Long-term effects of dietary alpha-linolenic acid from perilla oil on serum fatty acids composition and on the risk factors of coronary heart diseasein Japanese elderly subjects

Although important roles of dietary n-3 fatty acids in the prevention of co ronary heart disease (CHD) have been suggested, long-term effects of dietar y alpha-linolenic acid (ALA, 18:3n-3) have not yet been established under c ontrolled conditions. We tested whether a moderate increase of dietary ALA affects fatty acids composition in serum and the risk factors of CHD. Oxidi zed LDL (OxLDL) was directly measured by ELISA using antibody specific to O xLDL, By merely replacing soybean cooking oil (SO) with perilla oil (PO) (i .e., increasing 3 g/d of ALA), the n-6/n-3 ratio in the diet was changed fr om 4, 1 to 1 : 1. Twenty Japanese elderly subjects were initially given a S O diet for at least 6 mo (baseline period), a PO diet for 10 mo (interventi on period), and then returned to the previous SO diet (washout period). ALA in the total serum lipid increased from 0.8 to 1.6% after 3 mo on the PO d iet, but EPA and DHA increased in a later time, at 10 mo after the PO diet, from 2.5 to 3.6% and 5.3 to 6.4%, respectively (p < 0.05), and then return ed to baseline in the washout period. In spite of increases of serum n-3 fa tty acids, the OxLDL concentration did not change significantly when given the PO diet. Body weight, total serum cholesterol, triacylglycerol, glucose , insulin and HbAlc concentrations, platelet count and aggregation function , prothrombin time, partial thromboplastin time, fibrinogen and PAI-1 conce ntration, and other routine blood analysis did not change significantly whe n given the PO diet. These data indicate that, even in elderly subjects, a 3 g/d increase of dietary ALA could increase serum EPA and DHA in 10 mo wit hout any major adverse effects.