Eicosanoids (20-carbon PUFA derivatives) are signaling molecules that play important roles in inflammatory and other immune responses. In general, eicosanoids derived from omega-3 PUFAs have anti-inflammatory and immunosuppressive effects, while eicosanoids derived from omega-6 PUFAs tend to have mostly pro-inflammatory and immunostimulatory effects, although some omega-6 PUFA derivatives (i.e., lipoxins) have anti-inflammatory properties. While high intakes of omega-3 PUFAs may benefit individuals with inflammatory or autoimmune diseases, increased omega-3 PUFA intakes, especially at supplemental doses, could impair host-defense mechanisms and increase vulnerability to infectious disease. Additionally, conjugated linoleic acid (CLA), a class of isomers of linoleic acid (an omega-6 fatty acid), has been shown in one human study to increase plasma levels of immunoglobulin antibodies IgA and IgM, decrease pro-inflammatory cytokines, and increase an anti-inflammatory cytokine. CLA is found naturally in meat and milk of ruminants but is also available in supplemental form. However, more research is needed to confirm the immune effects of CLA in humans.