There are several red flags for readers to be aware of in trying to understand this unpublished study (presented as a conference poster) looking into possible dietary influences on bipolar disorder. Mainly, this is a very small study, of limited duration, in which supportive data are not provided, and some key study design limitations are not discussed.
On a very positive note, the news release does a good job of making it clear the results need to be validated before dietary advice can be incorporated into the treatment of bipolar illness.
This news release serves as a good reminder that:
Exploring dietary treatments for any kind of illness holds great appeal for many reasons, not the least of which is — if proven effective — it could give patients a greater role in participating in their own care. Avoiding drug approaches also has many potential benefits.
But these studies are very often observational, making it hard to prove a cause-and-effect relationship between certain foods and targeted health outcomes.
This release does an exemplary job of using cautious language and providing important context from an independent source, a practice we’ve recently encouraged EurekAlert! and other wire services to adopt.
The study investigated three interventions: 1) A combination treatment of over a dozen “mitochondrial enhancing agents” (including N-acetylcysteine, or NAC); 2) NAC alone; 3) placebo.
NAC is the only intervention that is routinely used as a treatment. Its cost is not included. According to Amazon.com a 600 mg tablet costs roughly $0.10 – $0.30 (but the dosage used in the study is not mentioned).
The lead author is quoted as saying:
“We found that people who had a better-quality diet, a diet with anti-inflammatory properties, or a lower BMI (body mass index), showed better response to add-on nutraceutical treatment than those who reported a low-quality diet, or a diet including foods that promote inflammation, or who are overweight”
The release identifies a “good” diet as having “lots of fruits and vegetables” versus a “poorer quality diet had more saturated fat, refined carbohydrates, and alcohol.”
The foods considered anti-, or pro-inflammatory, are not identified. Nor are the “add-on neutraceuticals.” The BMI criteria for being overweight is not mentioned. Providing this information would have made it easier for readers to place the study’s benefits in context.
The harms of NAC, according to Memorial Sloan Kettering Cancer Center, listed here, are not mentioned.
The news release describes the parameters of the research, and significantly, is to be commended for including some limitations of the study and for noting that the results need to be replicated in a larger study. An outside expert is quoted:
“This is interesting work, which holds out the possibility that patients with Bipolar Disorder may benefit from a balanced diet. However, it is an early study, and we need more research before we can think whether this might affect clinical practice”.
Other limitations of the research we observed is that it is unpublished (ie. unvetted by independent experts); very small (only 133 people completed the study); the duration of follow-up is less than half a year; and dietary information was gleaned from self-reporting (which can be quite unreliable).
No disease mongering. The release provides context on what constitutes bipolar disorder.
According to the National Institute of Mental Health “an estimated 4.4% of U.S. adults experience bipolar disorder at some time in their lives.”
Study funders are noted on the sidebar of the hosting service, EurekAlert! It would be helpful to include that information in the body of the news release as well.
Careful review of the author disclosures included in the study reveal no significant conflicts of interest.
Bipolar disorder is fairly well-defined in the release, and it’s mentioned “there is a great need for better treatments for the depressive phase.” However, current alternative treatments such as medications, light therapy or electroconvulsive therapy (ETC) in severe cases are not mentioned.
The release suggests “nutraceuticals,” including the anti-inflammatory amino acid n-acetylcysteine (NAC) are potentially helpful. NAC is widely available in both prescription and over-the-counter formulations.
The release states that if the results can be replicated in a larger trial then it would show that diet and weight affect treatment for bipolar disorder.
However, this doesn’t appear to be novel research since there are a host of dietary studies in the bipolar literature. Researchers are looking at dietary interventions in more controlled ways in bipolar disorder, depression and dementia.
A major strength of this news release is that it mentions the preliminary nature of the study results on three occasions, including once by an independent source NOT affiliated with the study (although his credentials should have been mentioned).