Research suggests that while healthy diets can reduce the risk or severity of depression, unhealthy diets may increase the risk.
Of course, we all all indulge from time to time but unhealthy diets are those that contain lots of foods that are high in energy (kilojoules) and low on nutrition. This means too much of the foods we should limit:
• processed and takeaway foods
• processed meats
• fried food
• butter
• salt
• potatoes
• refined grains, such as those in white bread, pasta, cakes and pastries
• sugary drinks and snacks
Many New Zealanders consume a lot of junk food a week, and far fewer serves of fibre-rich fresh food and wholegrains than recommended. This leave us overfed, undernourished and mentally worse off.
Having a healthy diet means consuming a wide variety of nutritious foods every day, including:
• fruit (two serves per day)
• vegetables (five serves)
• wholegrains
• nuts
• legumes
• oily fish
• dairy products
• small quantities of meat
• small quantities of olive oil
• water
This way of eating is common in Mediterranean countries, where people have been identified as having lower rates of cognitive decline, depression and dementia.
In Japan, a diet low in processed foods and high in fresh fruit, vegetables, green tea and soy products is recognised for its protective role in mental health.
How does healthy food help?
A healthy diet is naturally high in five food types that boost our mental health in different ways:
Complex carbohydrates found in fruits, vegetables and wholegrains help fuel our brain cells. Complex carbohydrates release glucose slowly into our system, unlike simple carbohydrates (found in sugary snacks and drinks), which create energy highs and lows throughout the day. These peaks and troughs decrease feelings of happiness and negatively affect our psychological well-being.
Antioxidants in brightly coloured fruit and vegetables scavenge free radicals, eliminate oxidative stress and decrease inflammation in the brain. This in turn increases the feelgood chemicals in the brain that elevate our mood.
Omega 3 found in oily fish and B vitamins found in some vegetables increase the production of the brain's happiness chemicals and have been known to protect against both dementia and depression.
Pro and prebiotics found in yoghurt, cheese and fermented products boost the millions of bacteria living in our gut. These bacteria produce chemical messengers from the gut to the brain that influence our emotions and reactions to stressful situations.
Research suggests pro- and prebiotics could work on the same neurological pathways that antidepressants do, thereby decreasing depressed and anxious states and elevating happy emotions.
What happens when you switch to a healthy diet?
An Australian research team recently undertook the first randomised control trial studying 56 individuals with depression.
Over a 12-week period, 31 participants were given nutritional consulting sessions and asked to change from their unhealthy diets to a healthy diet. The other 25 attended social support sessions and continued their usual eating patterns.
The participants continued their existing antidepressant and talking therapies during the trial.
At the end of the trial, the depressive symptoms of the group that maintained a healthier diet significantly improved. Some 32 per cent of participants had scores so low they no longer met the criteria for depression, compared with 8 per cent of the control group.
The trial was replicated by another research team, which found similar results, and supported by a recent review of all studies on dietary patterns and depression. The review found that across 41 studies, people who stuck to a healthy diet had a 24 -35 per cent lower risk of depressive symptoms than those who ate more unhealthy foods.
These findings suggest improving your diet could be a cost-effective complementary treatment for depression and could reduce your risk of developing a mental illness.
• Megan Lee is an academic tutor and lecturer at Southern Cross University.
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call 111.
If you need to talk to someone, the following free helplines operate 24/7:
DEPRESSION HELPLINE: 0800 111 757
LIFELINE: 0800 543 354
NEED TO TALK? Call or text 1737
SAMARITANS: 0800 726 666
YOUTHLINE: 0800 376 633 or text 234
There are lots of places to get support. For others, click here.
- The Conversation
