Cholesterol is one of the most talked-about health markers, yet it remains widely misunderstood. When most people hear the word "cholesterol," they immediately think of something harmful that should be avoided at all costs. However, the reality is far more nuanced. Cholesterol is actually essential for life – your body needs it to build cell membranes, produce hormones, and create vitamin D. The key lies in understanding the different types of cholesterol and maintaining the right balance.

What Exactly Is Cholesterol?

Cholesterol is a waxy, fat-like substance that is found in every cell of your body. Your liver produces most of the cholesterol your body needs, but you also obtain cholesterol from animal-based foods such as meat, eggs, and dairy products. Because cholesterol cannot dissolve in blood, it needs to be transported through your bloodstream by carriers called lipoproteins. The two main types of lipoproteins are LDL and HDL, and understanding the difference between them is crucial for managing your heart health.

LDL Cholesterol: The "Bad" Cholesterol

Low-Density Lipoprotein (LDL) is often referred to as "bad" cholesterol, although this label is somewhat oversimplified. LDL carries cholesterol from your liver to the cells throughout your body. This is a necessary function – cells need cholesterol to maintain their structure and produce certain hormones.

The problem arises when there is too much LDL cholesterol in your bloodstream. When LDL levels are elevated, the excess cholesterol can accumulate in the walls of your arteries, forming a thick, hard deposit called plaque. This process, known as atherosclerosis, causes your arteries to narrow and become less flexible. Over time, this can restrict blood flow to vital organs, including your heart and brain.

If a plaque ruptures, it can trigger a blood clot that may block blood flow entirely, potentially causing a heart attack or stroke. This is why keeping LDL levels within a healthy range is so important for cardiovascular health.

What are healthy LDL levels?

Optimal: Less than 2.6 mmol/L (100 mg/dL)

Near optimal: 2.6-3.3 mmol/L (100-129 mg/dL)

Borderline high: 3.4-4.1 mmol/L (130-159 mg/dL)

High: 4.1-4.9 mmol/L (160-189 mg/dL)

Very high: Above 4.9 mmol/L (190 mg/dL and above)

HDL Cholesterol: The "Good" Cholesterol

High-Density Lipoprotein (HDL) is known as "good" cholesterol because it performs a protective function. HDL acts like a cleanup crew in your bloodstream, picking up excess cholesterol from your arteries and transporting it back to your liver, where it can be broken down and removed from your body. This process is sometimes called "reverse cholesterol transport."

Higher levels of HDL cholesterol are associated with a lower risk of heart disease. HDL not only removes excess cholesterol but also has anti-inflammatory and antioxidant properties that help protect the lining of your blood vessels.

What are healthy HDL levels?

Low (increased risk): Less than 1.0 mmol/L (40 mg/dL) for men, less than 1.3 mmol/L (50 mg/dL) for women

Desirable: 1.0-1.5 mmol/L (40-59 mg/dL)

Optimal (protective): 1.6 mmol/L (60 mg/dL) and above

Triglycerides: The Third Piece of the Puzzle

While not technically cholesterol, triglycerides are another type of fat found in your blood that plays an important role in heart health. When you eat, your body converts calories it doesn't need immediately into triglycerides, which are stored in fat cells. Between meals, hormones release triglycerides for energy.

High triglyceride levels, particularly when combined with high LDL or low HDL cholesterol, can contribute to the hardening and narrowing of artery walls. Elevated triglycerides are often associated with other conditions that increase heart disease risk, such as obesity, metabolic syndrome, and type 2 diabetes.

What are healthy triglyceride levels?

Normal: Less than 1.7 mmol/L (150 mg/dL)

Borderline high: 1.7-2.2 mmol/L (150-199 mg/dL)

High: 2.3-5.6 mmol/L (200-499 mg/dL)

Very high: Above 5.6 mmol/L (500 mg/dL and above)

Total Cholesterol: The Big Picture

Your total cholesterol number is the sum of your LDL, HDL, and 20% of your triglyceride level. While total cholesterol gives a general overview, it doesn't tell the whole story. Someone with high total cholesterol might actually have a healthy profile if their HDL is very high. Conversely, someone with "normal" total cholesterol could still be at risk if their LDL is high and HDL is low.

