How Does Dietary Counselling Compare to More Conventional Mental Health Treatments?

In the last 7 years, there has been mounting evidence that diet change can improve symptoms of depression. (Teaser: I recently led the world’s first clinical trial of diet change for generalized anxiety disorder and the results are coming soon!) Multiple studies have reported a benefit of dietary counseling in a range of populations including people with self-reported depression(1), people with moderate-to-severe depression(2) and young men with depression(3). A key component of a research study is the comparison group. If we give all of the participants a treatment (like a drug, or a diet), and they improve, we can’t tell what might have happened if we had NOT given them the treatment. Would they have stayed the same or gotten better anyway due to other factors like the arrival of spring or positive events? If the whole group gets the treatment, we can’t tell. This is why research study have a control or comparison group. In the studies above, the comparison group was a social support intervention where participants had some social interaction with other people. While we know that social interaction is helpful, it’s not as helpful as the treatments that are typically offered to people with depression – medication and psychotherapy. Not surprisingly, in all 3 studies, the participants in the social support group experienced a small improvement in their depression symptoms and the participants in the nutrition group, experienced a larger improvement. In the SMILES study(2), which enrolled participants who all had moderate-to-severe depression, one quarter of the participants no longer met criteria for having depression at the end of the 12-week program.

While these results are impressive, it’s hard to draw comparisons about how effective different treatments are when the studies compare the new approach to treatments that aren’t meant to be very effective (like the social support interventions mentioned above). Well, one group of researchers recently published an exciting new study that helps us to understand how the effects of diet change compare to a more conventional mental health treatment(4). The CALM trail recruited people with depression and randomly assigned them to two groups. One group attended an 8-week online group program about lifestyle – this included advice on nutrition and exercise. The other group attended an 8-week online group cognitive behavioural therapy (CBT) program. What did they find? Both groups reported a decrease in depression symptoms and there was not a significant difference between the two. They also conducted a cost-analysis and again found that the two programs had a similar cost savings. While this study is the first of its kind, it suggests that the benefit of lifestyle change could be similar to the benefit of CBT.

Does this mean that we should use lifestyle change instead of psychotherapy? Heck no!! Because we have decades of research telling us that psychotherapy is effective, it suggests that lifestyle change is also effective. Not all people experiencing depression are open to doing psychotherapy and others would like to but don’t have access because of barriers. Diet and lifestyle counselling might be a good option for these individuals. If people are interested in both, there is no reason that these approaches can’t be combined! In my 12 years of practice, some of the patients who I have seen make the best recoveries from depression were working with me while working with a psychotherapist at the same time. The take away: people experiencing depression can benefit from both psychotherapy and lifestyle therapies.

1. Parletta N, Zarnowiecki D, Cho J, Wilson A, Bogomolova S, Villani A, et al. A Mediterranean-style dietary intervention supplemented with fish oil improves diet quality and mental health in people with depression: A randomized controlled trial (HELFIMED). Nutr Neurosci. 2019 Jul;22(7):474–87.

2.  Jacka FN, O’Neil A, Opie R, Itsiopoulos C, Cotton S, Mohebbi M, et al. A randomised controlled trial of dietary improvement for adults with major depression (the “SMILES” trial). BMC Med. 2017 Jan 30;15(1):23.

3.  Bayes J, Schloss J, Sibbritt D. The effect of a Mediterranean diet on the symptoms of depression in young males (the “AMMEND” study): A Randomized Control Trial. Am J Clin Nutr. 2022 Apr 20;

4.  O’Neil A, Perez J, Young LM, John T, Turner M, Saunders D, et al. Clinical and cost-effectiveness of remote-delivered, online lifestyle therapy versus psychotherapy for reducing depression: results from the CALM non-inferiority, randomised trial. Lancet Reg Health - West Pac. 2024 Jul;101142.