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Omega-3 Fatty Acids Could Benefit People with Bipolar Disorder

A dietary intervention may help stabilize moods in people with bipolar disorder.

Key points

  • A diet rich in omega-3 fatty acids improved mood stability in subjects with bipolar disorder.
  • Dietary changes appear to be key; dietary supplements, such as fish oil capsules, may not provide the same benefit.
  • The balance between omega-3 and omega-6 fatty acids appears to underlie the benefits of a novel dietary intervention.

Nutritionists and cardiologists have been touting the benefits of omega-3 fatty acids for years, pointing to their anti-inflammatory and heart-protective effects.

The body needs fatty acids to carry out a variety of functions but cannot manufacture many of them. This means that we need to get them from the foods we eat. Seafood is rich in beneficial fatty acids and probably our most important dietary source. They are also available as dietary supplements.

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Eat More Fish

Increasing the intake of two particular fatty acids with the tongue-twisting names eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been shown to reduce the risk of cardiac death by 30-45% in people who have already had a heart attack. Exactly how they exert this benefit is a matter of controversy. However, their anti-inflammatory effect is thought to be important.

It turns out that EPA and DHA are important in brain functioning, too. They are important in modulating signaling within the brain. They also decrease a type of chemical damage to brain cells called “oxidative stress.”

Epidemiological studies have shown that in countries with high-seafood diets (like Japan) fewer people develop bipolar disorder. But clinical trials in which people with bipolar disorder took omega-3 supplements have shown disappointing results.

The Balance of Omega Fatty Acids May Be Key

A new study from a team of researchers from Penn State University and the University of North Carolina suggests that the reason for this might be that omega-3s can’t work their magic if levels of another group of fatty acids, the omega-6s are too high. Omega-6 fatty acids are found in corn oil and some other plant-based oils. The body needs omega-6s, too, but a high level of omega 6s in the body appears to cancel out some of the benefits of the omega-3s.

To test their theory that the omega-3/omega-6 ratio is what’s important, they enrolled subjects with bipolar disorder who were having symptoms and started half of them on a diet high in omega-3s and low in omega-6s (more seafood, less corn and soybean oil). The other half were given a control diet. The dietary interventions lasted 12 weeks. The patients continued on whatever medications they were already taking for their mood disorder.

The subjects were given a specially programmed smartphone that delivered a questionnaire to them twice a day. The subjects were asked to rate their levels of mood, energy, speed of thoughts, impulsive thoughts and actions, anxiety, irritability, and pain.

Also, the researchers measured blood levels of the different fatty acids to see whether the dietary intervention had the hoped-for effect on levels of omega-3s and omega-6s.

Day-to-Day Symptom Cycling Decreased After Dietary Intervention

The dietary intervention did indeed change fatty acid levels in the subjects in the intervention group. Levels of the two most important omega-3s, EPA and DHA, increased significantly. Levels of one omega-6 went down but another was unaffected.

Mood symptoms did indeed stabilize significantly in the intervention group. The subjects’ mood, energy, irritability, and pain showed a decrease in the day-to-day variability of these symptoms.

While encouraging, these results need to be interpreted with caution. Although the subjects on the special diet had significant decreases in the variability of their symptoms, the overall level of symptoms did not decrease significantly over the course of the study. Also, there was no significant difference in symptom levels between the intervention group and the control group. Only the day-to-day cycling of symptoms decreased in the intervention group.

Stability Is Key

Nevertheless, increased mood stability is the most important treatment target in treating bipolar disorder. In my own experiences of treating people with bipolar disorder, I've noticed that it’s only after the mood has started to stabilize that a steady improvement in overall mood is noticed by the patient (although family members often notice the improvement sooner). Often, especially in significantly ill patients, as these subjects were, it takes many months after mood and other symptoms begin to stabilize until the individual notices a significant overall improvement in mood. Since the study only lasted 12 weeks, it’s quite possible that continuing the diet longer would have led to overall symptom improvement.


Saunders EFH, Mukherjee D, Myers T, et al. "Adjunctive dietary intervention for bipolar disorder: a randomized, controlled, parallel-group, modified double-blinded trial of a high n-3 plus low n-6 diet." Bipolar Disorders, published online July 4, 2021. doi: 10.1111/bdi.13112.

Russo, L. "Dietary omega − 6 and omega − 3 polyunsaturated fatty acids: From biochemistry to clinical implications in cardiovascular prevention." Biochemical Pharmacology 77: 6 (2009) 937-946. doi: 10.1016/j.bcp.2008.10.020.