Unless you’re a lipids researcher or a fan of health podcasts, you’ll be forgiven for not knowing what Apolipoprotein B-100 is. The protein (ApoB to its friends) is created in the liver. It helps shift dietary fat and cholesterol around the body, and bind them to cells where they can be used, stored or removed.
But it’s also something of a celebrity: the focus of online chat, at-home health tests and biomedical research. All because measuring ApoB is a highly accurate way of predicting a person’s risk of cardiovascular disease – more so than traditional cholesterol tests.
A 2021 paper in The Lancet Health Longevity said ApoB was emerging as the “crucial lipoprotein trait” in working out how cholesterol contributes to your risk of a broken heart. Researchers concluded that “higher ApoB shortens lifespan, increases risks of heart disease, stroke … and diabetes.”
Right now, measuring LDL cholesterol is one of the standard ways to test somebody’s cardiovascular risk. LDL is ‘the bad one’, but it’s not the only bad one. LDL cholesterol tests, while accurate, don’t always give us the full picture. A person could return a low LDL test, but the picture inside their arteries could still be concerning.
What’s interesting about ApoB is that there’s a single molecule of it attached to all lipoproteins that amass in our arteries. That includes LDL, but also VLDL (very-low-density lipoprotein), IDL (intermediate-density lipoprotein) and LP(a), a very sticky lipoprotein, which may be more likely to cause blockages.
“ApoB is attached to these four important lipid entities,” says Dr Catherine Lunken, a consultant at University College London Hospitals and an expert in lipid disorders. “So it’s a direct measure of the number of circulating atherogenic lipoproteins. It’s a more accurate indicator of cardiovascular risk.”
Another paper, this one from 2022 in the journal Nutrition, Metabolism and Cardiovascular Disease, tried to tease out the difference between regular cholesterol tests and ApoB tests. Often, the two deliver similar results. But in some cases, the same person who scores low on LDL, scores high on ApoB – and those people are still at an increased risk of cardiovascular problems.
“You have people with heart attacks with so-called ‘normal’ LDL,” says Lunken. “So ApoB may be part of what people aren’t looking at.”
ApoB tests aren’t routinely offered on the NHS. Lunken suspects they will be one day, but they’re considerably more expensive than cholesterol tests. And as the science is still emerging on ApoB, some clinicians may not even understand it.
That hasn’t prevented businesses from selling ApoB tests direct to consumers. A quick internet search turns up plenty of options, many promising results in a few days and advice on how to interpret them. They cost between £50-£180. Another option is visiting a private clinic that’ll test for ApoB specifically or as part of a wider health check.
Whether you actually need one or not is the question. Lunken says that ApoB scores are more insightful for young people. It tells them about their long-term risk, but also if there’s a more imminent danger of a heart attack. For that reason, the tests might appeal to those who take a proactive and preventative approach to their health.
The flip side is whether private tests like these exploit the ‘worried well’ and contribute to health anxiety, especially as researchers are still working to understand the correlation between ApoB scores and heart health.
It’s not known, for example, what the best way to reduce your ApoB score is, but the lifestyle advice generally follows other heart health recommendations: eat a Mediterranean diet, lose weight, don’t smoke or drink too much.
Lunken says her heart sank when she discovered that DIY ApoB tests were becoming popular, but she also says that ApoB tests are the best predictor of long-term cardiovascular risk.
“I wouldn’t even expect GPs to know about ApoB,” she says. “It’s a good test. [But] my worry is that the people who have it, don’t yet have the support to follow up with.”
About our expert
Dr Catherine Lunken is a consultant at University College London Hospitals. She specialises in researching diabetes and lipid disorders, alongside cardiovascular risk prevention.
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