Eating a healthy diet can reduce stress and improve mood, a major review has found. British researchers have concluded that eating well is good for mental health as well as the waistline.
Experts from the universities in Birmingham, Edinburgh and Sweden found that diet improves mental resilience and protects against anxiety and depression.
‘Accumulating evidence provides support of the existence of direct relationships between nutrition, stress susceptibility, mental health and mental function,’ they wrote in the European Neuropsychopharmacology journal.
The researchers, who trawled all existing evidence, said the studies conducted to date confirmed the link between food and mental health – but they said scientists are yet to establish exactly which foodstuffs have the greatest impact, or why.
The strongest evidence suggests eating lots of vegetables improve mental and emotional well being.
And the Mediterranean diet – rich in olive oil and fish – has also been shown to be beneficial.
But the researchers said there is a dearth of studies into other food types.
Scientist and study leader Professor Suzanne Dickson, of Gothenburg and Edinburgh, said: ‘We have found that there is increasing evidence of a link between a poor diet and the worsening of mood disorders, including anxiety and depression. However, many common beliefs about the health effects of certain foods are not supported by solid evidence.”
Her team found there are some areas where the link between diet and mental health is firmly established, such as how a high – fat and low-carbohydrate or ketogenic – diet helps epileptic children. Vitamin B12 deficiency is also known to worsen fatigue, poor memory, and depression.
The researchers also found good evidence that a Mediterranean diet has mental health benefits such as protecting against depression and anxiety.
However, for many foods or supplements, the evidence is inconclusive, as for example with the use of vitamin D supplements, or with foods associated with ADHU or autism. ‘With individual conditions, we often found very mixed evidence.” Said Professor Dickson.
“With ADHD, for example, we can see an increase in the quantity of refined sugar in the diet seems to increase ADHD and hyperactivity, whereas eating more fresh fruit and vegetables seems to protect against these conditions. But there are comparatively few studies, and many of them don’t last long enough to show long-term effects.’
The researchers also found that while certain foods are associated with mental health scientists are unsure why. The strongest theories so far are linked to the idea of the “brain-gut axis’ – an emerging idea that the brain is linked directly to the digestive system.
Professor Dickson said: “We also need to consider genetics. Subtle differences in metabolism may mean that some people respond better to changes in diet than others. We need more studies on the long-term effects of everyday diets.’
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