If you’re one of the many people across the globe battling against the symptoms of mild depression, you may be able to get relief by eating nutritious food or going on a weight loss diet.
That’s according to the results of a new study, published in Psychosomatic Medicine, which shows that you can significantly reduce the symptoms of non-clinical depression – like social withdrawal, sleeping difficulties and feelings of despair – by improving your diet.
The study, conducted by researchers from Australia, Brazil, Canada, Italy and the UK, analysed data from 16 randomised control trials involving almost 46,000 people with situational depression to determine the relationship between various dietary interventions and mood.
The results revealed that dietary improvements brought about by a weight loss, nutrient boosting or fat reduction diet helped to reduce the symptoms of a depressed mood in people who did not have a clinically-diagnosed psychiatric condition.
The study also shows that women who change their diet will see a greater improvement in the symptoms of anxiety and depression compared to men.
“This is actually good news,” says the study’s lead author, Postdoctoral Research Fellow in the NICM Health Research Institute at Western Sydney University, Dr Joseph Firth.
“The similar effects from any type of dietary improvement suggests that highly-specific or specialised diets are unnecessary for the average individual.
“Instead, just making simple changes is equally beneficial for mental health. In particular, eating more nutrient-dense meals that are high in fibre and vegetables, while cutting back on fast-foods and refined sugars, appears to be sufficient for avoiding the potentially negative psychological effects of a ‘junk food’ diet.”
Although the evidence showed that adopting a healthier diet could help overcome the symptoms of depression, there was no general or clear effect on anxiety.
The study also highlights that women who change their diet may see a greater improvement in the symptoms of anxiety and depression compared to men.
“We did see a trend for women to benefit specifically in terms of mental health outcomes than males.”
Dr Firth adds that although the study doesn’t identify why dietary improvements affect women and men differently, it could come down to “genuine biological issues or social factors, or it could be driven by [the fact] that there is a higher incidence of depression in women”.
“But once you are at a healthy weight, there’s no indication from this data that losing more weight would actually benefit your mental health in any way.”
All of the weight loss interventions in the study were conducted on overweight or obese participants.
Dr Firth explains the benefits of a weight loss diet on mild depression correlates with the amount of weight lost. “But once you are at a healthy weight, there’s no indication from this data that losing more weight would actually benefit your mental health in any way. In fact, it could have the reverse effect but we’ve not examined that.”
The study’s authors do not specifically explain why dietary interventions help to improve mood and depressive symptoms. However, they do hypothesise that dietary changes may affect the pathways that are implicated in mental health. For example, diet could impact inflammation in the body, the gut microbiota and oxidative stress.
The paper’s authors add that various vitamins, fatty acids, minerals and fibre consumed as part of a healthy diet could also impact the brain and help to improve mood.
“Given the prevalence of both poor diet and depression across the globe, more research on how these two are related could produce new understanding on how to improve population health.”
Depression is a global issue
Beyond Blue estimates that 45 per cent of people will experience a mental health condition in their lifetime and in any one year, around one million Australian adults have depression.
Across the world, depression is widespread. In Italy, where some data for the study was collected, depression is the most common mental disorder. About 1.3 million people (2.5 per cent of the population) suffered from current major depressive symptoms during the past two weeks, research released in 2018 states.
According to the new study, depressive disorders affect over 300 million people around the world. They are associated with unemployment, poor physical health and impaired social functioning.
“Thus, depressive disorders incur considerable burden not only for individuals, but also for society due to the high economic cost from lost productivity and demand on healthcare services,” reads the study.
Co-senior author and deputy director at NICM Health Research Institute, Professor Jerome Sarris explains that the study’s findings demonstrate the potential impact, which healthier diets could have on mental health across the nation.
“Given the prevalence of both poor diet and depression across the globe, more research on how these two are related could produce new understanding on how to improve population health,” says Prof Sarris.