Taking daily supplements of fish or soy oil may improve cardiac function and protect against heart attacks in the short-term, say researchers from Emory University School of Medicine. The study results are the first to show that soy oil increases heart rate variability (HRV), a measure of cardiac autonomic function.

“Our findings contradict the current belief in the medical community that increasing the intake of omega-3 fatty acids produces only long-term cardiac benefits,” said the study’s lead author, Fernando Holguin, MD. “In fact, our study group showed improvements in heart function in as little as two weeks.”

Researchers took the HRV of 58 elderly patients every other day for two months to establish an HRV baseline for each participant. For 11 weeks, half of the study participants took a daily 2 gram supplement of fish oil, which contains marine-derived omega-3 fatty acids, and the other half took a daily 2 gram supplement of soy oil, which contains plant-derived omega-3 fatty acids. The omega-3 fatty acids improve heart function by providing greater variability between beats, therefore reducing the risk of arrhythmia and/or sudden death. They found that both oils, but especially fish oil, led to an improvement in HRV measurements.

Dr. Holguin said, “Taking a daily supplement of fish or soy oil may help reduce the risk of suffering an adverse cardiovascular event, such as arrhythmia or sudden death, especially in persons with known cardiovascular disease or at increased risk for it, such as those with lipid disorders, advanced age, hypertension, a history of smoking, and family history of heart disease.”

American College of Chest Physicians, April 11, 2005