Is ApoB more important than regular cholesterol (LDL)?

ApoB is a protein found on all so-called 'bad' fat particles in the blood, such as LDL, VLDL and IDL. Each of those particles carries exactly one ApoB molecule. Measuring ApoB therefore provides a direct count of the total number of risk particles in your blood, whereas LDL cholesterol only measures the amount of fat inside those particles. A systematic review of 15 studies involving a total of 593,354 participants showed that ApoB was a better predictor of cardiovascular disease than LDL cholesterol in all 9 available comparisons. The researchers conclude that LDL cholesterol is not a good substitute for ApoB in clinical practice (PMID 40681368).

A large Danish study of 95,108 people (non-statin users) confirmed this in a different way: the higher the 'excess ApoB' -- that is, the information ApoB adds on top of what LDL cholesterol already predicts -- the higher the risk of heart attack. This held true for both men and women and across the full range of LDL values. ApoB therefore contains information that LDL cholesterol simply misses (PMID 38839200).

The comparison with non-HDL cholesterol (already a somewhat broader measure than plain LDL) is less clear-cut. In 7 of 9 comparisons in the same systematic review, ApoB also outperformed non-HDL cholesterol, but in one study non-HDL was superior and in one study they were equivalent (PMID 40681368). ApoB therefore appears to be the most informative measure, but its advantage over non-HDL is smaller than its advantage over LDL.

There are also limits to what ApoB tells us. An analysis of 17,532 people without known cardiovascular disease showed that elevated remnant cholesterol -- the cholesterol in triglyceride-rich particles -- was associated with a 65% higher risk of a cardiovascular event, even after statistically adjusting for both LDL and ApoB. ApoB therefore does not fully capture this additional risk (PMID 34293083). In addition, a large British cohort study (271,760 participants) suggests that the composition of LDL particles -- small and dense LDL versus large and buoyant LDL -- is also relevant alongside ApoB (PMID 40808652).

Despite all this evidence, ApoB has still not been widely adopted in everyday clinical practice. An important reason is the absence of clear, consistent ApoB target values in guidelines, whereas such targets do exist for LDL cholesterol (PMID 38950110). Finally, it is worth knowing that lifestyle also influences ApoB: a meta-analysis of 58 randomised studies showed that oat beta-glucan (the fibre in oatmeal, approximately 3.5 g per day) significantly lowers ApoB, although the reduction is modest (on average 0.03 g/l) (PMID 27724985).