Several dietary recommendations have been made for marine n-3 polyunsaturated fatty acid (PUFA) intake; however, the effectiveness of these fatty acids has not been thoroughly examined. The aim of this study was to investigate whether public-aimed dietary recommendations for long-chain n-3 PUFA from oily fish or fish oil supplements are efficient in optimizing their status in red blood cells (RBCs) and platelets of healthy middle-aged subjects with low customary fish consumption. In a randomized, cross-over trial conducted over an 8-week period and separated by a 6-month washout period, 33 participants received an oily fish (salmon), providing 274 mg eicosapentaenoic acid (EPA) + 671 mg docosahexaenoic acid (DHA) per day, or a commercial fish oil supplement, providing 396 mg EPA + 250 mg DHA per day. Blood samples were collected before and after each intervention period, and RBCs and platelets were used for analysis of fatty acids. After 8 weeks, there were significant increases in EPA and DHA content in RBCs and platelets with both salmon and fish oil capsules. The increase in EPA in both RBCs and platelets was higher with capsules, whereas the increase in DHA in both RBCs and platelets was higher with salmon. In spite of the quantitative and qualitative differences between n-3 fatty acid profiles in salmon and the fish oil supplement, the overall incorporation of these fatty acids into RBCs and platelets did not differ in our short-term study (P > .05). The sum of EPA + DHA significantly increased in both compartments following dietary recommendations for oily fish and fish oil supplements intake in middle-aged healthy subjects with low baseline long-chain n-3 PUFA status, although targeted values with optimal cardioprotective effect of more than 8% were not achieved.