 Another surprising fish story out of Massachusetts recently, atrial fibrillation is the most common clinical cardiac arrhythmia, an irregularity of our heartbeat rhythm, which can set you up for a stroke, increase our risk of dementia and heart failure, and significantly shorten our lifespan. Previous findings on the effective diet have been conflicting. Some studies have found alcohol, caffeine, and fish consumption to be good in terms of preventing and resolving atrial fibrillation. And other studies have shown them all to be bad. It's when this kind of situation arises in nutritional science, you'll pull out the big guns and put it to the test in one of the bigger, better studies, like the famous Framingham Heart Study population, like they did here. They found no effect either way, in general, from the consumption of alcohol, caffeine, or fish, but when they looked closer, they observed an association between the consumption of dark fish and atrial fibrillation, a six-fold higher hazard ratio. What they're talking about is basically salmon, the swordfish, bluefish, mackerel, sardines, that kind of thing. They conclude that their findings may suggest a true adverse effect of dark fish and fish oil on certain subtypes of atrial fibrillation, proposing that potential toxins, such as dioxins and methylmercury, accumulate in certain fish, may have a negative effect on cardiac arrhythmia.