Results of a review focusing on animal feeding trials suggested that omega-3 can both improve and impair host resistance to a number of pathogens. (1) Dietary fatty acids can modulate disease activity via immunoregulation and inflammation. They may affect the immune system and autoimmune disease by regulating gene expression and signal transduction pathways, altering the production of eicosanoids and cytokines, and affecting the action of antioxidant enzymes. (2, 3) Dietary PUFAs such as omega-3 affect gene expression by regulating transcription factors that play a major role in hepatic carbohydrate, fatty acid, triglyceride, cholesterol and bile acid metabolism. (1) Placebo-controlled trials show that consumption of fish oil may decrease disease activity and result in a lowered use of anti-inflammatory drugs in chronic inflammatory disease. (4)

As noted in earlier HIV Nutrition Update issues, recommendations by the American Heart Association note that healthy people should eat omega-3 fatty acids from fish and plant sources to affect heart health in positive ways. Fish convert alpha-linolenic acid (the omega-3 building block) into EPA and DHA. Consumption of EPA and DHA can help to lower triglyceride levels but usually do not lower low-density lipoprotein cholesterol (LDL) or raise high-density lipoprotein cholesterol  (HDL) levels.