The long-chain omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the nutrients with the most robust cardiovascular evidence profile in nutritional pharmacology. They lower triglycerides, have anti-inflammatory effects on the vascular endothelium, have documented antiarrhythmic effects, and reduce platelet aggregation. Yet there's still considerable confusion about how much to take, which sources to choose, and when supplements make sense compared to food alone.

The cardiovascular evidence for omega-3s

The Italian GISSI Prevention Trial (1999, 11,324 post-heart attack patients, 3.5 years follow-up) showed that 1g daily of EPA+DHA reduced all-cause mortality by 20% and cardiovascular mortality by 30%. It was one of the most impressive trials in clinical nutrition. Subsequent studies in different populations yielded less clear results, but the most recent meta-analysis (2020, JAMA Cardiology, 40 trials, over 135,000 participants) confirms: omega-3s reduce major cardiovascular events in people with existing cardiovascular disease or very high triglycerides. Results for primary prevention (healthy people) are less clear, especially at typical dietary doses.

The dose: how much EPA+DHA your heart needs

For cardiovascular prevention in people with cardiovascular disease or high risk: 1-2g daily of EPA+DHA. For triglyceride reduction: 2-4g daily of EPA+DHA (doses above 4g are classified as drugs). For the general healthy population: 250-500 mg daily of EPA+DHA is the EFSA target for general cardiovascular benefits. Two servings of fatty fish per week (sardines, mackerel, salmon) provide approximately 3-4g total EPA+DHA: equivalent to about 500 mg daily on average. This is the realistic dietary target for primary prevention.

The best food sources of EPA and DHA

Wild salmon or ASC-certified (100g cooked): 1,800-2,500 mg EPA+DHA. Mackerel (100g cooked): 2,600 mg. Fresh sardines (100g cooked): 1,400 mg. Herring (100g cooked): 2,400 mg. Anchovies in oil (100g): 2,000 mg. Fresh tuna (100g cooked): 230-300 mg (fresh tuna has less omega-3 than many think). Canned tuna: 100-300 mg (processing reduces omega-3s). Eggs from pasture-raised hens or those fed enriched diets: 100-300 mg per egg. Plant sources (walnuts, flaxseeds, chia) contain ALA, which converts to EPA and DHA with only 5-15% efficiency. They don't replace marine sources for EPA and DHA.

Fish oil supplements: when and which ones

When supplementation makes sense: you can't eat fatty fish 2-3 times weekly, you have high triglycerides, you have a cardiovascular diagnosis (discussed with your cardiologist), or you're vegan (use algae-based DHA+EPA). How to choose quality fish oil: check the mg of EPA+DHA per capsule (not just "fish oil"): a standard 1g capsule contains about 300 mg EPA+DHA; many premium capsules have 500-700 mg. Form: natural triglycerides (rTG) have superior bioavailability to ethyl esters (EE). IFOS certification (International Fish Oil Standards): tests for purity, stability, and absence of contaminants. Freshness: fish oil oxidizes easily. Strong fishy smell = oxidized oil. Quality oil has barely noticeable odor.

EPA vs DHA: differences in benefits

EPA has more pronounced anti-inflammatory effects (inhibits synthesis of pro-inflammatory series 2 prostaglandins) and is more effective for triglyceride reduction. DHA is the primary structural component of the brain (60% of brain lipids) and retina: essential for neurological development and cognitive function. For cardiovascular health, both are relevant. For brain health and during pregnancy, DHA is the priority. Most supplements contain both in varying proportions; oils with higher DHA are preferable for use during pregnancy and for brain health.

How to reach the 500mg EPA+DHA daily target

Two servings of fatty fish per week (sardines: Tuesday, mackerel: Friday) easily cover the target. If you can't eat fish twice weekly: take a 500 mg EPA+DHA supplement daily. If you want to optimize: add ground flaxseeds and walnuts (ALA, partial conversion) as a supplement to marine omega-3s, not as a replacement. The combination of fish + flaxseeds + walnuts in your weekly diet covers EPA, DHA, and ALA synergistically.

How to check your omega-3 status

The Omega-3 Index (percentage of EPA+DHA among total fatty acids in red blood cells) is the reference test for assessing omega-3 status. An index above 8% is associated with low cardiovascular risk. Below 4% is associated with elevated risk. Most Europeans fall between 4 and 6%. The test is available at some private labs. If your index is low despite regular fish consumption, consider that some people have reduced delta-6-desaturase enzyme activity and convert little ALA: for them, direct EPA+DHA supplementation is more effective than plant foods.

Store fish oil correctly

Fish oil oxidizes rapidly: always store in the refrigerator after opening, away from light, and use within 2-3 months of opening. If the container opens with a strong, rancid smell: discard and replace. Oxidized fish oil can have pro-oxidative effects contrary to the intended benefits. Buy small, fresh containers rather than large quantities.