Mature adults who had the highest blood levels of omega-3 fatty acids, most commonly found in fish, were 30 percent less likely to later develop an irregular heartbeat than peers with the lowest blood levels of omega-3s, according to a U.S. study. Atrial fibrillation (AF) is a type of arrhythmia, which means that the heart beats in an irregular fashion. This is caused by a distortion of electrical messages that control the steady rhythm of the heart, which we know as the ‘heartbeat’.
Overall, AF affects around two in every 100 people. However, the risk increases with age, with more than one in ten people aged 75 years or more affected. Atrial fibrillation is, therefore, one of the most common types of arrhythmia.
Symptoms are not always obvious but may include palpitations or a fluttering heartbeat, irregular heartbeat, chest pains, dizziness and fainting spells. Treatment is important, even if the AF does not present with any symptoms. Untreated, complications can include stroke and heart attack. There are few treatments for the condition and they largely centre on preventing strokes with blood-thinning drugs. “A 30 percent lower risk of the most common chronic arrhythmia in the United States population is a pretty big effect,” said Dariush Mozaffarian, senior author of the study and a professor at the Harvard School of Public Health. Some previous studies have suggested that people who eat a lot of fish have a lower risk of developing atrial fibrillation to begin with, but others haven’t found the same link. The omega-3 fatty acids measured in the new study, which was published in the journal Circulation, were eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA). They are found in oily fish and some enriched foods, such as eggs, as well as in fish oil supplements.
The earlier studies relied on questionnaires about how much fish people ate, which can only estimate the amount of omega-3s they ingested, Mozaffarian noted. As any given fish species can vary in its omega-3s, this study achieved a more accurate measurement of how much fish oil people in the study actually ingested, the researchers sampled blood from more than 3,300 adults over age 65. Over the next 14 years, they tracked the participants’ health and found that 789 developed atrial fibrillation. Those with the top 25 percent omega-3 levels in their bloodstreams at the beginning of the study were about 30 percent less likely to end up with the arrhythmia compared to those with the bottom 25 percent blood levels. A 30 percent reduction in risk would mean that instead of 25 out of every 100 people developing a condition, only about 17 of every 100 would. Of the three omega-3 fatty acids, high DHA levels were linked to a 23 percent lower risk for atrial fibrillation, while EPA and DPA were not tied to any reduced risk. While these results must be received with some caution as the study doesn’t prove eating fish is responsible for the lower rate of atrial fibrillation, but there is some idea that the fatty acids found in fish could work by stabilising the excitability of heart muscle cells.
The results seem promising enough to warrant further studies that experiment with how fish oil might be used as a potential preventive measure against the arrhythmia.