High Omega-3 Fat Intake Improves Insulin Sensitivity and Reduces CRP and IL6, but does not Affect Other Endocrine Axes in Healthy Older Adults

Aging diminishes hormone secretion and target cell responsiveness, possibly due to loss of cell membrane fl uidity or alteration of membrane phospholipids affecting signal transduction. We investigated whether a high -3 polyunsatu- rated fatty acid diet would improve endocrine function in 6 men and 6 women aged over 60 years. Subjects fi rst ate an isocaloric control diet for 6 weeks, followed by an 8-week experimen- tal diet, which included 720 g of fatty fi sh weekly plus 15 ml of sardine oil daily. In the last week, we measured RBC membrane fatty acids on each diet, performed pituitary, adrenal, hepatic, and Leydig cell endocrine provocative testing, and assayed selected cytokines. We also assessed insulin sensitivity utilizing octreotide insulin suppression testing and assessed free fatty acid (FFA) responses to isoproteronol. Insulin sensi- tivity increased signifi cantly after 8 weeks on the -3 diet and FFA responses trended lower. Serum C-reactive protein was signifi cantly reduced and a trend towards lower IL-6 was noted. No dif- ferences were found in other metabolic param- eters, adiponectin levels, or hormone responses. We conclude that, in older people, high -3 consumption increases insulin sensitivity, may reduce FFA mobilization by catecholamines, and reduces infl ammatory markers, but did not alter endocrine responsiveness after 8 weeks.