The combined effects of N-3 fatty acids and aspirin on hemostatic parameters in man

Both fish oils and aspirin are readily available to the consumer as over-the-counter preparations. Since both of these products have been shown to prolong bleeding times, it is possible that hemostasis might be adversely affected in subjects taking them in combination. This study was undertaken to examine the effects of n-3 fatty acids and aspirin on platelet function. Eight healthy men took a total of 485 mg of aspirin over 3 days before beginning two weeks of fish oil supplementation (4.5 g of n-3 fatty acids/day). Subjects continued with fish oil while resuming aspirin treatment for 3 days. Aspirin alone prolonged bleeding times by 34% (p less than 0.05). Fish oil alone raised bleeding times only slightly (9%; N.S.), but aspirin plus fish oil raised them by 78% (p less than 0.01). The increase in bleeding times with the combination (78%) was not significantly different than the sum of the individual increases (43%). The effects of fish oil and aspirin on platelet aggregation were investigated using single and dual agonists. Although fish oil alone did not significantly raise aggregation thresholds for collagen, arachidonic acid, or PAF, it did reduce the extent of aggregation with collagen. When challenged by single or dual agonists, the combination of fish oil and aspirin did not make platelets less sensitive than did aspirin alone. Since fish oil and aspirin had synergistic effects on bleeding times, but not on platelet aggregation, these two substances appear to affect hemostasis by different mechanisms.