What causes high cholesterol in most people? 

In the UK, high cholesterol is most commonly caused by a combination of lifestyle choices, particularly a diet high in saturated fats and a lack of regular physical activity. While the liver produces most of the cholesterol the body needs, certain factors can trigger it to produce too much or slow down the process of clearing it from the blood. For a significant number of people, age, genetics, and underlying health conditions also play a critical role in how their bodies manage blood fats. 

Cholesterol is a vital fatty substance used to build cell membranes and hormones, but having too much in the blood can lead to serious health complications. For the majority of the population, high cholesterol is not the result of a single factor but rather a cumulative effect of several ‘controllable’ lifestyle habits. Understanding these triggers is the first step toward effective management and reducing the long-term risk of heart disease and stroke. 

What We’ll Discuss in This Article 

• The impact of dietary saturated and trans fats on liver function. 

• How a lack of physical activity influences ‘good’ and ‘bad’ cholesterol levels. 

• The role of smoking and alcohol in damaging vascular health. 

• Inherited conditions like Familial Hypercholesterolaemia (FH). 

• Medical triggers such as the menopause and underactive thyroid. 

• Why age and ethnicity are significant non-modifiable risk factors. 

Lifestyle causes: Diet and activity 

The single most common cause of high cholesterol in the UK is a diet high in saturated fats. Saturated fats are found in foods like fatty meats, butter, ghee, lard, and full-fat dairy. When you consume these fats, they signal the liver to increase the production of Low-Density Lipoprotein (LDL) cholesterol and simultaneously slow down the rate at which LDL is removed from the bloodstream. 

Inactivity also plays a major role. Regular aerobic exercise helps to boost the levels of High-Density Lipoprotein (HDL), which acts as a ‘scavenger’ to remove bad cholesterol from the arteries. Without enough movement, HDL levels can drop, allowing LDL to build up more easily. The British Dietetic Association (2024) notes that most people in the UK eat 20% more saturated fat than the recommended daily limit, which for women is 20g and for men is 30g. 

The impact of smoking and alcohol 

Smoking is a powerful trigger for cholesterol problems because a chemical found in cigarettes called acrolein prevents HDL from taking cholesterol from the artery walls back to the liver. This makes the existing LDL in the blood ‘stickier’, increasing the rate at which arterial plaques form. 

Alcohol consumption, particularly when excessive, can raise both total cholesterol and triglycerides. Because the liver prioritises the breakdown of alcohol, its ability to process and clear other fats from the blood is temporarily impaired. According to NHS guidelines (2025), staying within the limit of 14 units per week and having several drink-free days can help maintain a healthier lipid profile. 

Genetic factors and age 

For some people, high cholesterol is not caused by lifestyle but is ‘in the genes’. The most notable condition is Familial Hypercholesterolaemia (FH), which affects approximately 1 in 250 people in the UK. People with FH are born with a genetic mutation that makes their liver unable to clear LDL cholesterol effectively, leading to very high levels even in those who are thin and eat a healthy diet. 

As we get older, our cholesterol levels naturally tend to rise. This is partly because the liver becomes less efficient at clearing LDL from the blood as we age. For women, the menopause is a major biological trigger; the drop in oestrogen which has a protective effect on cholesterol often leads to a sharp increase in LDL and a decrease in HDL. 

Cause Category	Specific Factor	Clinical Impact
Dietary	Saturated and Trans Fats	Increases LDL production and slows clearance.
Habitual	Smoking and Inactivity	Lowers protective HDL and damages artery walls.
Genetic	Familial Hypercholesterolaemia	Causes exceptionally high LDL from birth.
Medical	Menopause / Hypothyroidism	Hormonal shifts that disrupt lipid metabolism.

Secondary medical causes 

High cholesterol can also be a ‘secondary’ effect of other health issues or medications. This means that the raised lipids are a symptom of an underlying problem that needs to be addressed. 

Common secondary triggers include: 

• Underactive thyroid (hypothyroidism): Low levels of thyroid hormone slow down the body’s metabolism, including the breakdown of fats. 

• Type 2 Diabetes: High blood sugar can damage the lining of the arteries and lead to a specific pattern of high triglycerides and low HDL. 

• Kidney and Liver Disease: These organs are vital for processing and excreting fats; if they are not functioning correctly, cholesterol levels can rise. 

• Medications: Certain medicines, such as steroids, diuretics, and some blood pressure drugs (beta-blockers), can occasionally raise lipid levels as a side effect. 

To Summarise 

High cholesterol in most people is caused by a combination of high saturated fat intake, physical inactivity, and the natural effects of ageing. However, for a significant minority, genetic conditions like FH or underlying medical issues like an underactive thyroid are the primary drivers. Because these causes often overlap, the NHS uses the QRISK3 tool to assess overall risk and determine whether lifestyle changes alone or medical treatments like statins are required. 

‘If you experience severe, sudden, or worsening symptoms, such as sudden chest pain or difficulty breathing, call 999 immediately.’ 

You may find our free BMI Calculator helpful for understanding how your weight and body composition may be impacting your cholesterol risk. 

Authority Snapshot (E-E-A-T Block) 

This article was written by the MyPatientAdvice Medical Content Team and reviewed by Dr. Rebecca Fernandez to ensure clinical accuracy and adherence to 2026 UK medical standards. Dr. Fernandez is a UK-trained physician with an MBBS and extensive experience in cardiology, internal medicine, and emergency medicine. This guide provides evidence-based information on the multi-faceted causes of high cholesterol to help the public manage their heart health effectively.