# ApoB (Apolipoprotein B)
URL: https://genohealth.app/biomarkers/apob
Units: mg/dL
Functional optimal: < 80 mg/dL (general); < 60 mg/dL (high CV risk)
Clinical reference: < 130 mg/dL (standard lab reference)
Evidence: Strong evidence
Last reviewed: 2025-06-30

## Summary
ApoB counts the number of atherogenic particles circulating in your blood — increasingly recognized as a more accurate marker of cardiovascular risk than LDL cholesterol alone.

## What it is
Apolipoprotein B is the structural protein found on every atherogenic lipoprotein particle (LDL, VLDL, IDL, Lp(a)). Because each of these particles carries exactly one ApoB molecule, measuring ApoB directly counts the number of particles capable of depositing cholesterol in artery walls.

## Why it matters
Cardiovascular disease is driven by the number of atherogenic particles, not just the cholesterol they carry. Two people can have the same LDL-C but very different ApoB — and the one with higher ApoB carries higher risk. Major lipid societies (NLA, EAS, CCS) now treat ApoB as a primary or co-primary target alongside LDL-C.

## Causes of high
- Familial hypercholesterolemia (LDLR, APOB, PCSK9 variants)
- APOE ε4 carriers tend toward higher LDL/ApoB
- Diet high in saturated fat and refined carbohydrates
- Insulin resistance and metabolic syndrome
- Hypothyroidism
- Sedentary lifestyle, central obesity

## Causes of low
- Genetic hypobetalipoproteinemia (rare)
- Severe liver dysfunction
- Malabsorption or undernutrition
- Statin or PCSK9-inhibitor therapy

## Lifestyle
- Aerobic exercise 150+ minutes/week reduces particle count
- Weight loss of 5-10% meaningfully lowers ApoB in overweight adults
- Smoking cessation improves the entire lipid profile

## Nutrition
- Mediterranean pattern — extra-virgin olive oil, fatty fish, legumes, leafy greens
- Soluble fiber 25-35 g/day (oats, psyllium, beans) lowers LDL particles
- Replace saturated fat with mono- and polyunsaturated fats
- Limit refined sugar and ultra-processed carbohydrates

## Testing notes
Standard blood draw — fasting is not strictly required for ApoB. Re-test 8-12 weeks after any meaningful diet, exercise, or medication change.

## Related (knowledge graph)

### Biomarkers
- LDL-C (/biomarkers/ldl-cholesterol): ApoB counts atherogenic particles; LDL-C measures the cholesterol they carry. They correlate but can disagree — when they do, ApoB usually wins on risk. [Strong evidence]

### Genes
- APOE (/genes/apoe): APOE genotype is one of the strongest common genetic determinants of circulating ApoB-bearing particles; ε4 carriers tend to higher ApoB. [Strong evidence]

### Conditions
- CV Risk (/conditions/cardiovascular-disease): ApoB is the most discriminating single lipid marker for atherosclerotic CV risk. [Strong evidence]

## FAQ
**Q: Why is ApoB sometimes better than LDL cholesterol?**
A: LDL-C measures the cholesterol mass inside LDL particles, but small dense LDL particles carry less cholesterol per particle — so two people can have identical LDL-C with very different particle counts. ApoB counts the particles directly, which is what physically interacts with the artery wall.

**Q: What is a good ApoB level?**
A: For general population goals, under 80 mg/dL is reasonable. For people with established cardiovascular disease, diabetes, or high genetic risk, under 60 mg/dL is the target most lipid specialists recommend.

**Q: Do I need to fast for an ApoB test?**
A: No. Unlike triglycerides, ApoB is stable across fed and fasted states, which is part of why it has become the preferred marker.

**Q: How quickly can ApoB change?**
A: Diet and exercise changes start moving ApoB within weeks; meaningful, sustained changes are typically visible at 8-12 weeks. Statins and PCSK9 inhibitors lower ApoB substantially within 4-8 weeks.

## Citations
- Sniderman et al., JAMA Cardiology 2019 (PMID 31389978): ApoB is a superior marker of CV risk compared with LDL-C and non-HDL-C in head-to-head analyses.
- ESC/EAS Guidelines for Dyslipidaemias 2019: ApoB recommended as an alternative or co-primary measurement to LDL-C for risk assessment.

Disclaimer: Informational only — not medical advice.