/publications/diseases-conditions/heart-disease-canada.html.
- Grudy, S. M. et al. (2018). AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of the Blood Cholesterol: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation; 139: e1082-e1143. Doi: 10.1161/CIR.0000000000000625.
- Baigent, C. et al. (2010). Efficacy and safety of more intensive lowering of LDL cholesterol: meta-analysis of data from 170,000 participants in 26 randomised trials. The Lancet Journal; 376(9753): 1670-1681. Doi: 10.1016/S0140-6736(10)61350-5.
- Calling, S. et al. (2019). The ratio of total cholesterol to high density lipoprotein cholesterol and myocardial infarction in Women’s health in the Lund area (WHILA): a 17-year follow-up cohort study. BMC Cardiovascular Disorders; 19: 239. Doi: 10.1186/s12872-019-1228-7.
- Hu, Y. et al. (2010). Regulation of cholesterol homeostasis by liver X receptors. Clinica Chimica Acta; 411(9-10): 617-625. Doi: 10.1016/j.cca.2009.12.027.
- Banz, W. J. et al. (2003). Effects of resistance versus aerobic training on coronary artery disease risk factors. Experimental Biology and Medicine; 228(4): 434-440. Doi: 10.1177/153537020322800414.
- Nybo, L. et al. (2010). High-Intensity Training versus Traditional Exercise Interventions for Promoting Health. Medicine & Science in Sports & Exercise; 42(10): 1951-1958. Doi: 10.1249/MSS.0b013e3181d99203.
- Williams, P. T. et al. (1994). The Effects of Weight Loss by Exercise or Dieting on Plasma High-Density Lipoprotein (LDL) Levels in Men With Low, Intermediate, and Normal-to-High HDL at Baseline. Metabolism; 43(7): 917-924.
- Gepner, A. D. (2012). Effects of Smoking and Smoking Cessation on Lipids and Lipoproteins: Outcomes from a Randomized Clinical Trial. American Heart Journal; 161(1): 145-151. Doi: 10.1016/j.ahj.2010.09.023.
Image by Bruno /Germany from Pixabay