Omega-3 (EPA + DHA)

Updated June 3, 2026

EPA and DHA, the two long-chain marine omega-3s, lower triglycerides, reduce inflammatory markers, and support cardiovascular health at the doses used in real trials. The catch is that most people never reach those doses, because the big number on the front of a fish oil bottle is total oil, not the active fatty acids. A 1000 mg softgel often delivers around 180 mg EPA and 120 mg DHA, with the rest being other fatty acids and triglyceride carrier. The number that matters is the combined EPA + DHA on the supplement facts panel, and once you start reading it, the underdosing becomes obvious.

Why these two specifically. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the forms the human body actually uses in cell membranes, eicosanoid signaling, and neural tissue, and they carry the bulk of the human evidence base. The other omega-3 on labels, ALA (alpha-linolenic acid, mostly from flax and chia), is short-chain. Your body can convert ALA to EPA, but the math is unforgiving. Conversion rates from real studies sit around five to ten percent for ALA to EPA and well under one percent for ALA to DHA. Eat no fish, rely on flax, and your DHA status is almost certainly low.

What EPA and DHA do inside the cell goes past the label phrase "anti-inflammatory." Sitting in phospholipid membranes, they displace arachidonic acid, shifting the eicosanoid pool from the more inflammatory series (prostaglandin E2, leukotriene B4) toward less inflammatory counterparts. The bigger story is the specialized pro-resolving mediators. EPA converts into resolvins of the E series. DHA converts into resolvins of the D series, protectins, and maresins. These are not generic anti-inflammatories. They are active resolution signals, the instruction to stop the inflammatory cascade once a threat is cleared and return tissue to baseline. Downstream, that shows up as lower CRP, IL-6, and TNF-alpha across trials. EPA and DHA also suppress NF-kB activation in immune cells, the master switch for inflammatory cytokine output. Less NF-kB firing, fewer inflammatory genes read.

Trial doses cluster in a few clean buckets. For general cardiovascular and inflammation support, 1 to 2 grams of combined EPA + DHA per day produces consistent triglyceride reductions and a modest drop in inflammatory markers like CRP. Higher trial doses around 2 to 4 grams have driven the major triglyceride reductions in cardiology contexts, sometimes with prescription icosapent ethyl. For mood research, EPA-heavy formulations at 1 to 2 grams daily have the better signal. For pregnancy, around 200 to 300 mg of DHA daily is the standard recommendation for fetal brain development, and most prenatal vitamins fall short of it.

The cardiovascular benefit is more than triglyceride reduction. EPA and DHA improve endothelial function, the ability of the artery lining to dilate properly under flow, which shows up as better flow-mediated dilation in vascular studies. They modestly lower blood pressure in people with elevated readings, and reduce vascular inflammation at the plaque level. That is part of why the icosapent ethyl trial (REDUCE-IT) saw a real event reduction in high-risk patients. Membrane fluidity in cardiomyocytes also matters, one mechanism behind the small reduction in resting heart rate at higher doses.

DHA is structural in a way EPA is not. The brain is roughly sixty percent fat by dry weight, and DHA is the dominant long-chain omega-3 in neuronal membranes, especially at the synapse and in retinal photoreceptors. Adequate DHA supports membrane fluidity, neurotransmitter receptor function, and synaptic signaling. Animal and growing human work link DHA status to BDNF expression, the growth factor behind synaptic plasticity. Protectin D1, derived from DHA, calms microglia and reduces neuroinflammation in models of brain injury and aging. This is the layer underneath the cognitive and mood findings. In pregnancy the same biology applies in fast-forward: fetal brain and retina lay down DHA at high rates in the third trimester, which is why prenatal underdosing is a real problem rather than theoretical.

Form is where people overpay. You will see triglyceride, re-esterified triglyceride, and ethyl ester. Triglyceride form is slightly better absorbed than ethyl ester in head-to-head studies, but the absorption gap is roughly twenty to forty percent in most data, not the ten-times difference some marketing implies. Ethyl ester is fine. Take it with a meal that contains some fat and the gap shrinks further. The bigger quality lever is oxidation. Cheap fish oil that has sat on a shelf goes partially rancid, which shows up as a fishy aftertaste and as oxidized lipids that work against the very thing you are buying it for. Freshness matters more than form.

Krill oil and algae oil are the alternative routes. Krill delivers EPA + DHA in phospholipid form, with slightly better bioavailability per mg, but krill capsules contain less EPA + DHA each, so the per-dose cost runs higher. Algae oil is the vegan route, with DHA-dominant or balanced EPA/DHA versions on the market. Algae is the only way to get meaningful DHA without marine animals, and the absorption holds up well.

Timing is forgiving. Take it with food that contains some fat. Splitting two grams across two meals cuts fish burp more than taking it all at once. Keep the bottle in the fridge to slow oxidation.

Safety is straightforward. High-dose omega-3 (above 3 grams per day combined EPA + DHA) can modestly increase bleeding time, which matters on anticoagulants or before surgery. Stop a week or so before elective procedures and clear it with the surgical team. The atrial fibrillation signal in some recent high-dose cardiovascular trials (notably with prescription icosapent ethyl) is real but small in absolute terms; for supplement-dose users in the 1 to 2 gram range, it is negligible based on current data. None of this is medical advice. If you take anticoagulants, are pregnant, are scheduled for surgery, or have any chronic condition, ask a clinician before starting or scaling up.

The version most households need to hear is short. Omega-3 is the most underdosed supplement in most cabinets. Read the EPA + DHA number, target one to two grams combined daily for general use, pick a brand with current freshness testing (look for IFOS or similar third-party certification), store it cold, and take it with a fatty meal. What you actually get. Lower triglycerides, reduced inflammatory markers via real resolution biology, better endothelial function, structural DHA for brain and retina, and proper status for pregnancy. Fancy form premiums are a small upgrade. Freshness and dose are the big ones.