Written by Greg Arnold, DC, CSCS. This study shows that omega-3 fatty acids found in fish oil reduced nervous system activity during a mental stress test by 60.7% after 8 weeks, which leads to decreased risk for high blood pressure and cardiovascular disease.
Research supporting the heart-healthy effects of omega-3 fatty acid includes their ability to maintain healthy levels of triglycerides (1), decrease the rate at which plaque forms in blood vessels (2), and helping maintain a healthy blood pressure (3). These three benefits all contribute to helping omega-3 fatty acids fight against heart disease, which causes 1 out of every 4 deaths each year. One heart attack occurs every 34 seconds, causing one death every minute and costing our healthcare system $108.9 billion each year (4).
Now a new study (5) suggests that omega-3 fatty acids may also benefit mental health by affecting the nervous system. In the study, 67 patients between the ages of 23 and 25 with normal blood pressure (below 140/90 mmHg) were given either fish oil (9 grams of fish oil per day (1.6 g EPA (eicosapentaenoic acid), 1.1 grams DHA (docosahexaenoic acid) = 34 subjects (24 men, 10 women)) or placebo (olive oil = 33 subjects (22 men, 11 women) for 8 weeks.
Before and after the study, the subjects had their blood pressure taken. They also underwent a mental stress test consisting of continuously subtracting the number 6 or 7 from a two or three-digit number verbally and were encouraged by an investigator to subtract as quickly as possible. The subtraction number (6 or 7) was randomized.
Immediately after the mental stress test, subjects were asked to rate their perceived stress using a standard 0–4 perceived stress scale (6). To measure nervous system activity during the mental stress test, the subjects were connected to an electrocardiogram to measure their heart rate. Sensors were connected to their calf muscles by a process called microneurography, which assesses the part of the nervous system dealing with “fight or flight” called the sympathetic nervous system.
After 8 weeks, researchers found a significant effect of fish oil supplementation in calming nervous system activity. Specifically, sympathetic nervous system activity during the mental stress test decreased by 60.7% after 8 weeks (9,900 to 3,900 arbitrary units) compared to a 3.3% decrease in the control group (6,200 to 6,000 arbitrary units, p = 0.029). Fish oil also significantly decreased heart rate during the mental stress tests, with a 20% decline observed (20 to 16 beats per minute) compared to no change in the placebo group (p = 0.002). No significant differences were seen between the two groups regarding blood pressure or perceived levels of stress by the subjects during the mental stress test.
Citing research showing that mental stress increases nervous system activity and the risk for high blood pressure and possibly cardiovascular disease (7), the researchers concluded that “fish oil may have positive health benefits regarding neural cardiovascular control in humans and suggest important interactions between fish oil and psychological stress that may contribute to [the onset of ] disease.”
Source: Carter, Jason R., et al. “Fish oil and neurovascular reactivity to mental stress in humans.” American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 304.7 (2013): R523-R530.
© 2013 the American Physiological Society
Posted July 30, 2013.
Greg Arnold is a Chiropractic Physician practicing in Hauppauge, NY. You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com
References:
- Harris WS. n-3 fatty acids and serum lipoproteins: human studies. Am J Clin Nutr 65: 1645S–1654S, 1997.
- Eritsland J, Arnesen H, Gronseth K, FjeldNB, Abdelnoor M. Effect of dietary supplementation with n-3 fatty acids on coronary artery bypass graft patency. Am J Cardiol 77: 31–36, 1996.
- Morris MC, Sacks F, Rosner B. Does fish oil lower blood pressure? A meta-analysis of controlled trials. Circulation 88: 523–533, 1993.
- “Heart Disease Facts” posted on the CDC Website.
- Carter JR. Fish oil and neurovascular reactivity to mental stress in humansAm J Physiol Regul Integr Comp Physiol 304: R523–R530, 2013. First published February 13, 2013; doi:10.1152/ajpregu.00031.2013.
- Callister R, Suwarno NO, Seals DR. Sympathetic activity is influenced by task difficulty and stress perception during mental challenge in humans. J Physiol 454: 373–387, 1992.
- Matthews KA, Katholi CR, McCreath H, Whooley MA, Williams DR, Zhu S, Markovitz JH. Blood pressure reactivity to psychological stress predicts hypertension in the CARDIA study. Circulation 110: 74–78, 2004.
