Cholesterol

What is cholesterol?#

Cholesterol is a type of fat that is part of all animal cells. It is a waxy, fat-like substance that is essential for many of the body’s metabolic processes. Cholesterol is produced by the liver and is also made by most cells in the body. It is carried around in the blood by little ‘couriers’ called lipoproteins.

We only need a small amount of blood cholesterol, because the body uses it to:

• build the structure of cell membranes
• make hormones like estrogen, testosterone and adrenal hormones
• produce bile acids, which help the body digest fat and absorb important nutrients
• help your metabolism work efficiently – for example, cholesterol is essential for your body to produce vitamin D

How cholesterol moves around the body#

Cholesterol is carried around the body by two key transport systems in the blood:

• Low-density lipoprotein (LDL) cholesterol carries most of the cholesterol that is delivered to cells. It is called the ‘bad’ cholesterol because, when its level in the bloodstream is high, it can lead to blockages that prevent blood flow to your heart.
• High-density lipoprotein (HDL) cholesterol is called the ‘good’ cholesterol because it helps remove excess cholesterol out of the cells, including cells in the arteries.

How to check your cholesterol levels#

Your doctor can check your cholesterol levels through a blood test. The blood test measures:

• total cholesterol
• HDL cholesterol
• LDL cholesterol
• triglycerides, another type of fat in the blood

As a general guide, have your cholesterol checked every 5 years from the age of 45 years, or earlier if you have a family history of high cholesterol or other risk factors. If you have a family history of high cholesterol, speak to your doctor about your heart attack risk.

There are no symptoms for high cholesterol, so a blood test is the only way to know your levels.

Safe blood cholesterol levels#

Many factors influence your cholesterol levels, and there are guidelines for target cholesterol levels in different people. As a general guide:

• Total cholesterol levels should be lower than 5.5 mmol/L if you have no other risk factors.
• If you have cardiovascular risk factors such as high blood pressure, pre-existing cardiovascular (heart) disease or diabetes, or you smoke, the aim for LDL cholesterol would be less than 2 mmol/L.

A large proportion of adults have a blood cholesterol level above 5 mmol/L, which makes high blood cholesterol a major health concern. Your doctor will talk to you about your cholesterol test results and how to lower your cholesterol and reduce your risk of heart disease.

Risk factors for high cholesterol#

There is no single cause of high cholesterol, but there are some controllable risk factors (such as smoking) and some non-controllable risk factors (such as age). Risk factors include:

• an unhealthy diet
• smoking
• lack of physical activity
• being overweight or obese
• age
• family history

Effects of high cholesterol levels#

The liver is the main processing center for cholesterol and dietary fat. When we eat animal fats, the liver transports the fat, together with cholesterol in the form of lipoproteins, into our bloodstream. Too much cholesterol circulating within LDL leads to fatty deposits developing in the arteries. This causes the vessels to narrow, and they can eventually become blocked. This can lead to heart disease, heart attacks and stroke.

Foods that contain cholesterol#

Research has shown that cholesterol in food has a relatively neutral relationship with blood cholesterol levels. For people who are not at high risk of cardiovascular disease or diabetes, and who have not previously had LDL-lowering treatment, there is no set limit to the amount of cholesterol that can be consumed in foods such as eggs and other animal products. However, if you do have these risk factors, a maximum of 7 eggs per week is advised.

Dietary tips to lower cholesterol#

A healthy diet and lifestyle can help lower your cholesterol levels over time. To follow a healthy diet:

• increase the amount and variety of fresh fruit, vegetables and wholegrain foods
• choose unflavoured and low or reduced-fat milk, yoghurt and other dairy products, or choose ‘added calcium’ alternatives (at least 100 mg/100mL); people with high cholesterol should choose reduced-fat varieties
• choose a variety of healthy proteins such as lean meat, chicken, seafood, legumes, nuts and seeds
• limit red meat to one to 3 times per week
• eat oily fish such as salmon, sardines and mackerel at least twice a week
• incorporate healthy fat choices such as nuts, seeds, avocados, olives and oils for cooking
• use herbs and spices to flavor food

How to avoid saturated fats#

Reducing foods high in saturated fats can help lower cholesterol levels. Try to minimize your intake of:

• fatty meats
• processed meats like salami and sausages
• cakes, biscuits and pastries
• snack foods like chips
• most takeaway foods, especially deep-fried foods

Foods that may lower cholesterol levels#

• LDL cholesterol can be lowered by polyunsaturated oils (for example, sunflower or safflower oil).
• Eating oats and legumes can lower LDL cholesterol by around 5%.
• Food components like saponins (found in chickpeas, alfalfa sprouts and other foods) and sulfur compounds (like allicin, found in garlic and onions) may also help lower cholesterol levels.
• Plant sterols can lower cholesterol levels and are found naturally in plant foods, including sunflower and canola seeds, vegetable oils and, in smaller amounts, in nuts, legumes, cereals, fruit and vegetables. Some margarines, milks and cereals have concentrated plant sterols added to them. The recommended amount is 2 to 3 g per day; consuming more than this does not cause harm, but provides no additional benefit.

Lifestyle tips to cut cholesterol#

Changing some of your lifestyle habits may also help reduce your cholesterol and triglyceride levels:

• Limit alcohol. Reduce your alcohol intake to no more than one or 2 drinks a day, and avoid binge drinking. This may help lower your triglyceride levels.
• Don’t smoke. Smoking increases the ability of LDL cholesterol to get into artery cells and cause damage.
• Exercise regularly – for example, at least 30 minutes of brisk walking daily. Exercise increases HDL levels while reducing LDL and triglyceride levels.
• Reduce excess body fat. Being overweight can raise LDL levels.
• Manage your blood sugar within your target range if you have diabetes. High blood sugars are linked to an increased risk of atherosclerosis (‘hardening of the arteries’), heart attacks and strokes.

Medication may be needed for high cholesterol#

For some people, diet and lifestyle changes are not enough to lower cholesterol. High blood cholesterol levels often have a genetic component. Some people inherit altered genes that cause high cholesterol, and this cannot usually be changed sufficiently by lifestyle or diet alone.

If you are at risk of coronary heart disease and your LDL cholesterol level doesn’t drop after dietary and lifestyle changes, your doctor may recommend medications to reduce your blood LDL levels. Statins are the most common medication used to lower blood cholesterol. Statins slow the amount of cholesterol made in your liver, so the liver uses the cholesterol already in your blood instead, lowering the level of LDL cholesterol.

If statins do not lower your cholesterol enough, you may need additional medicines. Some people get muscle aches from statins. Diet and exercise remain important even if you are taking medication. Your doctor may also refer you to a specialist who treats cardiovascular disease.

Key points#

• Your body needs some cholesterol, but high LDL (‘bad’) cholesterol raises your risk of heart disease.
• There are no symptoms for high cholesterol, so a blood test is the only way to know your levels.
• Total cholesterol should generally be lower than 5.5 mmol/L if you have no other risk factors.
• A healthy diet, regular exercise, not smoking and limiting alcohol can all help lower cholesterol.
• Some people also need medication, such as statins, but diet and exercise still matter.

Where to get help and trusted information#

For evidence-based global health guidance, see Source: World Health Organization (WHO).