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A Diet for Bipolar Disorder

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The first clinical trial of a modified diet for bipolar disorder in this daily dispatch from the International Society for Bipolar Disorders 2020 conference.

Published On: 6/30/2020

Duration: 7 minutes, 50 seconds


This week we’re podcasting DAILY from the International Society for Bipolar Disorders 2020 conference, where we’ve been scouring the virtual halls for all that is practical and newsworthy. The yield is high so tune in for a new episode every day. Today: unpublished results on a new diet for bipolar disorder.

Welcome to the Carlat Psychiatry Podcast, keeping psychiatry honest since 2003. I’m Chris Aiken, the editor in chief of the Carlat Report. And I’m Kellie Newsome, a psychiatric NP and a dedicated reader of every issue.

Erika Saunders and colleagues from the University of Pennsylvania-Hershey reported on preliminary results from a landmark trial: The first dietary treatment of bipolar disorder. The diet she used has already been successfully tested in migraines and epilepsy, and to understand it you need to know the difference between omega-3 and omega-6 fatty acids. Both of these have important roles in health and brain function, so neither is good or bad –it’s the balance that matters.

Specifically, it’s healthier to have more omega-3 than omega-6, but in the typical Western, that balance is out of whack: There are 14 to 25 times more omega-6 fatty acids than omega-3 fatty acids. The problem is made worse for people with bipolar disorder who don’t metabolize these fatty acids like the average person. So Dr. Saunders speculated that raising omega-3 and lowering omega-6 might improve mood in bipolar patients. We already know that omega-3 helps bipolar and depression as the popular supplement fish oil, which has proven effective in half a dozen meta-analyses, albeit with a small effect size. What we’ve never seen is how a dietary approach will work, and what would happen if omega-6 was intentionally lowered. Both of these are “essential” fatty acids, meaning the body can’t make them and needs a dietary source, and both play a role in brain development.

Mood stabilizers actually lower omega-6 levels, and omega-6 may cause depression by promoting inflammation (while omega-3 is anti-inflammatory). This was a RCT DB trial of 82 patients with bipolar disorder that compared two diets:

The treatment diet was high in omega-3, low omega-6. The other group was given omega-3 and 6 in a ratio that reflects the usual American diet. One thing in that design sets it apart from other studies in nutritional psychiatry. Usually patients know if they’re getting the dietary intervention, but in this study both groups were taught to eat a scientifically designed diet, which improves the double blind. And these diets were very controlled. Not only did they have guidance from dieticians, they were also given much of the food they ate, such as snacks that were carefully calibrated to have the intended ratios of omega 3 and 6.

This was a small study of 82 patients, 30% of whom dropped out, with equal drop-out rates in both arms. They were mainly white, in their early 40’s, and equal M:F ratio. About half were unemployed. The average MI was 30. The outcome measure was unique – subjects rated their mood daily on a smart phone using a simple visual analogue scale. They rated 7 items: mood, energy, thoughts, impulsivity, anxiety, irritability, and physical pain. They measured pain because omega-6 can increase prostaglandins which are associated with increased pain.

The primary outcome was the degree that mood, energy, and impulsivity varied day today. The results were mixed – positive for variability in mood and energy, but negative for variability in impulsivity, which actually improved in the control group. There was also no difference in an important secondary measure: the change in average mood measures from start to 12 weeks. This is an ongoing study, with plans to follow these patients for an entire year. We should know a lot more at that point, as the authors are gathering a truckload of biomarkers related to the diet, including monthly stool cultures to look for changes in the microbiome, blood tests for inflammatory markers, actigraphic measures of movement, and even cerebral spinal fluid. The Bottom Line ? – (“well” – ) we know that a healthy diet helps depression, but we don’t yet know which ingredients are the most important. This study is testing the idea that the omega-3 to 6ratio matters in bipolar disorder, and the results are too preliminary to draw conclusions at this time.

But short of that we already have a diet that’s ready for prime time in depression: the Mediterranean diet. And from what we know about bipolar disorder this diet should work there as well. The Mediterranean approach discourages the main foods that are driving the omega-6 overload in society: processed snacks, fast foods, cakes, fatty meats, and cured meats. And it’s proven effective in 3 controlled trials of depression with moderate to large effect size. This diet does have some healthy foods that are high in omega-6: nuts, seeds, avocados, and tofu – but worry not, those have a healthy balance of omega 3 as well. It’s the junk food that’s causing the problem. We covered the Mediterranean diet last yearn an interview with the lead investigator, Felicia Jacka. Listen to our 6/3/19 podcast or check out our May 2019 issue ─ it breaks down the specific food recommendations, as Dr Jacka’s team altered the Mediterranean diet to emphasize brain-friendly ingredients and make it easier for people with depression to follow.

Tune in tomorrow for new findings on an anti-inflammatory medication in bipolar depression. We’ll have more updates in our print issue, including unpublished results on a new medication for bipolar depression and a full review of the modafinils in bipolar disorder. We’re trying out a new format this week by bringing you shorter nuggets in daily episodes. And maybe we should keep it daily. If you like it that way, let us know by leaving a review in your podcast store.

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