There's little doubt that fish and their special omega 3 fatty acids help deter cardiovascular disease.
The American Heart Association recommends eating at least two servings of fish a week … especially salmon, sardines, tuna, and other fatty varieties rich in omega 3s.
Omega-3s moderate blood levels of triglycerides and inflammation – two key drivers of cardiovascular disease (CVD) – and exert beneficial effects on blood pressure and heart rhythms.
In addition, it's likely that omega-3s exert as yet unknown “nutrigenomic” effects on people's genes.
Until now, no one had ever examined the ways in which omega-3s might moderate people's physiological reactions to stress … some of which promote CVD or are or suspected of doing that.
Does stress promote cardiovascular disease?
This question has provoked substantial research … and recent evidence reviews suggest the answer is a qualified “yes”.
According to the Australian authors of one literature review, there exists “strong and consistent evidence” that depression and social isolation promote CVD (Kuper H et al. 2002).
They also estimated that these psychological factors promote CVD about as strongly as traditional risk factors such as smoking, inflammation, elevated blood fats, and hypertension.
Surprisingly, the Aussie team found no persuasive evidence that CVD is caused by chronic personal or work-related stresses, Type A behavior, hostility, anxiety, or panic disorders.
Now, a multi-center scientific team reports new clinical evidence that fish oil might counteract the detrimental effects of mental stress on cardiovascular health.
Omega-3s may aid hearts by easing reactions to stress
A placebo-controlled clinical trial was led by Jason R. Carter of Carter of the Michigan Technological University (MTU).
He and his MTU colleagues collaborated with scientists from New York Medical College, Michigan Technical College, and the Mayo Clinic (Carter JR et al. 2013).
They hypothesized that fish oil would blunt the blood pressure, heart rate (HR), and muscle sympathetic nerve activity (MSNA) response to mental stress, and/or moderate the increased forearm and calf blood flow associated with mental stress.
At the beginning of the eight-week trial, 67 adult volunteers underwent a battery of cardiovascular-function tests, including heart rate, blood pressure, MSNA (muscle sympathetic nerve activity), and blood flow through the forearm and calf.
(MSNA is part of the “fight or flight” response to stress. Increased MSNA is a response to congestive heart failure, and eventually leads to further worsening of cardiac function.)
These tests were performed under two different scenarios:
Both groups had comparable results when their cardiovascular functions were tested when the subjects were at rest.
The study subjects were divided into two roughly equal groups, each assigned to a different supplement regimen for eight weeks:
The study was “blind”, so none of the volunteers knew which supplement they were taking.
After eight weeks, the subjects repeated the same cardiovascular function tests.
Compared with the volunteers who took olive oil, those who took fish oil had milder responses to mental stress.
The fish oil group displayed advantages, including milder heart rate, MSNA, and calf blood flow reactions to mental stress … but no change in their blood pressure response to mental stress.
As the researchers wrote, “These findings support and extend the growing evidence that fish oil may have positive health benefits regarding neural cardiovascular control in humans.” (Carter JR et al. 2013)
The results might eventually help doctors prevent heart disease in select populations.
Presumably, the people who'd benefit most would be those under special stresses … such as caregivers, people in high-stress jobs, and people with type A personalities plus anger issues.
“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 ...” (Carter JR et al. 2013)
Future studies might focus on the effects of taking fish oil for longer time periods and examining this effect on older people, or people with cardiovascular disease.
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