Daily omega-3 use may not have major impact on mood, depression in late life

Daily use of omega-3 in older adults at risk for depression correlated with a slight increase in depressive symptoms while having no effect on mood, according to a randomized clinical trial published in JAMA.

“For many years, experts have recommended omega-3 supplements for reducing the recurrence of depression in some high-risk patients,” Olivia Okereke, MD, SM, of Massachusetts General Hospital, told Healio Psychiatry. “However, there are no guidelines related to the use of omega-3 supplements for preventing depression in the general population. We undertook this study to provide clarity in the issue.”

Researchers sought to ascertain whether omega-3 usage in older adults yielded any significant effect on risk for depression and mood. Okereke said she and her colleagues gave equal attention to the risk for developing clinical depression at any point and to overall mood scores for the duration of follow-up. The study used an approach called “universal prevention,” a method rarely utilized due to the large sample size it requires.

Okereke and colleagues conducted a randomized clinical trial involving 18,353 adults between November 2011 and March 2014, with continued randomized treatment through Dec. 31, 2017. They collected data from older adults (mean age, 67.5 years; 49.2% women) who participated in the Vitamin D and Omega-3 Trial-Depression Endpoint Prevention (VITAL-DEP) study, a supplementary study to a randomized trial of cardiovascular disease and cancer prevention that involved 25,871 participants.

In the trial, participants were split into two groups: 9,171 participants were given 1 g per day of omega-3, while 9,182 were given a placebo. Assessment for depression risk, depressive symptoms in need of intervention and mood scores were determined by answers given to the Patient Health Questionnaire (PHQ-8).

Within the overall trial group, 16,657 participants were found to be at risk for depression without previous diagnosis, with 1,696 shown to be at risk for recurrent depression after not having shown symptoms for the previous 2 years.

While a small increase in risk for depression was inside the statistical margin of significance, there was no harmful or beneficial effect of omega-3 on the overall course of mood during the roughly 5 to 7 years of follow-up, according to Okereke.

Okereke and colleagues concluded that the study did not yield a net benefit of long-term use of daily supplements for preventing depression or boosting mood, adding the study should serve as an illustration of why it is important to test questions using rigorous randomized clinical trial designs.

“Patients, physicians and other clinicians should understand that there are still many reasons for some people, under the guidance of their health care providers, to take omega-3 fish oil supplements,” Okereke said. “These supplements increasingly have been found to have benefits for cardiac disease prevention and treatment of inflammatory conditions, in addition to being used for management of existing depressive disorders in some high-risk patients. However, the results of our study indicate there is no reason for people in the general population to take omega-3 fish oil supplements solely for the purpose of preventing depression or for maintaining a positive mood.”