Diet quality can affect many aspects of one's physical health and psychological well-being. New research investigates whether or not these factors can also affect the effectiveness of treatments for mood disorders—particularly bipolar.

The moods of people who have bipolar disorder fluctuate between two extremes.

These are the "highs," during which the person feels euphoric and may engage in dangerous behaviors, and the "lows," characterized by depression and lethargy.

Since two opposite mood extremes characterize this disorder, it is often difficult to treat both the "highs" (or "manic episodes") and the "lows" (or "depressive episodes") with the same efficacy.

New research presented at the European College of Neuropsychopharmacology congress, held in Barcelona, Spain, now suggests that weight and dietary habits may influence how effective treatments for bipolar disorder actually are.

In particular, a healthful diet may aid therapy for depressive episodes, note the study authors. They also explain that, conversely, a poor diet could contribute to heightened inflammation, which may have a negative impact on a person's symptoms.

"If we can confirm these results, then it's good news for people with bipolar disorder, as there is a great need for better treatments for the depressive phase of bipolar disorder," states lead researcher Melanie Ashton, from Deakin University in Geelong, Australia.

The team comprised scientists from numerous academic and research institutions across Australia, Germany, and the United States.

How diet may impact therapy results

Ashton and colleagues conducted a clinical trial for which they recruited 181 participants, of whom 133 provided all the data necessary for the final analysis. All the participants experienced bipolar depression, which is the depressive phase of bipolar disorder.

For a period of 16 weeks, the team randomly allocated all the participants to receive one of three types of treatment:

• a mix of nutraceuticals (or natural nutrients sometimes used as alternatives to drugs and that may help treat or prevent chronic diseases), including the anti-inflammatory substance n-acetylcysteine (NAC)
• only NAC
• a placebo

The investigators administered these treatments alongside the participants' normal medication for bipolar disorder.

At the start of the trial, the team also collected relevant information from the volunteers, including their BMIs, measures of depression, and to what extent they were able to function normally on a day-to-day basis.

The researchers assessed the volunteers' progress every 4 weeks—including 4 weeks after the cessation of the experimental treatment. They also asked them to answer questionnaires that evaluated dietary habits.

This allowed them to give scores to each participant depending on how healthful their regular diets were.

Good-quality diets included high consumption of fruit and vegetables, whereas poor diets relied on food high in saturated fats and refined carbohydrates, as well as excess alcohol consumption.

Ashton and her team categorized healthful diets as anti-inflammatory and poor-quality diets as pro-inflammatory, based on their contents.

"We found that people who had a better-quality diet, a diet with anti-inflammatory properties, or a lower BMI, showed better response to add-on nutraceutical treatment than did those who reported a low-quality diet, or a diet including foods that promote inflammation, or who were overweight."

–Melanie Ashton

The investigators believe that, if these results could be replicated in larger clinical trials, specialists may want to start handing out dietary advice to people diagnosed with bipolar disorder.

Ashton emphasizes the necessity of repeating this study, saying, "This is a randomized, controlled trial, but what we found were exploratory outcomes; in other words, it wasn't the main result that we were testing."

"Our result is statistically significant, but because the study wasn't specifically designed to test the effect of diet quality, inflammatory diets, and BMI on drug response in general," she explains, "it is necessary to see the work replicated in a larger study before any firm conclusions can be formed."