Omega-3 Fatty Acids

Omega-3s are essential polyunsaturated fatty acids the body cannot make. Three matter: short-chain ALA (α-linolenic acid, from plants) and long-chain EPA and DHA (from marine sources). Only long-chain forms have robust clinical evidence — ALA conversion to EPA/DHA is inefficient (~5–10%).

Daily requirements

• ALA (adequate intake): 1.6 g/day men, 1.1 g/day women.
• EPA + DHA: no formal RDA; expert consensus 250–500 mg/day combined for cardiovascular health, 1,000+ mg for established heart disease.
• Pregnancy / lactation: at least 200–300 mg DHA/day for fetal neurodevelopment.

Cardiovascular evidence

The largest recent trials have produced mixed results:

• REDUCE-IT (2019) — icosapent ethyl (highly purified EPA) 4 g/day cut major cardiovascular events by 25% in high-risk patients on statins.
• STRENGTH (2020) — mixed EPA+DHA at 4 g/day showed no benefit vs corn oil placebo. The EPA-only formulation, not "fish oil in general," appears to drive the REDUCE-IT signal.
• VITAL (2019) — 1 g/day of standard fish oil in the general population showed no reduction in major cardiovascular events, small reduction in myocardial infarction.
• Standard OTC fish oil (1 g/day) — modest triglyceride reduction (~10–15%), unclear clinical event impact for primary prevention.

For post-MI or high triglyceride patients, prescription EPA (icosapent ethyl) is the evidence-based choice. For general prevention, eating fatty fish twice a week is more supported than a supplement.

Best sources

• Salmon, farmed (3 oz): 1,800 mg EPA+DHA
• Mackerel, Atlantic (3 oz): 1,000 mg
• Sardines (3 oz): 840 mg
• Anchovies (3 oz): 950 mg
• Herring (3 oz): 1,700 mg
• Flaxseed (1 tbsp ground): 2,400 mg ALA (~120–240 mg EPA/DHA equivalent after conversion)
• Chia seeds (1 oz): 5,000 mg ALA
• Walnuts (1 oz): 2,500 mg ALA

Fish oil vs algae oil

Algae oil provides direct EPA and DHA — fish get their omega-3s by eating algae in the first place. Algae oil is vegan, cleaner (no methylmercury or persistent-pollutant concerns), and equally effective. Cost has fallen; it's a legitimate substitute for fish oil.

Fish oil supplement quality

• Read the label: look for combined EPA+DHA per serving, not total "fish oil" mass. A 1,000 mg fish oil capsule typically has only 300 mg EPA+DHA.
• Freshness matters — rancid fish oil (fishy burps, off smell) is common and may be harmful. Cold-store after opening.
• Third-party tested for oxidation and heavy metals (IFOS, USP) is worth the small premium.
• Triglyceride and re-esterified triglyceride forms absorb better than ethyl ester forms.