Omega-3
Also known as: Omega-3 fatty acids
Omega-3 fatty acids are a family of polyunsaturated fats whose first double bond lies three carbon atoms from the methyl end of the molecule. Important members include alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). "Omega-3" is not another name for fish-oil capsules: it describes fatty acids found in foods, the body, and several types of supplement.
ALA is an essential fatty acid because humans cannot make it from scratch. It occurs in foods such as flaxseed, chia, walnuts, and canola oil. EPA and DHA occur mainly in fish and seafood, while microalgae are their original marine source and can supply them directly in algal oil. The body can convert some ALA to EPA and then DHA, but conversion is limited and varies among individuals. That does not make plant sources worthless; it means ALA and preformed EPA or DHA should not be treated as nutritionally identical.
Omega-3 fatty acids are incorporated into cell membranes and participate in signaling pathways. DHA is particularly abundant in the retina and brain, while EPA is a precursor to several lipid mediators. These physiological roles do not mean that progressively larger doses keep improving health or training. Effects depend on the fatty acid, baseline intake, population, dose, comparator, and outcome. Evidence for lowering blood triglycerides, for example, does not automatically establish better strength, muscle growth, less soreness, or fewer cardiovascular events.
The NIH evidence review on omega-3 fatty acids distinguishes ALA, EPA, and DHA; food patterns, ordinary supplements, and high-dose prescription products also should not be conflated. There is no single scientifically established "ideal" omega-6-to-omega-3 ratio for every diet. Looking at adequate absolute intake and the foods being replaced is usually more informative than trying to force one ratio.
When considering an omega-3 supplement, read the listed amounts of EPA and DHA rather than the larger total amount of fish oil. Algal products may provide DHA alone or DHA with EPA. Source, freshness, storage, oxidation control, allergen information, and credible independent testing matter. High intakes can cause gastrointestinal effects and may interact with anticoagulant treatment; some high-dose trials in people at elevated cardiovascular risk have also found more atrial fibrillation. A medical product used for a diagnosed condition therefore should not be copied with an over-the-counter product or a self-selected dose.