The cytokine interleukin -6 (IL-6) produces an acute inflammatory response to exercise which is important for muscle hypertrophy.  In this month's issue of MD, Dan Gwartney wrote a great article called "IL-6: Friend or Foe?"  The article explains how IL-6 has acute beneficial effects on muscle hypertrophy but also has some detrimental effects at chronic high levels.  Researchers from the Kronos Longevity Research Institute reported that a diet high in omega-3 fatty acids reduced CRP and IL-6 but did not affect hormones in older adults.  In the study, subjects first ate an isocaloric western control diet for 6 weeks, followed by an 8-week experimental diet, which contained 30 % of calories as triglycerides, of which 30 % were polyunsaturated (walnut, flax, or canola oil high in omega -3 PUFA), 40 % monounsaturated (olive oil), and 30 % saturated (butter, animal fats).  The diet also which included 720 g of fatty fish weekly plus 15 ml of sardine oil daily. Subjects were asked to use only olive oil for preparing foods and salad dressings and to consume 1 tablespoon of fish oil per day. The results of the study are consistent with other clinical and epidemiological studies reporting the anti-inflammatory effects of high omega -3 diets and/ or omega-3 supplements. The omega-3 fats are key components of the Japanese and Mediterranean diets, and are believed to contribute to the low heart disease rates in those regions in part by decreasing inflammation, as evidenced by decreasing C-reactive protein and IL-6.  A high consumption of omega-3 fatty acids may suppress muscle growth due to suppressed levels of IL-6 but more research is needed.  Omega-3 fatty acids are great for cardiovascular health and increasing insulin sensitivity, but may suppress muscle growth by inhibiting inflammation.

-Tsitouras PD, Gucciardo F, Salbe AD, Heward C, Harman SM. High Omega-3 Fat Intake Improves Insulin Sensitivity and Reduces CRP and IL6, but does not Affect Other Endocrine Axes in Healthy Older Adults. Horm Metab Res. 2008 Mar;40(3):199-205.