The Complete Guide to Fish Oil & Omega-3 Supplements

Omega-3 fatty acids are polyunsaturated fats that your body cannot produce on its own — they must come from diet or supplementation. The three main omega-3s are ALA (alpha-linolenic acid, found in plants), EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid). EPA and DHA are the biologically active forms that provide the vast majority of health benefits. The modern Western diet is severely deficient in omega-3s. The omega-6 to omega-3 ratio in ancestral diets was approximately 1:1 to 4:1. Today, it's estimated at 15:1 to 20:1 in the average American diet. This imbalance promotes chronic inflammation, which is at the root of cardiovascular disease, autoimmune conditions, mental health disorders, and many other chronic diseases. Omega-3 supplementation is one of the most well-researched interventions in all of nutrition science, with thousands of clinical trials demonstrating benefits for heart health, brain function, inflammation, joint health, eye health, and mental well-being.

While EPA and DHA are both omega-3 fatty acids, they serve different primary functions: EPA (Eicosapentaenoic Acid) is the primary anti-inflammatory omega-3. It competes with arachidonic acid (an inflammatory omega-6) for the same enzymatic pathways, effectively reducing the production of pro-inflammatory eicosanoids. EPA is particularly important for cardiovascular health (reduces triglycerides by 15-30%), mood and depression (meta-analyses show significant benefits at 1-2g EPA/day), joint inflammation, and skin health. DHA (Docosahexaenoic Acid) is the primary structural omega-3. It makes up approximately 25% of the fat in the brain and 60% of the fat in the retina. DHA is critical for brain development (essential during pregnancy and early childhood), cognitive function throughout life, eye health and visual acuity, and cell membrane fluidity and signaling. For general health, a supplement with both EPA and DHA is ideal. For specific goals: prioritize EPA for inflammation, mood, and heart health; prioritize DHA for brain health and cognitive function.

Dosage recommendations vary by health goal. For general health maintenance, 1,000-2,000mg combined EPA+DHA daily is sufficient for most adults. For heart health and triglyceride reduction, 2,000-4,000mg EPA+DHA daily is recommended — the American Heart Association recommends 2-4g for elevated triglycerides. For depression and mood, 1,000-2,000mg EPA daily with EPA-dominant formulations shows the strongest benefits. For joint health and inflammation, 2,000-4,000mg EPA+DHA daily is needed for anti-inflammatory effects. During pregnancy, 200-300mg DHA minimum (many experts recommend 500-1,000mg DHA) is critical for fetal brain and eye development. Important: These are doses of actual EPA+DHA, not total fish oil. A 1,000mg fish oil capsule typically contains only 300-500mg EPA+DHA. Always check the Supplement Facts panel for EPA and DHA content.

Fish oil supplements come in several molecular forms, and the form significantly affects absorption. The triglyceride (TG) form is the natural form found in fish, where omega-3s are bound to a glycerol backbone. This is the best-absorbed form — approximately 50-70% better absorption than ethyl esters. Look for "triglyceride form" or "rTG" (re-esterified triglyceride) on the label. The ethyl ester (EE) form is a synthetic form created during the concentration process. Less expensive to produce but less well-absorbed. Most budget fish oils use this form. Absorption improves significantly when taken with a high-fat meal. The phospholipid form is found naturally in krill oil and may have superior absorption per milligram, but krill oil capsules contain much less total EPA+DHA than fish oil. The free fatty acid (FFA) form is pre-digested and doesn't require lipase for absorption, making it good for people with fat malabsorption issues. Our recommendation: Choose triglyceride form fish oil for the best balance of absorption, potency, and value.

Not all fish oil is created equal. Look for third-party testing from IFOS (International Fish Oil Standards), NSF, or ConsumerLab, which verify purity, potency, and freshness. Check oxidation levels — fish oil can go rancid, producing harmful lipid peroxides. The TOTOX value should be under 26 (ideally under 10), peroxide value under 5 meq/kg, and anisidine value under 20. Verify heavy metal testing — molecular distillation removes most contaminants, but third-party testing confirms safety. Check EPA+DHA concentration — higher concentration means fewer capsules needed. Standard fish oil is 30% EPA+DHA (300mg per 1,000mg capsule), while concentrated forms offer 50-90%. For sourcing, small cold-water fish (anchovies, sardines, mackerel) are preferred because they have shorter lifespans and accumulate fewer toxins than large fish. For freshness, buy from brands with high turnover, check the manufacturing date, and store opened bottles in the refrigerator.