In this Nutrition Masters Course on Omega-3 Fatty Acids, the biochemistry, functions, sources, recommendations, and status (i.e., nutrient gaps and deficiency) are explored. Omega-3 vs. 6 polyunsaturated fatty acids (PUFAs) are differentiated in this discussion. Next, the evidence-based roles of omega-3 fatty acids in disease prevention and treatment are covered for a variety of life stages and conditions such as: pregnancy, infant and children’s health, asthma, cardiovascular disease, muscle function, cognition, mood, diabetes, NAFLD, age-related macular degeneration, and rheumatoid arthritis. Finally, the quality determinants and safety information for omega-3 oils are discussed, with comparisons drawn between fish, krill, algal sources.