Omega-3: Heart, Mood, and What the Label Isn't Telling You

Heart disease is the leading cause of death in women, and risk rises noticeably after menopause — estrogen had been doing quiet favours for your blood vessels and lipid profile, and those favours stop. So it is reasonable that omega-3 comes up. It is also worth being precise about what it does and does not do.

The two that matter

Marine omega-3s are EPA and DHA. Plant omega-3 (ALA, from flax, chia, walnuts) is a different molecule that your body converts to EPA and DHA at a conversion rate that is low — commonly cited in the single-digit percentages, and lower still for DHA. Plant sources are good food. They are not an efficient substitute if the goal is raising EPA and DHA.

Where the evidence is strongest

Triglycerides. This is the least contested effect. Prescription-strength omega-3 (2–4 g of EPA+DHA daily) reliably lowers triglycerides, often by 20–30%. That is a pharmacological dose, not a supermarket dose.

Cardiovascular outcomes: mixed, and the details matter. Large trials of modest-dose fish oil in generally healthy populations have mostly been null. Trials using high-dose purified EPA in people with elevated triglycerides already on statins have shown meaningful event reduction. The reasonable reading is that omega-3 is a targeted lipid intervention for specific risk profiles, not a general-population heart protector you take because it seems healthy.

Mood. Meta-analyses of omega-3 in depression are genuinely positive but conditional: the benefit is concentrated in formulations that are predominantly EPA (at least 60% EPA), at doses around 1–2 g of EPA daily, and the effect is clearest as an adjunct to treatment rather than a replacement for it. DHA-dominant products have not shown the same signal. If you buy a general fish oil expecting mood benefit, you are probably buying the wrong ratio.

Other claims. Joint discomfort in inflammatory arthritis has modest supportive evidence. Dry eye has mixed evidence. Cognitive protection remains unproven despite heavy marketing.

Reading the label properly

This is the part that costs people money.

A bottle advertising "1,000 mg fish oil" is describing the weight of the oil, not the omega-3 content. A typical such capsule contains around 300 mg of combined EPA+DHA — the rest is other fats. To reach 1 g of EPA+DHA you might need three or four capsules.

So: turn the bottle around and read the EPA and DHA numbers per serving, and note how many capsules a "serving" is. Then compare cost per gram of EPA+DHA rather than cost per bottle. Concentrated products are usually cheaper on that basis despite a higher shelf price.

Two more label points:

• Triglyceride form vs ethyl ester. Re-esterified triglyceride form is somewhat better absorbed. It is a real but modest difference; it is not worth triple the price.
• Third-party testing. Look for IFOS, USP, or NSF marks. These test for oxidation (rancid fish oil is common and unpleasant) and heavy metals.

Practical guidance

Food first, genuinely. Two servings of fatty fish per week — salmon, sardines, mackerel, anchovies, herring — gets most people to a reasonable intake. Small oily fish are cheap, low in mercury, and widely available across Latin America. Canned sardines are one of the best nutritional value propositions in any supermarket.

If supplementing for general intake: 1,000–2,000 mg of combined EPA+DHA per day, taken with a meal containing fat. Fridge storage reduces the aftertaste and slows oxidation.

If supplementing for mood, as an adjunct: look specifically for an EPA-dominant product providing ~1,000–2,000 mg EPA daily, and treat it as a twelve-week trial alongside — not instead of — proper care.

If your triglycerides are high: that is a conversation with your doctor about prescription omega-3, not a supplement decision.

Who should check with a doctor

Omega-3 has mild antiplatelet effects. Talk to your doctor before high-dose supplementation if you take anticoagulants such as warfarin or a DOAC, if you take antiplatelet drugs, or if you have surgery scheduled. Standard dietary doses are not a concern for most people, but a 3-gram-a-day regimen alongside blood thinners deserves a conversation. High doses have also been associated with a small increase in atrial fibrillation risk in some trials, which is another reason not to megadose without a reason.

The bottom line

Omega-3 is a good, safe, modestly effective supplement with two well-supported uses — lowering triglycerides and supporting mood treatment with EPA-dominant formulas — and a lot of claims around the edges that are not carried by the data. Buy on EPA+DHA content, not on capsule weight. And eat the sardines.