Molecular Features, Effective Sources, and Physiological Effects of Omega-3 Unsaturated Fatty Acids on Cardiovascular, Neurological, and Muscular Health, and Clinical Relevance for Several Conditions: A Narrative Review.

Omega-3 fatty acids, essential for various physiological functions, are well recognized for their benefits in cardiovascular, neurological, and inflammatory health. In this narrative review we analyzed and compared the primary sources of omega-3 fatty acids, including plant-derived alpha-linolenic acid (ALA), derived from flaxseed, chia, walnuts, and canola oil; and marine-derived eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), derived from microalgae, fish oil, and krill oil; with a focus on their bioavailability, clinical effects, and practical applications. The findings revealed that compared with marine-derived ALA, EPA and DHA, derived from plants, exhibited far superior bioavailability, which is associated with greater clinical efficacy, particularly in reducing triglycerides (average reductions of 15%-30% with doses of 2-4 g/d), lowering inflammatory markers such as interleukin-6 and tumor necrosis factor-α, achieving significant cognitive improvements, and promoting muscular development and strength. Conversely, ALA demonstrated limited conversion to EPA and DHA, requiring higher doses (>20 g/d) to achieve comparable benefits. Therefore, ALA is less recommended for consumption than EPA and DHA. In specific conditions, such as psychiatric disorders and cardiovascular diseases, formulations with higher EPA:DHA ratios (2:1 or greater) have proven more effective, particularly in alleviating depressive symptoms, with dosages of 1-2 g/d of EPA. The findings of this review also highlighted the relevance of plant-based sources for vegetarian and vegan populations, leading to our proposal that microalgae supplements may be a sustainable and effective alternative. Practical implications underscore the importance of personalized supplementation strategies tailored to the clinical and dietary needs of individuals. However, significant gaps in the literature were identified, including the lack of direct comparisons between sources and the need for standardized dosing and evaluation methods to optimize observed benefits. In this review we have sought to effectively summarize current best practices and recommendations for omega-3 fatty acid supplementation to support general health and also to emphasize the necessity for future research to establish effective doses and scales of impact based on omega-3 fatty acid sources and clinical objectives, facilitating evidence-based nutritional and therapeutic interventions.