A healthy diet treats depression by changing the gut microbiome and reducing inflammation and oxidative stress, researchers say.
A healthy diet – especially the Mediterranean diet – can improve symptoms of depression, Australian researchers say.
The researchers said there was strong evidence that dietary interventions for depression such as the Mediterranean diet and the DASH – Dietary approaches to Stop Hypertension – diet also improved health outcomes for cardiovascular disease and diabetes.
“Therefore there is potential for dietary counselling to address both mental and physical health conditions in the same individual,” they said in a literature review in the Australian & New Zealand Journal of Psychiatry.
The evidence that diet is a risk factor for mental health problems and the large burden of cardiometabolic disease supports the use of dietary interventions to treat depression, they said.
“Given the high rates of cardiometabolic comorbidity in individuals with depression, this is a favourable approach because of its protective effects for metabolic syndrome and cardiovascular disease.”
One 2021 synthesis including more than 150,000 participants found that sticking to a healthy diet reduced the risk of depression.
The researchers said diet might affect mood through the gut microbiome, modulating inflammation, reducing oxidative stress and modulation of hypothalamic-pituitary-adrenal axis function.
Several studies have shown that the gut microbiome changes in people with clinical depression, and levels of some microbiome taxa correlate with symptom severity, they said.
“Some studies show adherence to a Mediterranean-style diet, vegetarian/vegan and DASH diet have been associated with lower levels of systemic inflammation.
“Conversely, increased intake of foods and nutrients characteristic of a Western-style diet, including foods high in sugar or saturated fat, can increase inflammatory markers.”
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The DASH diet focuses on fruit, vegetables, wholegrains, nuts, seeds, legumes, low- or no-fat dairy products and lean meat, low salt intake and increased foods rich in potassium, calcium and magnesium.
The researchers said it was critical to take a “weight-neutral approach” and focus on health behaviour change rather than on weight loss.
“Weight stigma and negative attitudes about one’s body weight and shape hinder positive changes, creates unnecessary pressure and can promote poor eating behaviour and low motivation.”
The researchers suggested that clinicians talk to patients about how a healthy diet can help manage depression, and how processed snack foods increase the risk of poor mental health.
“This must be delivered in a highly sensitive non-stigmatising fashion, as patients commonly experience shame around food, eating and body weight.”
The researchers suggested asking open questions such as whether the patient could describe a typical day’s food intake, how many meals and snacks were eaten each day and whether the patient cooked for themselves.
“Initiating a discussion around food and eating will also help to provide some understanding about an individual’s knowledge about nutrition and its importance to the individual,” they said.
The researchers suggested identifying any barriers to healthy eating including side effects of mental health conditions such as apathy, appetite changes or impaired memory.
“Clinicians are recommended to provide diet counselling in a sensitive manner, cognisant that many individuals experience shame and guilt when discussing weight and diet behaviours,” they said.
“Dietary information should be delivered in accessible, bite-size format, and take into consideration the individuals learning styles, baseline knowledge and beliefs, motivations, readiness to engage in sessions, and relevant lifestyle factors.”
Food insecurity may also play a role in how much access patients have to healthy food, they said.
The researchers recommended face-to-face consultations because they resulted in greater behavioural change and long-term results than telehealth appointments.
Telehealth helps patients with mobility issues or mood disorders access consultations, but “there is currently insufficient evidence that web-based interventions are as effective as face-to-face interventions”.
Australian & New Zealand Journal of Psychiatry, 4 December 2024
