A new review by Fenton and colleagues states that increasing long chain omega 3 fatty acid (LCFA) intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may have adverse health outcomes. Let’s discuss this statement. The conclusions were drawn from a summary of mouse studies where dietary EPA/DHA intakes were manipulated and immune responses to pathogens were assessed. As expected, manipulating the type of fat (saturated, monounsaturated, polyunsaturated) and amount (% of total energy intake) in the diet exerted physiological changes in membrane and red blood cell composition and cellular signaling pathways. In effect, mice (and people) are made of what they eat.