Omega-3 fish oil and atrial fibrillation:
Supplementation with 1 gram of omega-3 fish oil for 1 year did not reduce the incidence of recurrent atrial fibrillation (77). Few studies have shown benefit of using omega-3 fish oil for prevention or recurrence of atrial fibrillation (72).
Omega-3 fish oil adverse reactions and interactions:
- A total of 10 studies were reviewed by Villani AM et al to determine potential serious adverse effects of fish oil at a dose of under 1.86 grams per day (78). It was found that there were no serious adverse effects reported in 994 adults over 59 years of age and other non-serious adverse effects were not significantly different from placebo (78).
- Fish oil has been reported to affect platelet aggregation, reduce vitamin K dependent factors which may be associated with an increased anticoagulation (reduce blood clotting) effect. Consumption should be avoided when taking anticoagulants like aspirin, warfarin, or ticlopidine because of the potential increased risk of bleeding (79).
- A case of a 67-year old woman taking warfarin (1.5 mg/day), an increase in her fish oil intake from 1 g/day to 2 g/day was associated with an increase in time for blood to clot as measured by the international normalized ratio (INR) which went from 2.8 to 4.3 within 1month, and decreased to 1.6 after the fish oil dose was reduced (80).
- An intake of 6 grams per day of docosahexaenoic acid (DHA) found no significant difference found in blood coagulation, platelet function, or thrombotic parameters including prothrombin time, activated partial thromboplastin time, antithrombin-III levels, and platelet aggregation (81).
- Fish oil may contain harmful contaminants such as heavy metals including mercury, dioxins, and polychlorinated biphenyls (PCBs). This risk can be reduced by purchasing fish oil that has undergone a purification process specified on the label (approved by the FDA, EPA, or US Pharmacopeia) (82)
Calcium intake, cardiovascular disease, and stroke:
Research shows that potential health risks occur with taking calcium supplements. As a result, it is advisable for men and women to avoid a total daily calcium intake of over 1400 mg per day from diet and supplements due to an increased risk of cardiovascular mortality. Preventive Health Advisor supports obtaining the recommended daily intake of calcium from food sources rather than supplements, but not to exceed calcium intake of over 1400 mg per day. Calcium supplements are not advised until further research clarifies these findings. Risk may outweigh the benefits especially if the amount of calcium taken in the diet is unknown.