This is why a comprehensive lipid profile that breaks down the different components is more valuable than knowing your total cholesterol alone.

What Causes High Cholesterol?

Several factors can influence your cholesterol levels, some within your control and others not:

Factors you can control:

Diet - Foods high in saturated fats (fatty meats, full-fat dairy, fried foods) and trans fats (some processed foods, baked goods) can raise LDL cholesterol. Dietary cholesterol from animal products has less impact than previously thought, but still plays a role for some people.

Physical activity - Regular exercise helps raise HDL cholesterol while lowering LDL and triglycerides. Aim for at least 150 minutes of moderate aerobic activity per week.

Weight - Being overweight or obese tends to raise LDL and triglycerides while lowering HDL. Even modest weight loss can help improve your cholesterol profile.

Smoking - Smoking damages the walls of your blood vessels, making them more prone to accumulating fatty deposits. It also lowers HDL cholesterol.

Alcohol consumption - While moderate alcohol intake may slightly raise HDL, excessive drinking raises triglycerides and can lead to other health problems.

Factors beyond your control:

Age - Cholesterol levels naturally rise as you get older. Before menopause, women tend to have lower total cholesterol than men of the same age. After menopause, women's LDL levels often rise.

Genetics - Your genes partly determine how much cholesterol your body makes. Familial hypercholesterolaemia is an inherited condition that causes very high LDL levels from a young age.

Sex - Men generally have higher LDL and lower HDL levels than premenopausal women.

The Importance of Cholesterol Testing

High cholesterol typically has no symptoms. You can have dangerously elevated levels for years without knowing it. This is why regular testing is so important – it's the only way to know your numbers.

A lipid profile (also called a lipid panel or cholesterol test) measures:

Total cholesterol

LDL cholesterol

HDL cholesterol

Triglycerides

Some advanced tests also measure the size and number of LDL particles, which can provide additional insight into cardiovascular risk.

How to Prepare for a Cholesterol Test

For the most accurate results, you should typically fast for 9-12 hours before your blood test. This means no food or drinks other than water. Fasting is particularly important for getting accurate triglyceride readings, as these levels rise significantly after eating.

At Private Blood Tests London, we offer comprehensive lipid profile testing at our South Kensington clinic. The blood draw takes just a few minutes, and you can eat and drink normally afterwards.

Improving Your Cholesterol Naturally

If your cholesterol levels aren't optimal, lifestyle changes can make a significant difference:

Dietary changes:

Reduce saturated fat intake (found in red meat, full-fat dairy, and tropical oils)

Eliminate trans fats (check labels for "partially hydrogenated oils")

Eat more omega-3 fatty acids (found in fatty fish like salmon, mackerel, and sardines)

Increase soluble fibre intake (oats, beans, lentils, fruits, vegetables)

Add plant sterols and stanols (found in fortified foods)

Lifestyle modifications:

Exercise regularly – aim for at least 30 minutes most days

Maintain a healthy weight

Stop smoking

Limit alcohol consumption

When to Seek Medical Advice

We provide raw cholesterol data through our lipid profile tests. We do not offer interpretation or medical advice. If your results show elevated cholesterol or you have concerns about your cardiovascular health, we recommend sharing your results with your GP or healthcare provider. They can interpret your results in the context of your overall health, family history, and other risk factors, and advise on any treatment if needed.

The Bottom Line

Understanding your cholesterol is an important step in taking control of your heart health. Rather than fearing cholesterol entirely, focus on maintaining the right balance – keeping LDL and triglycerides low while supporting healthy HDL levels. Regular testing, combined with heart-healthy lifestyle choices, can help you maintain optimal cardiovascular health for years to come.

Good vs Bad Cholesterol: What You Need to Know