The heart health benefits of fish oil may be partly linked to its ability to blunt the detrimental cardiovascular effects of mental stress, says a new study from Michigan Technological University.
Eight weeks of taking a daily fish oil supplement at a dose of nine grams per day, giving daily EPA and DHA doses of 1.6 gram of EPA and 1.1 grams of DHA, were associated with reduced increases in heart rate and muscle sympathetic nerve activity related to mental stress.
The new study, published in the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology , provides “new mechanistic insight regarding the influence of fish oil supplementation on neural cardiovascular reactivity,” explained the researchers.
“Overall, 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.”
The heart health benefits of fish oil, and the omega-3 fatty acids it contains, are well-documented, being first reported in the early 1970s by Dr Jorn Dyerberg and his co-workers in The Lancet and The American Journal of Clinical Nutrition.
To date, the polyunsaturated fatty acids (PUFAs) have been linked to improvements in blood lipid levels, a reduced tendency of thrombosis, blood pressure and heart rate improvements, and improved vascular function.
Commenting on the results, Harry Rice, PhD, VP of regulatory & scientific affairs for the Global Organization for EPA and DHA Omega-3s (GOED), told us: "Scientists have known for a long time that prolonged undue stress can wreak havoc on one's health, both mentally and physically.
"The present research suggests that fish oil intake may blunt the ability of mental stress to create chaos with one's physical health. To the extent that the results can be extrapolated further downstream, this could mean the attenuation of disease initiation or progression.
"For maintenance of health, this would be monumental."
Led by Jason Carter, the researchers recruited 67 people with normal blood pressure and submitted them all to a five-minute mental stress protocol at the start of the study and eight weeks later, during which they were randomly assigned to received either the fish oil supplements or placebo.
“The fish oil dosage and the selection of olive oil as the placebo were based on a literature review of double-blinded, placebo-based studies examining the influence of fish oil on blood pressure in humans,” they explained.
Results showed that the fish oil supplements blunted heart rate reactivity to mental stress, and the total muscle sympathetic nerve activity. No effects were observed on blood pressure, added Carter and his co-workers.
“These findings support and extend the growing evidence that fish oil may have positive health benefits regarding neural cardiovascular control in humans,” wrote the researchers.
“Future studies might examine the influence of longer duration (i.e., chronic) fish oil supplementation on neural cardiovascular reactivity to mental stress, with a particular focus on aged and/or diseased populations.”
The study was funded by a grant from the National Heart, Lung, and Blood Institute.
Source: American Journal of Physiology - Regulatory, Integrative and Comparative Physiology
Volume 304, Number 7, Pages R523-R530, doi: 10.1152/ajpregu.00031.2013
“Fish oil and neurovascular reactivity to mental stress in humans”
Authors: J.R. Carter, C.E. Schwartz, H. Yang, M.J. Joyner