Omega-3 Fatty Acids
Essential Fatty Acid
Overview
- Definition: Omega-3 fatty acids are a family of polyunsaturated fatty acids (PUFAs) containing a double bond three carbons away from the terminal methyl group.
- Bioactive Forms: The most biologically active forms for humans are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
- Function: Incorporated into cell membranes, they serve as precursors for anti-inflammatory lipid mediators. Their primary purpose is to modulate membrane fluidity, gene expression, and signaling pathways influencing cardiovascular, neural, and metabolic health.
Chemistry
- EPA: Eicosapentaenoic acid (EPA) – C₂₀H₃₀O₂, IUPAC: (5Z,8Z,11Z,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid.
- DHA: Docosahexaenoic acid (DHA) – C₂₂H₃₂O₂, IUPAC: (4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoic acid.
- Structural Features: Both are long-chain polyunsaturated fatty acids with multiple cis-double bonds spaced every three carbons (the “omega-3” position). The high degree of unsaturation confers low oxidative stability, measured by peroxide value. EPA has five double bonds; DHA has six, giving DHA a higher melting point and greater membrane fluidity. The carboxylic acid terminus (pKa≈4.8) allows incorporation into phosphatidylcholines and triglycerides.
- Solubility and Stability: EPA/DHA are lipophilic, soluble in organic solvents (e.g., chloroform, hexane) and are vulnerable to oxidation; thus, antioxidants (e.g., vitamin E) are added to commercial formulations to preserve integrity.
Sources & Quality
- Marine Sources: Marine sources dominate: fatty fish (salmon, mackerel, sardines) contain natural EPA/DHA; algae (Schizochytrium, Nannochloropsis) provide vegan DHA/EPA via fermentation.
- Fish Oil Extraction: Fish-oil supplements are extracted by cold-press or supercritical CO₂, then molecularly distilled to remove contaminants (PCBs, dioxins).
- Algal Oil Production: Algal oils are produced by cultivating micro-algae, then harvesting and purifying the lipids; this route avoids marine-derived pollutants and is sustainable.
- Quality Metrics: Quality metrics include EPA/DHA content per capsule, oxidation status (PV <5 meq O₂/kg), and absence of heavy metals (≤0.5 ppm mercury). Pharmaceutical-grade products meet USP/EP standards and are often “phytochemical-free” (i.e., free of added flavors). Sourcing from certified, third-party tested brands ensures potency, purity, and consistent EPA/DHA ratios.
Where to Buy Omega-3 Fatty Acids
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