There is considerable evidence suggesting that regular consumption of omega-3 fatty acids prevents cardiovascular diseases, including atherosclerosis and thrombosis. Most studies, however, have been carried out with fish oils that are rich in eicosapentaenoic acid and docosahexaenoic acid fatty acids, but alpha-linolenic fatty acid, which is a precursor of eicosapentaenoic acid and docosahexaenoic acid, has received little attention. The purpose of the present study was to assess the effect chia seed, which is the highest known vegetative source of alpha-linolenic fatty acid, has on plasma total cholesterol, highdensity lipoprotein (HDL), low-density lipoprotein, triacylglycerol content, and fatty acid profile when fed to rats. Twenty-four male Wistar rats were fed ad libitum 3 diets containing equal energy levels derived from com oil (T-1), chia seed (TA) or chia oil (T-3) for 4 weeks. At the end of the feeding period, 6 rats from each treatment were used for blood analyses. Blood samples were analyzed for total cholesterol, HDL, low-density lipoprotein, triacylglycerol content, and fatty acid composition. Rats fed chia showed a significant decrease in serum triacylglycerol content, 3 and 2.5 times lower than the control for T-2 and T-3, respectively. There was a significant increase in serum HDL cholesterol content, 21.8% and 51% for T-2 and T-3, respectively, with the increase between chia diets being significant (P < .05). Total cholesterol was significantly lower for the T-2 diet compared with the T-3 diet. Serum fatty acid composition showed a significantly higher alpha-linolenic acid content and an improved ratio of omega-6/omega-3 fatty acids for T-2 and T-3 compared with T-1. In summary, the chia diets dramatically decreased triacylglycerol levels and increased HDL cholesterol and omega-3 fatty acid contents in rat serum. These findings suggest that alpha-linolenic-rich chia oil may be an alternative to omega-3 sources for vegetarians and people allergic to fish and fish products. (c) 2005 Elsevier Inc. All rights reserved.