# LDL Cholesterol
URL: https://genohealth.app/biomarkers/ldl-cholesterol
Units: mg/dL
Functional optimal: < 100 mg/dL (general); < 70 mg/dL (high CV risk)
Clinical reference: < 130 mg/dL (borderline above)
Evidence: Strong evidence
Last reviewed: 2025-06-30

## Summary
LDL cholesterol is the most widely measured lipid risk marker — but the right target depends on your genetics, your other risk factors, and increasingly, on your ApoB.

## What it is
Low-density lipoprotein (LDL) cholesterol is the cholesterol carried by LDL particles. It is the most established and most studied modifiable risk factor for atherosclerotic cardiovascular disease.

## Why it matters
Decades of randomized evidence show that lowering LDL-C reduces heart attacks and strokes. Every 39 mg/dL (1 mmol/L) reduction in LDL-C corresponds to roughly a 22% reduction in major vascular events per year of treatment.

## Causes of high
- Genetic — APOE ε4, familial hypercholesterolemia (LDLR, APOB, PCSK9)
- Diet high in saturated fat and trans fat
- Hypothyroidism, nephrotic syndrome, cholestasis
- Pregnancy (transient)
- Some medications (thiazides, glucocorticoids, certain antipsychotics)

## Causes of low
- Genetic hypobetalipoproteinemia
- Severe liver disease, malabsorption
- Hyperthyroidism
- Statin, ezetimibe, or PCSK9 inhibitor therapy

## Lifestyle
- Regular aerobic exercise lowers LDL modestly and improves particle quality
- Weight loss in overweight adults
- Stop smoking — improves the full lipid profile

## Nutrition
- Replace saturated fat with mono- and polyunsaturated fats (Mediterranean pattern)
- Soluble fiber 25-35 g/day (oats, beans, psyllium)
- Plant sterols/stanols 2 g/day lower LDL by ~10%
- Limit ultra-processed food and added sugars

## Testing notes
Fasting is no longer strictly required for routine lipid panels. Re-test 8-12 weeks after meaningful changes. Pair with ApoB when available for a clearer picture.

## Related (knowledge graph)

### Biomarkers
- ApoB (/biomarkers/apob): 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 ε4 carriers absorb saturated fat efficiently and run higher LDL; ε2 carriers typically run lower LDL but have other lipid quirks. [Strong evidence]

### Conditions
- CV Risk (/conditions/cardiovascular-disease): Lowering LDL-C reduces major cardiovascular events proportionally to the reduction achieved. [Strong evidence]

## FAQ
**Q: What LDL level should I aim for?**
A: For most healthy adults, under 100 mg/dL is a reasonable target. For people with existing heart disease, diabetes, or strong family history, many specialists now target under 70 mg/dL — and under 55 mg/dL for very high risk.

**Q: Does APOE genotype change my LDL target?**
A: Yes, in practice. APOE ε4 carriers tend to absorb dietary saturated fat more efficiently and run higher LDL, so many clinicians treat ε4 carriers more aggressively. APOE ε2 carriers often run lower LDL but can have different lipid challenges.

**Q: Can lifestyle alone fix high LDL?**
A: For mild-to-moderate elevations, yes — diet, exercise, weight loss, and stopping smoking can lower LDL meaningfully. For familial hypercholesterolemia or very high LDL, medication is usually required regardless of lifestyle.

## Citations
- Cholesterol Treatment Trialists' Collaboration, Lancet 2010 (PMID 21067804): Each 1 mmol/L reduction in LDL-C reduces major vascular events ~22% per year of treatment.
- Mahley & Rall, Annu Rev Genomics 2000 (PMID 11701624): APOE genotype is the single strongest common genetic determinant of plasma LDL-C levels.

Disclaimer: Informational only — not medical advice.