A 10-year Australian study into the link between diet and depression has found that junk food isn’t just wrecking our physical health – it’s wrecking our mental health as well.
The Latest Findings
Psychiatric researcher and Associate Professor at Deakin University in Victoria set up a study examining the influence of diet on depression in a large group of Australian women. After taking issues such as education, physical activity, and socio-economic status into account, what she found was extraordinary. Women who ate a processed food diet were 50 percent more likely to have a depressive disorder than those who ate a high-quality whole food one.
The findings generated huge international interest and more massive studies backed her research. A similar study on 3,500 British civil servants, found that those eating high-fat, high-sugar foods were 58 percent more likely to develop depression that their healthy eating counterparts.
While a second study, of 10,000 middle-aged Spanish university graduates, found that a Meditteranean-style diet was hugely beneficial in preventing mental disorders, while a fast-food diet increased depression risk.
“Diet matters to depression,” Professor Jacka says. “Better quality diets are consistently associated with reduced depression, while diets high in processed foods are associated with increased depression and often anxiety. Worryingly, this seems to be the case right from the start of life.”
From Pregnancy to Childhood And Beyond
“We led a very large study of more than 20,000 mothers and their children that showed the children of mothers who ate an unhealthier diet during pregnancy had higher levels of behaviours that are linked to mental disorders”, says Professor Jacka.
“This is consistent with what we see in animal experiments, where unhealthy diets fed to pregnant animals result in many changes to the brain and behaviours in offspring. This is very important to understand if we want to think about preventing mental disorders in the first place.”
There has never been a more important time for her work. In the 20 years betweem 1986 and 2006, data from the US and UK found that the percentage of young people suffering from mental health issues had doubled.
This is particularly depressing since the average age for the onset of anxiety is just six, and for depression it’s 13, and once children develop these conditions, they can become recurrent life-long issues.
So What Should Be On Your Dinner Plate?
Professor Jacka recommends the Mediterranean diet: vegetables, fruit, whole grains, legumes, nuts, olive oil, seafood; poultry, eggs, cheese, yogurt in moderation; red meat and sweets less often.
She says that 30g of nuts daily are beneficial. “Nuts are very high in antioxidants and oxidative stress underpins most non-communicable diseases. Your body needs good nutrition to work properly and so does your brain.”
She also recommends looking after our gut health by increasing fibre in the form of plant foods and including vinegars, such as balsamic and apple cider vinegar, in our diets. In addition, she recommends fermented foods, such as sauerkraut and kombucha, as a good way to introduce friendly bacteria to our intestines.
And what about nutritional supplements? There is evidence that zinc taken in conjunction with antidepressants improves their effectiveness. An amino acid called N-acetyl Cysteine (NAC) has bene shown to help people with depressions and B vitamins may play a role too. Also, fish oil has been found to help prevent at-risk young people from developing full-blown psychosis.
“It could be that in the future, referrals to dietitians will be common for people with mental illness,” Professor Jacka says.