Possibility of Diarrheal Effect by Eicosapentaenoic Acid (EPA) and Autoxidized EPA

A study on the possibility of diarrhea induced by EPA and autoxidized EPA (EPA-Ox ; 61.6% decomposition) was conducted using several assays on rabbits and suckling mice. The result of loop test of both EPA and EPA-Ox in rabbit intestine showed positive diarrheal effect at the dose of more than 12.5 mg per loop though the degree of effect depended on the rabbit used (no sign was observed in 2 out of 6 rabbits). Effect of EPA-Ox was more intense than EPA. In an oral test with suckling mice, however, neither of the acids showed a diarrheal effect at a dose of up to 5 mg/mouse. When a very small amount (1.0μg) of okadaic acid (OA) was given, positive toxicity identified as a typical diarrheal substance derived from phytoplanktons. Significant positive correlation (γ=0.984, p<0.01) was obtained between fluid accumulation ratio (FAR) calculated from the result of the loop test in rabbits and percent of dead mice both animals which are usually viewed as a parameter of diarrhea. A large amount of PUFA such as EPA and its oxides is also considered a potential diarrhea inducer, in addition to substances derived from planktons well known for their diarrheal toxin like OA.