Fish oil protects heart from mental stress – the omega 3 fatty acid secret revealed
A new study by scientists at the Michigan Technological University suggests that fish oil might alleviate the bad effects of mental stress on the heart. The omega 3 fatty acids in fish oil have long been thought to protect against heart diseases. In fact the American Heart Association currently recommends eating at least two servings of fish a week, particularly varieties rich in omega 3 fatty acids. However, how omega 3 fatty acids help the heart was not clearly known.
The findings show that volunteers who took fish oil supplements for several weeks had a blunted response to mental stress in several measurements of cardiovascular health, including heart rate and muscle sympathetic nerve activity (MSNA), part of the "fight or flight" response, compared to volunteers who took olive oil instead. The results may explain why taking fish oil could be beneficial to the heart and might eventually help doctors prevent heart disease in select populations.
Dr. Jason R. Carterand his colleagues at the Michigan Technological University worked with 67 adult volunteers. At the beginning of the study, each volunteer underwent a battery of tests to assess cardiovascular function, including heart rate, blood pressure, MSNA, and blood flow through the forearm and calf. These tests were performed first when the volunteers were at rest, and then again while they were performing a mental arithmetic test while the investigator encouraged them to hurry, a situation designed to induce acute mental stress. The study subjects were then nearly equally assigned to take either 9 grams of fish oil per day or 9 grams of olive oil, a placebo that hasn't been shown to have the same beneficial cardiovascular effects as fish oil. None of the volunteers were aware of which supplement they were taking. After 8 weeks of this intervention, the study subjects underwent the same tests again.
The researchers found that test results didn't change between the two groups of study subjects when they were at rest. However, results for the volunteers who took fish oil and those who received the placebo differed significantly for some of the tests during the mental stress. Those in the fish oil group showed blunted heart rate reactivity while they were stressed compared to those who took olive oil. Similarly, the total MSNA reactivity to mental stress was also blunted in the fish oil group.
These results show that fish oil could have a protective effect on cardiovascular function during mental stress, a finding that adds a piece to the puzzle on why taking fish oil helps the heart stay healthy, the authors suggest. Future studies might focus on the effects of taking fish oil for longer time periods and examining this effect on older populations or people with cardiovascular disease.
"Overall," the study authors say, "the data support and extend the growing evidence that fish oil may have positive health benefits regarding neural cardiovascular control in humans and suggest important physiological interactions between fish oil and psychological stress that may contribute to disease etiology."
Jason R. Carter, Christopher E. Schwartz, Huan Yang, and Michael J. Joyner Fish Oil and Neurovascular Reactivity to Mental Stress in Humans. American Journal of Physiology – Regulatory, Integrative, and Comparative Physiology. February 13, 2013, doi: 10.1152/ajpregu.00031.2013