Hypertriglyceridemia — The Starting Point
Fasting triglycerides climb when the liver makes more VLDL than the body clears.
- <150: Normal TG threshold (mg/dL, ATP III cutoff)
- ≥500: Very high TG (mg/dL, pancreatitis risk)
- ~25%: US adults w/ high TG (NHANES estimate)
- ~90%: Hepatic VLDL source (of plasma triglyceride)
What is hypertriglyceridemia
Fasting triglycerides above 150 mg/dL define hypertriglyceridemia.
Liver as triglyceride source
Liver packages fatty acids into VLDL triglyceride particles.
Severe cases exceed 500 mg/dL, risking acute pancreatitis.
Cardiovascular risk link
Very high triglycerides raise pancreatitis and cardiovascular risk.
EPA/DHA Supplementation Starts
Marine omega-3 fatty acids enter the bloodstream at a dose-dependent rate.
- 2–4: Effective EPA+DHA dose (g/day, clinical range)
- 4 g: Icosapent ethyl (EPA) (per day, REDUCE-IT dose)
- ~37 h: Plasma EPA half-life (approximate)
- 2–4: Onset of TG effect (weeks, initial response)
EPA and DHA sources
Marine fish oil supplies eicosapentaenoic and docosahexaenoic acids.
Prescription vs OTC omega-3
Prescription formulations deliver higher, purer EPA/DHA doses.
Doses below 2 g/day rarely lower triglycerides meaningfully.
Dose determines effect size
Larger daily dose produces greater triglyceride reduction.
Hepatic Triglyceride Synthesis Is Reduced
Omega-3 fatty acids reprogram liver gene expression away from fat storage.
- DGAT2: VLDL synthesis pathway (key hepatic enzyme)
- ↑ PPAR-α: Fatty acid oxidation (activated by EPA/DHA)
- ↓ SREBP-1c: Lipogenesis transcription (suppressed)
- ↓30%: Hepatic TG output (at high dose)
Suppressing lipogenesis
Omega-3 fatty acids downregulate SREBP-1c, cutting fat synthesis.
Boosting fatty acid oxidation
PPAR-alpha activation shifts fatty acids toward burning, not storage.
Reduced synthesis and increased oxidation work together.
Less substrate for VLDL
Fewer triglycerides assembled means less VLDL secreted.
Triglyceride Level Declines
Blood triglycerides fall over weeks, tracking dose and baseline severity.
- ~45%: Max TG reduction (severe hypertriglyceridemia)
- linear: Dose-response slope (0–4 g/day)
- minimal: HDL-C change (variable across trials)
- may rise: LDL-C change (with EPA+DHA mix)
Dose-response curve
Triglyceride reduction scales roughly linearly with omega-3 dose.
Severity affects magnitude
Higher baseline triglycerides show larger absolute drops.
Severe hypertriglyceridemia can fall by up to 45 percent.
Timeline to full effect
Maximal triglyceride lowering typically takes four to eight weeks.
Cardiovascular Evidence Assessment
Triglyceride-lowering is consistent, but cardiovascular event evidence is mixed.
- -25%: REDUCE-IT (EPA-only) (MACE, icosapent ethyl)
- no benefit: STRENGTH (EPA+DHA) (trial halted)
- -19%: JELIS (Japan) (events, EPA add-on)
- no benefit: VITAL (low-dose) (1 g/day general pop)
Triglyceride evidence is strong
Multiple trials confirm consistent, dose-dependent triglyceride lowering.
Cardiovascular evidence is mixed
Pure EPA trials show benefit; EPA+DHA trials often don't.
REDUCE-IT succeeded with EPA-only; STRENGTH with EPA+DHA failed.
Why results diverge
Formulation, dose, and comparator oil may explain differences.
Key cardiovascular outcome trials