Urinary excretion of and recent N-6-3 fatty acid intake

Epidemiological studies were performed in a Japanese fishing village when catches of fish were highest and in a Japanese farming village with usual fish consumption. Intake of eicosapentaenoic, docosahexaenoic and also arachidonic acid were significantly higher in the fishing village during the 3 days of the study than in the farming village. The correlation between eicosapentaenoic acid intake on the day when urine was collected and excreion of Δ 17-2,3-dinor-6-keto-prostaglandin F_1α, the main urinary metabolite of prostaglandin I₃, was highly significant, whereas there was no correlation between arachidonic or linoleic acid intake and excretion of 2,3-dinor-6-keto-prostaglandin F_1α, the main urinary metabolite of prostaglandin I₂. We suggest that the arachidonic acid pool for prostaglandin I₂ production is not quickly influenced by dietary linoleic or arachidonic acid because of a large pool size of arachidonic acid and a slow conversion of linoleic acid to arachidonic acid, while prostaglandin I₃ formation is directly related to the intake of eicosapentaenoic acid.