Introduction
Omega-3 fatty acids are a group of essential polyunsaturated fats that play a vital role in human health. They are called “essential” because the human body cannot synthesize them and must obtain them through diet. The three most important omega-3 fatty acids are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). While ALA is mainly found in plant oils, EPA and DHA are primarily derived from marine sources such as fish and algae.
Chemical Structure and Classification
Omega-3 fatty acids are characterized by the presence of a double bond three carbon atoms from the methyl end of the fatty acid chain. This chemical structure affects their behavior in the body, influencing cell membrane fluidity and gene expression.
Classification:
- ALA (18:3 n-3) – Found in flaxseed, chia seeds, walnuts.
- EPA (20:5 n-3) – Found in fatty fish like salmon and mackerel.
- DHA (22:6 n-3) – Found in fish, fish oil, and algae.
Biological Functions
Omega-3 fatty acids are vital for many physiological processes:
- Cell membrane composition: DHA is a major structural component of the brain and retina.
- Anti-inflammatory activity: EPA and DHA produce eicosanoids and resolvins, which help reduce inflammation.
- Cardiovascular regulation: Omega-3s support normal blood pressure, reduce triglycerides, and improve endothelial function.
- Neurological development: DHA is critical for fetal and infant brain development.
Cardiovascular Health
Multiple studies confirm that omega-3s are beneficial for heart health. They lower blood triglyceride levels, reduce blood pressure slightly, and prevent platelet aggregation.
According to the American Heart Association (AHA), consuming EPA and DHA helps in reducing the risk of coronary heart disease and sudden cardiac death.
Cognitive and Mental Health
Omega-3s, especially DHA, are essential for brain health:
- Cognitive decline: Adequate intake may delay age-related cognitive decline and Alzheimer’s disease.
- Depression and anxiety: EPA has shown antidepressant effects in clinical studies.
- ADHD and neurodevelopment: Supplementation has shown improvements in attention and behavior in children.
Anti-inflammatory and Immune Function
Omega-3 fatty acids help reduce the levels of pro-inflammatory cytokines and may be beneficial in managing autoimmune and inflammatory diseases such as:
- Rheumatoid arthritis
- Ulcerative colitis
- Psoriasis
- Asthma
Pregnancy and Infant Development
Pregnant women are advised to consume DHA for proper fetal brain and visual development. DHA is crucial during the last trimester when the brain undergoes rapid growth.
Breast milk also contains DHA, which supports infant development.
Dietary Sources
Natural food sources:
- Fatty fish (salmon, mackerel, sardines)
- Chia seeds, flaxseed, and walnuts (ALA)
- Seaweed and algae (vegetarian DHA/EPA)
Supplements:
- Fish oil capsules
- Krill oil
- Algal oil (vegan)
Recommended Intake
According to EFSA and NIH guidelines:
- ALA: 1.1g/day (women), 1.6g/day (men)
- EPA + DHA: 250–500 mg/day for adults
- Higher doses (2–4g/day) for those with high triglycerides
Deficiency and Risks
Symptoms of omega-3 deficiency may include:
- Dry skin and eyes
- Fatigue
- Poor memory
- Mood swings or depression
High doses above 3g/day should only be taken under medical supervision as they may affect blood clotting.
Clinical Applications
Omega-3s are used therapeutically in:
- Cardiovascular disorders
- Depression and mood disorders
- Inflammatory bowel disease
- Metabolic syndrome
- Skin conditions (eczema, acne)
References (APA Style)
- Calder, P. C. (2015). Marine omega-3 fatty acids and inflammatory processes: Effects, mechanisms and clinical relevance. Biochimica et Biophysica Acta (BBA) – Molecular and Cell Biology of Lipids, 1851(4), 469–484. https://doi.org/10.1016/j.bbalip.2014.08.010
- Swanson, D., Block, R., & Mousa, S. A. (2012). Omega-3 fatty acids EPA and DHA: Health benefits throughout life. Advances in Nutrition, 3(1), 1–7. https://doi.org/10.3945/an.111.000893
- Mozaffarian, D., & Wu, J. H. Y. (2011). Omega-3 fatty acids and cardiovascular disease: Effects on risk factors, molecular pathways, and clinical events. Journal of the American College of Cardiology, 58(20), 2047–2067. https://doi.org/10.1016/j.jacc.2011.06.063
- Innes, J. K., & Calder, P. C. (2020). Omega-6 fatty acids and inflammation. Prostaglandins, Leukotrienes and Essential Fatty Acids, 132, 102422. https://doi.org/10.1016/j.plefa.2018.03.004
- Riediger, N. D., Othman, R. A., Suh, M., & Moghadasian, M. H. (2009). A systemic review of the roles of n-3 fatty acids in health and disease. Journal of the American Dietetic Association, 109(4), 668–679. https://doi.org/10.1016/j.jada.2008.12.022
