Cholesterol is a type of fat that is essential for many of the body’s metabolic processes, including the production of hormones, bile and vitamin D.
It is produced by the liver and also made by most cells in the body. It is carried around in the blood by little ‘couriers’ called lipoproteins. We need a small amount of blood cholesterol for its various functions.
Cholesterol is carried around the body by 2 key transport systems in the blood, which include: Low-density lipoprotein (LDL) 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.
Many factors influence your cholesterol levels. 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 levels would be less than 2 mmol/L.
Too much cholesterol 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 and stroke.
The updated guidance centres on lowering low-density lipoprotein (LDL) cholesterol, commonly known as bad cholesterol, along with other blood fats such as lipoprotein. It also highlights the need for earlier screening, particularly for people with a family history of heart disease, and calls for more individualised risk assessments based on factors like existing health conditions.
“We know that lower LDL cholesterol levels are better when it comes to reducing the risk of heart attacks, strokes and congestive heart failure,” says Roger S. Blumenthal, chair of the guideline writing committee and director of the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease.
“We also know that bringing elevated lipids and blood pressure down in young adults supports optimal heart and vascular health throughout a person’s life.”
The update arrives as research shows that about 1 in 4 adults has elevated LDL cholesterol (LDL-C), a major contributor to atherosclerosis (the narrowing or hardening of the arteries). When certain lipids build up, they can form plaque inside artery walls. This plaque can restrict blood flow, and under certain conditions, it may rupture and trigger a heart attack or stroke or require urgent medical treatment to restore circulation.
Despite these risks, the core advice for maintaining heart health remains unchanged. Experts continue to stress the importance of a balanced diet, regular physical activity, avoiding tobacco, getting enough sleep, and maintaining a healthy weight. According to Blumenthal, roughly 80% to 90% of cardiovascular disease is linked, at least in part, to factors people can modify, making lifestyle changes a critical first step.
A key shift in the new guideline is the push for screening at younger ages and a broader look at personal risk. Doctors are encouraged to consider family history of atherosclerosis, underlying conditions such as rheumatoid arthritis, and life events like early menopause or pregnancy complications, including preeclampsia or gestational diabetes, when evaluating risk and planning treatment.
Another major update is the introduction of a new tool for estimating 10- and 30-year risk of heart attack and stroke. The previous model focused mainly on 10-year risk for adults age 40 and older and relied on basic factors such as age, cholesterol levels, and blood pressure.
The new calculator, Predicting Risk of Cardiovascular Disease EVENTs (PREVENT), includes additional measures such as blood sugar and kidney function. It is designed for use starting at age 30.
