Omega-3 fish oil helps prevent heart disease. We've known that for many years. Now new research shows it may stave off depression as well.
A recent study in the Journal of Clinical Psychiatry found that people with depression reduced their levels of depression by about 30 percent in eight weeks by taking a high-potency fish oil supplement.
That effect makes the fish oil more effective than selective serotonin reuptake inhibitors, better known as SSRIs, such as Prozac.
Half of the 432 participants in the study — the largest ever conducted on the effect of omega-3 fatty acids on depression — took three capsules a day of OM3 Emotional Balance, an over-the-counter dietary supplement that contains omega-3 fatty acids. The three capsules contained a total of 1,050 milligrams of EPA (eicosapentaenoic acid), the fatty acid in fish oil that is thought to have an effect on depression, along with 150 milligrams of DHA (docosahexaenoic acid). (Although omega-3 fatty acids are available in flax seeds, flax oil, walnuts and other nonfish sources, these contain primarily ALA, or alpha-linolenic acid, rather than EPA and DHA.)
The other half of the study group took a placebo.
Initial results showed little difference between the two groups, but upon closer analysis the researchers found that participants who suffered from depression only — without an accompanying anxiety disorder — responded robustly to the treatment.
It's worth noting that fish oil to some degree impedes blood clotting, which is a good thing for hearth health. But people taking blood thinners should consult with their doctor before taking fish oil. (You should always inform your doctor about all supplements you take, and the dosages.) But the three daily capsules of OM3 taken by participants in the study is still within the range of safety, according to lead author Dr. Francois Lesperance of the University of Montreal.
"I do not think that there are risks with less than 3 grams per day (of omega-3 fish oil)," he said.
Some antidepressants have side effects severe enough to cause some people to stop taking them, an important point noted by the study's authors.
"It is clear that there is a need for additional therapeutic options that represent alternatives to standard antidepressants," they wrote. "Omega-3 fatty acid supplements may provide such an option."
The researchers hope to conduct another study comparing omega-3 supplements directly with antidepressant medications.
The study was funded by a grant from Isodisnatura, the French company that manufactures OM3 Emotional Balance, but other research has also found that omega-3 fish oil counteracts symptoms of depression.
Alan C. Logan of the Integrative Care Centre of Toronto wrote a paper in 2004 titled "Omega-3 Fatty Acids and Major Depression" for the journal Lipids in Health and Disease. At the time, the research was divided: Some studies found that omega-3 fatty acids alleviated depression, while others found no effect.
But that has changed.
"A recent review of all research on the subject found 13 studies that support a positive association between omega-3s and depression, and six that showed no effect," Logan said. "So they're 2-to-1 in favor at this point. We're starting to see some agreement forming on this subject."
Some of the earlier disagreement resulted, he believes, from wide variation in dosage, especially the amount of EPA consumed.
"Evidence suggests that EPA appears to have the edge when it comes to alleviating depressive symptoms," Logan said. "One study used various dosages of EPA — 1,000, 2,000 and 4,000 — along with a placebo. It turned out that 1,000 milligrams of EPA seemed to have the greatest effect."
How does EPA affect depression?
Like Lesperance at the University of Montreal, Logan suspects that EPA reduces inflammation in the brain, possibly by lowering levels of cytokines, the immune system molecules that promote inflammation.
"In depression, quite typically there's an elevation in cytokines," Logan said. "The fact that omega-3s might influence that pathway is certainly a fertile area for research."
Over-the-counter fish oil capsules all contain omega-3 fatty acids, but the ratio between EPA and DHA may be important for elevating mood, according to Logan.
"The standard fish oil supplement contains 1 gram (of omega-3 fatty acids), with an 18-to-12 ratio," he said. "That means that of the 1,000 milligrams, 18 percent, or 180 milligrams, is EPA, and 12 percent, or 120 milligrams, is DHA. For general health purposes that might be enough, but to affect depression, you'll have to take a lot of capsules."
Some companies, however, have started producing capsules containing 500 milligrams of EPA.
"These capsules are available in health food stores and pharmacies," Logan said. "If you take two to four capsules a day, you're there."
Tom Valeo writes frequently about health matters. He can be reached at firstname.lastname@example.org.