Cholesterol and Its Role in Our Health: What You Need to Know

Understanding Cholesterol and Its Impact on Heart Health

If you've ever had a routine check-up, your doctor has likely ordered a blood test to assess key health markers, including cholesterol levels. Cholesterol is essential for cell function, hormone production, and digestion, however, high cholesterol can increase the risk of heart disease and stroke. High cholesterol typically has no noticeable symptoms, making it a silent risk factor that can go undetected until serious health issues arise. It can affect anyone and may result from a combination of factors, some within our control and others not. This is why routine cholesterol checks are essential for maintaining heart health and preventing complications before they occur.

Controllable factors include:

• Diet: Excess saturated fat can hinder the liver’s ability to remove cholesterol, causing it to accumulate in the blood.

• Physical activity: Regular exercise helps lower cholesterol.

• Smoking: Smoking not only raises cholesterol levels but also damages arteries, making it easier for cholesterol to stick to them.

Uncontrollable factors include:

• Age: Cholesterol levels tend to rise with age.

• Sex: Males are more prone to high cholesterol.

• Ethnicity: Black African, African Caribbean or South Asian heritage increases the risk of high cholesterol.

• Genetics: Conditions like familial hypercholesterolemia (FH) and elevated lipoprotein (a) can be inherited, leading to high cholesterol regardless of lifestyle.

• Health conditions: Kidney or liver disease, excess weight, type-2 diabetes, hypothyroidism, and growth hormone deficiencies can also contribute to high cholesterol levels.

Understanding these factors can help you manage and reduce your risk of high cholesterol and its associated complications.

Types of Cholesterol-Carrying Lipoproteins

Since cholesterol is not water-soluble, the body packages it into lipoproteins to transport it through the blood.

Image sourced from: bhf.org.uk

The most commonly discussed lipoproteins are:

• LDL (Low-Density Lipoprotein): LDL plays a crucial role in transporting cholesterol to cells, but when LDL levels are too high, excess particles can penetrate artery walls. Once inside, they trigger an immune response, where white blood cells engulf the cholesterol, forming foam cells. This process leads to inflammation, plaque buildup, and ultimately, atherosclerosis—a key driver of cardiovascular disease.

Image sourced from: bhf.org.uk

• HDL (High-Density Lipoprotein): HDL plays a key role in removing excess cholesterol from the bloodstream and transporting it back to the liver for processing.The role of HDL in the development of atherosclerotic cardiovascular disease (ASCVD) remains a topic of debate. Historically, observational studies suggested an inverse relationship between HDL levels and cardiovascular disease, with higher HDL being considered protective. However, more recent large-scale cohort data and genetic studies have failed to confirm that higher HDL levels consistently lead to better outcomes.

• Triglycerides: A type of fat that circulates in the bloodstream and can contribute to cardiovascular disease when levels are elevated. One of the reasons why elevated triglycerides are a risk factor for cardiovascular disease is because they are indicative of high ApoB, which deliver cholesterol to the artery walls.

• ApoB (Apolipoprotein B): A key protein found in LDL and other atherogenic lipoproteins. ApoB is a better indicator of cardiovascular disease risk than LDL-cholesterol alone.

• Lipoprotein (a) (Lp(a)): A genetically influenced lipoprotein that contributes to plaque formation regardless of LDL levels.

Cholesterol and Triglycerides: Healthy Levels

Maintaining balanced cholesterol and triglyceride levels is essential for heart health, as imbalances can raise the risk of cardiovascular disease. Total cholesterol reflects the combined cholesterol content carried by all lipoproteins in the bloodstream. According to the Irish Heart Foundation, the recommended targets for blood lipids are:

• Total cholesterol: No more than 5 mmol/L

• LDL-cholesterol: No more than 3 mmol/L

• HDL-cholesterol: More than 1 mmol/L

• Triglycerides: No more than 2 mmol/L

These values serve as general guidelines, but ideal levels can vary depending on individual risk factors such as age, family history, and existing health conditions. Regular blood tests and discussions with healthcare professionals can help assess and manage cholesterol levels effectively, reducing the risk of heart disease and stroke.

The Truth About Dietary Cholesterol

For years, dietary guidelines recommended limiting cholesterol intake to 300 mg per day. For reference, one large egg contains 186mg of cholesterol. However, newer research shows that for most people, dietary cholesterol has minimal impact on blood cholesterol levels. The body tightly regulates cholesterol. When you consume more from food, the liver compensates by producing less, maintaining a balance known as homeostasis. However, individuals with genetic conditions like familial hypercholesterolemia may need to monitor cholesterol intake more closely.

Managing Cholesterol with Diet and Lifestyle

One of the most effective ways to support heart health is through a Mediterranean diet, which is rich in nutrient-dense foods and heart-healthy fats. This dietary pattern is more than just a way of eating, it also promotes lifestyle habits such as regular physical activity and smoking cessation, both of which are essential for cardiovascular health.

The Mediterranean Diet Emphasises:

• Fruits, vegetables, whole grains, and legumes as the foundation of meals.

• Healthy fats from olive oil, nuts, and seeds, which help support balanced cholesterol levels. Replace foods high in saturated fat, with dietary mono- and poly-unsaturated fat.

• Oily fish rich in omega-3 fatty acids, known for their heart-protective benefits.

• Moderate consumption of low-fat dairy.

• Limited intake of alcohol, processed or fatty cuts of meat, high sugar foods and refined carbohydrates.

Foods that modify LDL cholesterol by effect and strength of evidence. Larger circles indicate high GRADE evidence. Smaller circles indicate moderate GRADE evidence.

Source : Schoeneck, Malin et al., Nutrition, Metabolism and Cardiovascular Diseases, 2021.

How Important is Fibre Intake?

A dietary study investigated the effects of intensive cholesterol-lowering interventions using the Simian diet, which included approximately 150g of fibre per day. The results showed a remarkable 30% reduction in LDL cholesterol within just two weeks. While such a high fibre intake may not be realistic for most people, increasing fibre through a variety of fruits, vegetables, legumes, nuts, seeds, and whole grains can significantly improve cardiometabolic health. Among the many sources of fibre, oats and barley stand out for their high content of beta-glucan, a specific type of soluble fibre that has been shown to have significant cholesterol-lowering effects. Consuming at least 3g of beta-glucan daily as part of a balanced diet can help reduce cholesterol levels. Beta-glucan forms a gel in the intestines that binds to cholesterol-rich bile acids, reducing cholesterol absorption into the bloodstream. In response, the liver pulls more cholesterol from the blood to produce additional bile, ultimately lowering circulating cholesterol levels and supporting heart health.

Beyond diet, maintaining an overall healthy lifestyle including regular exercise, achieving a healthy weight, and quitting smoking, can help manage cholesterol levels and reduce the risk of heart disease. It's important to consult with a healthcare provider before implementing any new health strategies, especially when addressing conditions like elevated cholesterol. For personalised guidance, consulting a dietitian or GP can provide further insights based on your cholesterol profile and lifestyle.

Final Thoughts

Cholesterol can be a confusing subject area, awash with jargon and complex acronyms and terms. Hopefully, I have managed to remove some of this confusion, empowering you to make informed choices in relation to your heart health, which centre around healthy lifestyle choices. By taking action, you can keep your cholesterol in check, reducing your risk of heart disease and ensuring long-term cardiovascular health.

References

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• nice.org.uk/guidance/cg181#lifestyle-modifications-for-the-primary-and-secondary-prevention-of-cvd

• bhf.org.uk/informationsupport/risk-factors/high-cholesterol

• irishheart.ie