What your cholesterol and ApoB levels say about your health

Cholesterol is a fatty substance which, despite having a bad name, is actually vital for our existence. Practically every single cell in our body synthesises cholesterol. It is a primary component of all cell membranes and is required for the synthesis of vitamins, hormones and bile acids. As it is a fatty substance it cannot be transported simply in our blood, like for example glucose or electrolytes, because blood is a water-based. Therefore, when cholesterol molecules need to be transported around the body within the blood they must be carried within special vehicles called lipoproteins. 

There are various types of lipoproteins but the two main classes are high density lipoproteins (HDLs) and low density lipoproteins (LDLs). Each LDL carries a single particle known as apolipoprotein B (apoB) and this is where cholesterol’s notoriety stems from. ApoB is a known cause of atherosclerotic cardiovascular disease (ASCVD) - the best test for your ‘bad cholesterol’ is to test your ApoB levels. 

Atherosclerosis is caused by plaque buildup in artery walls and causes conditions including heart attacks, strokes and aneurysms. It is by far the leading cause of death worldwide - killing some 18 million people every year. Like many chronic diseases it develops over a long period of time. Its biggest drivers are apoB, insulin resistance, high blood pressure and smoking.

ApoB is the so called ‘bad cholesterol’ and is a causative factor of ASCVD. This is why it is important to regularly check apoB levels and seek medical advice on how to keep our levels below a certain threshold throughout our lives. 

The problem with apoB is that when it is above a certain level in our blood, it enters artery walls to form plaques which may cause narrowing of arteries or blood clot formation. As apoB levels in the blood increase so too does disease progression. This is also true of duration to apoB exposure, which is why we should aim to consistently have low levels of apoB throughout our lives.

This measure is not typically part of a standard lipid profile which usually includes: total cholesterol, LDL-C, HDL-C and triglycerides. LDL-C, or LDL cholesterol, is a measure of how much cholesterol is carried by these harmful LDL particles. They therefore give an indication on the number of LDL particles in circulation and therefore an approximation of the amount of apoB since each LDL particle carries one apoB. There are other particles in the blood containing apoB, such as VLDLs and chylomicrons, however these typically make up only 5-10% of all apoB lipoproteins.

High levels of LDL particles are often caused by lifestyle habits such as unhealthy eating patterns. However, genetics may also strongly influence these levels. For example people with familial hypercholesterolaemia have a genetic defect which reduces rate of LDL removal from blood. 

So what can we do to decrease the harmful cholesterol in our blood and reduce our risk of disease? A combination of lifestyle changes and pharmacological drugs help achieve control of elevated LDL levels. Diet directly influences blood cholesterol levels. Managing insulin resistance through carbohydrate restriction is the most effective dietary tool. Refined and starchy carbohydrates such as white rice, white bread, white pasta and potatoes should be avoided and replaced with wholegrains, fruits and vegetables. Reducing or avoiding saturated fats such as those found in full fat dairy, red/processed meat and coconut oil and replacing with lean protein, nuts, seeds, olive oil and fatty fish. Trans fats such as that found in margarine and deep fried foods should be avoided altogether. 

In addition, being physically active, getting enough exercise, maintaining a healthy weight, stopping smoking and limiting alcohol consumption may all help reduce elevated LDL. Certain supplements have also proven to be effective at lowering LDL. Red yeast rice is one such supplement - its main active compound is identical to a particular statin and its effects may be comparable. However, as discussed previously supplements are not rigorously regulated in the same way as drugs and caution is advised before consumption.

From a pharmacological point of view, treatment with statins is highly effective at lowering LDL levels and therefore reducing the risk of a major cardiac event. These drugs are the first line of treatment as they are effective and safe in the majority of people - being on the correct dose and particular statin as prescribed by your doctor typically resolves any side effects. Currently, statins are typically prescribed only when LDL-C levels greatly exceed the amount of LDL-C required for our bodies to function optimally. However, as discussed above, the progression of ASCVD is dependent on both level and duration of LDL. Therefore there may be substantial benefits to starting statins below ‘typical’ thresholds.

There are also various non-statin therapies which may be prescribed such as PCSK9 inhibitors and Bempedoic acid. These may be given combined with a statin, if for example statins and lifestyle changes aren’t effective enough, or instead of a statin, in the case that, for example, significant statin side-effects. 

Treatment plans for managing levels of LDL are very individual and require close management and monitoring depending on your personal risk and family history. ASCVD is one of the few chronic diseases for which we have a causative factor - apoB-containing lipoproteins circulating in our blood stream. Standard lipid tests often give a good indication of ASCVD risk via the LDL-C measurement, though an ApoB test would be the gold standard. 

Having an overall healthy lifestyle is important - diet has the largest effect. Getting your LDL and/ or your apoB levels tested regularly is vital. The longer your arteries are exposed to unhealthy levels of apoB the higher your risk. So the earlier you determine undesirable levels of apoB the better chance you have of avoiding ASCVD through the correct treatment plan.

If you would like to test your personal risk factors for developing chronic diseases of ageing, and find out if weight loss drugs are indicated for you, find out more about the Longevity Annual health check and download the longevity doctor guide to healthy living.