Depression is fast becoming one of the most common chronic conditions in Western countries, and it’s been predicted that its incidence is likely to continue to rise.
The World Health Organisation (WHO) has predicted that by the year 2020, in developed regions depression will become the highest-ranking cause of burden of disease.
According to the WHO:
’Mental and behavioural disorders are common, affecting more than 25% of all people at some time during their lives. They are also universal, affecting people of all countries and societies, individuals at all ages, women and men, the rich and the poor, from urban and rural environments.’
The age of onset of depression is said to be declining, and the rates are also increasing! So investigating factors that will have a beneficial effect on mental health is becoming an increasingly important area of study.
With this in mind, it was with great interest last week that I tuned in to a fascinating webinar presentation by researcher Dr Felice Jacka, an NHMRC Research Fellow at Deakin University, Australia. Dr Jacka and her colleagues have been researching the relationship between dietary quality and mental health, and their research has revealed some interesting findings.
For example, a research study by this group published last year looked at the association of Western and traditional diets with depression and anxiety in women. This study identified different dietary patterns by using a food frequency questionnaire to assess habitual dietary intake over a 12-month period. Results showed that a ‘traditional’ dietary pattern, consisting of vegetables, fruits, beef, lamb and wholegrains, was associated with a lower likelihood of depressive and anxiety disorders; whereas a ‘Western-pattern’ diet, largely comprising processed, fatty and sugary foods such as chips, processed meats, meat pies, white breads, hamburgers, sugar, flavoured milk, pizza and beer, was associated with a higher likelihood of psychological symptoms and disorders.
Other research was presented from prospective studies, which seems to indicate a relationship between diet quality and mental health.
My first thought was that people who are depressed may not have the desire or ability to shop, prepare and cook a healthy diet — so perhaps a poor diet is a result of the depression rather than a cause (reverse causality). However, it seems that the research to date suggests this is not the case. For example, a study that looked at the association between the Mediterranean diet patterns and the incidence of depression excluded depression cases diagnosed during the first two years of follow-up, and found that this strengthened the magnitude of the association with diet quality.
Depressive illness is influenced by genetic, hormonal, immunological, biochemical and neurodegenerative factors, according to Dr Jacka and her colleagues. It is thought that diet and nutrition may modulate the biological processes that underpin mental illness. However, it seems that there is no magic bullet and it is consuming a healthy, balanced diet, with minimal ‘junk’ food, that is important.
Dr Jacka’s research as been described as one of the most important studies of last year by Medscape, who commented that:
’Prevention is the Holy Grail of medicine. In the past decade, prevention of mental illnesses has become a topic of vast interest and relevance in the field of psychiatry research….
’…Jacka and colleagues’ results, although preliminary, are intriguing as they suggest the potential for broad and basic prevention of high prevalence mental disorders like depression and anxiety, with relevance for bipolar disorder and psychotic disorders in which both depression and anxiety are common.’
The next question to be answered is whether dietary intervention will improve mental health in those already diagnosed with depression, anxiety or bipolar disorder. A randomised controlled trial is about to commence that should give us the answers to this question in about three years’ time. I’ll certainly be keeping a close eye on the research as it is published.
In the meantime, it will benefit us all physically, and probably mentally as well, to have a wholesome and nutritious diet comprising lean meat, fish, wholegrains and plenty of fruits and vegetables.