This study is important for two reasons.
First - it shows that anxiety can be reduced in healthy young adults by supplementing their diets with the long-chain omega-3 fatty acids found in fish and seafood. These students did not have particularly high levels of anxiety to begin with, so to show a symptom reduction in this group is all the more impressive.
Second - it shows a clear link between the observed reductions in anxiety and down-regulation of the immune system. This is consistent with previous work suggesting that the well-known anti-inflammatory effects of long-chain omega-3 may help to explain their benefits for stress, anxiety and depression.
For more details of this study, see:
Increasing omega-3 intake may lower both anxiety symptoms and proinflammatory cytokines in healthy young adults, new research suggests.
In a small randomized controlled trial of medical students, those who received omega-3 supplements for 3 months showed a 20% reduction in anxiety scores and a 14% reduction in stimulated interleukin 6 (IL-6) production.
According to the investigators, the study "provides the first evidence that omega-3 may have potential anxiolytic benefits for individuals without an anxiety disorder diagnosis."
"We were impressed by the magnitude of the anxiety effect and the evidence for its anti-inflammatory effects, suggesting that it might have broader benefits," lead study author Janice Kiecolt-Glaser, PhD, professor of psychiatry and psychology and S. Robert David Chair of Medicine at the Institute for Behavioral Medicine Research at Ohio State University College of Medicine (OSUMC) in Columbus, told Medscape Medical News.
She noted that the significant reduction in IL-6 is especially important because the young study population had low rates to begin with.
"So our findings could possibly be much more significant in a group that was older and had more health problems."
The study was published online July 19 in Brain, Behavior and Immunity.
Fish Oil Benefits the Body
"Chronic inflammation has been linked to a broad spectrum of health problems, including cardiovascular disease, stroke, and rheumatoid arthritis," write the researchers.
"Large population studies suggest that greater fish consumption may help control or protect against the onset of these and other inflammatory conditions," they add.
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are 2 key omega-3 polyunsaturated fatty acids (PUFAs) found in fish oil, which may also benefit mood.
In fact, previous research, including a study reported on last year by Medscape Medical News, has suggested that omega-3 can lower depressive symptoms in patients diagnosed as having clinical depression.
Because both depression and anxiety have been found to increase the production of proinflammatory cytokines, the current investigators hypothesized that giving omega-3 PUFA supplementation to healthy subjects would lead to a decrease in this production.
Secondary outcome measures were lowered anxiety and depressive symptoms, as well as lowered negative mood symptoms associated with taking stressful exams.
A total of 68 first- and second-year medical students (56% male; mean age, 23.65 years) were enrolled and randomized to receive 3 times daily either omega-3 supplement capsules (consisting of 2085 mg of EPA and 348 mg of DHA, n = 34) or fish-flavored placebo capsules (n = 34) for 12 weeks.
"We chose the 7:1 EPA/DHA balance because of evidence that EPA has relatively stronger anti-inflammatory and antidepressant effects than DHA," explain the investigators.
"The supplement was probably about 4 or 5 times the amount of fish oil you'd get from a daily serving of salmon," added coauthor Martha Belury, PhD, RD, professor of human nutrition at Ohio State University, in a release.
All participants were interviewed 6 times, and serial blood samples were scheduled to be taken during lower-stress days and on the days before major exams.
In addition, the Center for Epidemiological Studies Depression Scale and Beck Anxiety Inventory were administered at all visits.
Reduced Anxiety, Cytokines
Results showed no significant differences between stress and nonstress days across all outcomes for either group.
"Thus, the ability of omega-3 supplementation to dampen stress response could not be tested," write the researchers.
They note that this was probably due to a sudden change in the medical school's curriculum. Instead of distributing the major tests during a 3-day period, as done in the past, the exams were given throughout the year.
"This group was notably unstressed, which was a severe disappointment and a study limitation. We just didn't get the stress effect we had expected," said Dr. Kiecolt-Glaser.
Still, the treatment group showed a significantly greater reduction in anxiety symptoms at 20% than did the placebo group (P = .04). They also had a greater decrease in their amounts of stimulated IL-6 production (0.15 units lower, P = .04).
"Anything we can do to reduce cytokines is a big plus in dealing with the overall health of people at risk for many diseases," said coauthor Ron Glaser, PhD, professor of molecular virology, immunology, and medical genetics at OSUMC.
There were no significant changes in depressive symptoms for either group."Again, this was not a depressed group, and without more severe depression, you may not see an effect," said Dr. Kiecolt-Glaser.
"Overall, that both anxiety and inflammation were altered is notable, especially in a group that was not clinically anxious," she added.
Even so, the investigators are not yet ready to suggest that everybody should start taking fish oil pills. "It may be too early to recommend a broad use of omega-3 supplements throughout the public, especially considering the cost and the limited supplies of fish needed to supply the oil. Instead, people should just consider increasing their omega-3 through their diet," said Dr. Belury.
Dr. Kiecolt-Glaser reported that the investigators have just finished another trial that examined the effects of increasing omega-3 in a population between the ages of 40 and 85 years who have an average body mass index of 30.
Omega-3 for All Psychiatric Disorders?
"This study reveals 2 remarkable, clinically solid findings," Capt. Joseph R. Hibbeln, MD, acting chief, Section on Nutritional Neurosciences at the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health (NIH), Bethesda, Maryland, told Medscape Medical News.
The first, "which cannot be understated," is the reduction of anxiety scores in a normative population, said Dr. Hibbeln, who was not involved with this study.
"Many trials of omega-3 fatty acids in depression have confused the field because it's very difficult to reduce depression in people who don't have the disorder. And it's also very difficult to reduce anxiety in those who don't have clinically manifest anxiety," he explained.
"The second was that they probed the question of whether or not omega-3 fatty acids at least work in part through changes in the immune system and neural-immune interactions by measuring the effects of cytokine release in the patients' white blood cells ex vivo."
He noted that the "very marked decrease" in cytokine production in the treatment group was impressive.
"This is absolutely consistent with the hypothesis that one of the mechanisms of action for omega-3 fatty acids is not necessarily central but is through down-regulating the immune system. The study begs the question: is increased anxiety a manifest symptom of omega-3 fatty acid deficiencies? And their answer is yes."
Dr. Hibbeln said that the current 2010 US Department of Agriculture Dietary Guidelines recommend omega-3 PUFAs for the protection of heart disease and for pregnant mothers to prevent deficiencies in their offspring.
In 2006, the treatment committee for the American Psychiatric Association (APA), of which he was a member, issued recommendations that all patients with a psychiatric disorder should take at least 1 gram a day of omega-3 PUFAs to prevent the medical complications that often co-occur for them, such as cardiovascular disease and metabolic problems.
"This paper should be another signal that the practicing psychiatrist should follow the 2006 APA recommendations," concluded Dr. Hibbeln.