We often hear about the wonders of exercise and mindfulness, and how greatly they can serve the one in three Australian women who will suffer from anxiety over their lifetime. But, as we crunch and meditate and jog, what few consider is how diet influences mental health.
According to Professor Felice Jacka, president of the International Society for Nutritional Psychiatry Research, that’s a mistake.
“There is very extensive evidence that there is a link between the quality of people’s diets and their clinical depressive and anxiety disorders,” she says.
Keep calm and eat blueberries.
Through her work as director of Deakin University’s Food and Mood Research Centre, Professor Jacka has discovered that “if you manipulate diet, it has a very direct impact on the brain”.
In fact, the size of the hippocampus – a complex brain structure responsible for memory and learning – can be modified with dietary changes in animals. Indeed, she says, “diet will modify the brain, the information in the brain and brain plasticity, very quickly”.
While some risk factors for anxiety are immutable – for instance, one cannot readily change their socioeconomic status, their family history, or previous life trauma – diet is something you can optimise today.
Here’s where to start.
Do: eat more fibrous foods
Examples: fruits and vegetables, wholegrain cereals (like whole rolled oats, barley, rye, brown rice), legumes (beans, lentils, chickpeas), nuts, and seeds.
Fibrous foods are brilliant because they are difficult to digest, meaning they are broken down by fermentation in the large bowel. During this process, they release short-chain fatty acids, which have been found to “reduce the [body’s] stress response” in animal experiments.
If you’ve been suspicious about popular culture’s obsession with gut health, don’t be. According to Professor Jacka, research into the gut-brain axis is “transforming medical research and our understanding of medicine”.
“The gut microbiome, we now understand, is very important to virtually every aspect of our physical, mental, and brain health."
“We think the gut microbiome is very important for people with anxiety. The good thing is you can change your microbiome within a very short space of time, within days, probably even within hours, given how quickly the bacteria multiply.” Despite 50 per cent of all mental disorders presenting before the age of 14, less than half a per cent of Australian children are eating enough fibre, leaving them susceptible to poor gut microbiota and, eventually, diminished brain health.
Do: incorporate healthy fats
Examples: olive oil and fish oil.
According to Melbourne dietitian Melanie McGrice, people with anxiety should look to eat more fish to reap the benefits of Omega 3s, which have been found to decrease symptoms of depression and anxiety.
“I’d also recommend eating the fish itself, not a fish oil tablet,” McGrice said. “Fish oil supplements have been found not to have the same effect on disease and anxiety, so I think people need to be focusing on eating the fish itself.”
Do: reach for polyphenols
Examples: berries, green tea, dark chocolate, red wine, soy, brightly coloured fruits and vegetables.
Professor Jacka says polyphenols – that is, the compounds found in natural plant-based foods – “seem to have a very beneficial impact on the gut” and therefore the brain.
McGrice agrees, adding polyphenols' anti-inflammatory properties are wonderful for anyone with a predisposition to anxiety disorders.
“From an anecdotal perspective as a clinical dietitian, once we’ve encouraged someone to move to an anti-inflammatory diet, they’ve reported reduced anxiety and better mood overall,” she said.
Do: enjoy fermented products
Examples: kefir, yogurt, kombucha, tempeh, sauerkraut, and fermented vegetables.
While Professor Jacka’s research into fermented foods and their impact on anxiety is in its infancy, she believes they will be found to be “very beneficial” to the gut-brain axis.
Yep: all that kombucha you see on Instagram might just live up to the hype.
“Fermented foods don’t necessarily have a whole lot of live bacteria in them, but what they do have is short-chain fatty acids,” Professor Jacka said. "We think fermented foods are very important for our health… we would suggest that people who have anxiety should be including fermented foods in their diet every day.”
Don’t: drink too much caffeine or alcohol
Because it is a stimulant that will evoke jittery effects in the body, McGrice advises anyone with anxiety to “be careful about how much coffee they drink per day”.
"One a day is enough."
The same goes for alcohol – a sedative and depressant – that has a detrimental impact on the central nervous system in the hours after consumption.
“I usually recommend that younger women should really be limiting their alcohol intake altogether, particularly those with anxiety disorders."
Don’t: be too hard on yourself
While ultra-processed foods and trans fats “will have a negative impact on the hippocampus”, Professor Jacka said anyone with anxiety should remember there is no "one size fits all" answer to diet.
“People who are highly anxious often have real health anxiety, and so they pay very particular care to their health and diet to the point it can become a nasty psychiatric disorder in itself, orthorexia,” Professor Jacka said.
“You can have too much of a focus and too much worry related to diet and exercise to the point it becomes unhealthy.”
McGrice adds that perfection isn’t necessary: people with anxiety should simply look to have diversity in what they eat, and opt for fibrous foods wherever they can.
“It’s not just the food alone, it’s the way the food is eaten: the social aspects, the smell, the people. Take the time to enjoy your food.”
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