The article by Philip C. Calder discusses the role of long-chain omega-3 fatty acids (n-3 PUFAs) in modulating inflammatory processes. The composition of cell membranes, particularly the balance between n-6 and n-3 fatty acids, plays a crucial role in inflammation. Arachidonic acid (n-6) is typically abundant in cells involved in inflammation, but the levels of arachidonic acid and the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can be altered by oral administration of EPA and DHA. This change in fatty acid composition affects membrane fluidity, cell signaling, and the production of lipid mediators such as eicosanoids. Eicosanoids derived from arachidonic acid have pro-inflammatory properties, while those from EPA and DHA often have different, often anti-inflammatory, properties. Additionally, EPA and DHA can generate resolvins, which are anti-inflammatory and resolve inflammation. The article also reviews the impact of n-3 PUFAs on leukocyte chemotaxis, adhesion molecule expression, and inflammatory cytokine production, highlighting their potential therapeutic benefits in conditions with an inflammatory component, such as rheumatoid arthritis and cardiovascular diseases. The anti-inflammatory effects of n-3 PUFAs suggest that they may be useful as therapeutic agents in various inflammatory disorders.The article by Philip C. Calder discusses the role of long-chain omega-3 fatty acids (n-3 PUFAs) in modulating inflammatory processes. The composition of cell membranes, particularly the balance between n-6 and n-3 fatty acids, plays a crucial role in inflammation. Arachidonic acid (n-6) is typically abundant in cells involved in inflammation, but the levels of arachidonic acid and the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can be altered by oral administration of EPA and DHA. This change in fatty acid composition affects membrane fluidity, cell signaling, and the production of lipid mediators such as eicosanoids. Eicosanoids derived from arachidonic acid have pro-inflammatory properties, while those from EPA and DHA often have different, often anti-inflammatory, properties. Additionally, EPA and DHA can generate resolvins, which are anti-inflammatory and resolve inflammation. The article also reviews the impact of n-3 PUFAs on leukocyte chemotaxis, adhesion molecule expression, and inflammatory cytokine production, highlighting their potential therapeutic benefits in conditions with an inflammatory component, such as rheumatoid arthritis and cardiovascular diseases. The anti-inflammatory effects of n-3 PUFAs suggest that they may be useful as therapeutic agents in various inflammatory disorders.