THE NEW BRAIN BOOSTING DIET
As science discovers that a diet clinically proven to control high blood pressure could also future-proof your mental health, wh asks...
Your attention was probably elsewhere in the late ’90s. Watching the Wannabe music video on repeat to decide which Spice Girl you were, or trying to work out if Leo and Kate could both have fitted on that floating door. Either way, you may have been too preoccupied to spot a study published in The New England Journal of Medicine in 1997 about how a specific way of eating can significantly influence blood pressure. The dietary approaches to stop hypertension (DASH, to its mates) diet was found to substantially reduce hypertension (hence the name), thanks to the reduced fat consumption that came with an approach rich in whole grains, fruit, veg and low-fat dairy. Cool story for anyone looking to reduce their blood pressure stats. But also relevant for pretty much everyone else, because – so says a growing body of research – this niche ’90s diet could be the key to futureproofing your mind. Bet we’ve got your attention now.
So why all the buzz? In April
2018, more than two decades after DASH was first conceived, a study presented to the American Academy of Neurology found that those who followed the approach, or something similar, were less likely to develop depression than those who didn’t. Conversely, those same researchers from Rush University Medical Center in Chicago found that the more closely participants followed a typical Western diet (high in saturated fat and red meat, low in fruit and vegies), the more likely they were to develop depression. “This is a relatively small study that was observational in nature, so we can’t claim a causeand-effect relationship,” says Dr Laurel Cherian, assistant professor in the Department of Neurological Sciences at Rush and lead author of the study. “I think the results are one more piece in a larger puzzle that is coming together to show us that diet is a valuable weapon in our arsenal against depression.”
Eating your feelings
Cherian’s not wrong. Other major pieces of the puzzle include a 2017 study in which scientists from
Spain’s University of Navarra found that people who followed the DASH diet, even moderately, had a lower risk of developing depression. A Deakin University team also found that a diet centred on fruit, vegetables, fish and whole grains – DASH, essentially – was associated with lower odds of developing major depression and anxiety disorders, while a Western diet was linked with higher odds. Particularly significant was the fact that this research didn’t just focus on older people (as in the Rush study) but included women as young as 20.
Sure, the notion that what you eat affects your mental health isn’t new. But while you might have long suspected that this relationship exists, it’s only relatively recently that experts have begun working out why it does. However – as with Melania and Donald – understanding the connection is tricky. “Proving a direct causal relationship between health and food is enormously complicated because there are so many variables that can affect outcomes,” says Kimberley Wilson, whose practice, Monumental
Health, combines the latest research into nutrition neuroscience with psychological therapy. “Add mental health into the mix and you’re introducing another layer of
complexity given that, historically, mental health research hasn’t had the same funding as, say, heart disease or cancer.” But, she explains, there are two key strands that researchers are exploring: the ways in which following a good diet can help safeguard your mental health, and how and why a bad diet can negatively affect your mind.
What’s really fascinating? Recent research indicates it’s what you
don’t eat on the DASH diet that could be key to understanding this protective effect. It can be explained in a word that’s captured the imagination of the scientific community the way inflatable pool toys have captured that of Instagrammers: inflammation. In the past decade, experts have started looking into the potential links between inflammation and depression – specifically, the idea that reducing the former could protect against the latter.
In a 2016 study published in Current Neuropharmacology, researchers concluded that a better understanding of inflammation in the brain could help treat depression more effectively. This is something Professor Edward Bullmore, head of psychiatry at Cambridge University, investigates in his book The Inflamed Mind – the growing body of evidence that links eating high-fat foods with inflammation, which, in turn, can contribute to depression. “There are many inflammatory cells embedded in fatty adipose tissue, which is why obesity is associated with an increase in blood levels of inflammatory proteins, such as cytokines,” he explains. Cytokines are proteins that play a vital role in the way our cells talk to each other. “The evidence shows that increased cytokine levels can cause inflammation in the brain, leading to withdrawal from social contact, loss of pleasure and other depressive symptoms,” he adds.
The fact that an association has been found between obesity and inflammation, Bullmore says, could help to explain why there is also a link between obesity and depression. But as to the question of whether an anti-inflammatory diet can protect against depression, he is clear: we need a great deal more evidence before we can make any conclusions. “I think it’s conceivable, based on my work, that changing your diet could have an anti-inflammatory effect – and therefore could offer mental health benefits – but we need much more data to be sure,” he says. .
The absence of high-fat foods only goes some way towards explaining why DASH could be so powerful. Factor in the protective effect of many of the foods on its menu and the case for keeping your mind healthy via your plate stacks up. This is where the mind-gut connection comes in. Prebiotic plants – the likes of asparagus, leeks and Jerusalem artichokes – feed your gut microbiome as effectively as a Mcmuffin feeds a hangover. “Prebiotics are dietary fibres found in plants that the good bacteria in your gut feed on
to multiply,” explains psychiatry professor Dr Philip Burnet. “Gut bacteria contain an amino acid that affects a certain type of molecule in the brain. I wanted to see if increasing beneficial gut bacteria with a prebiotic supplement – and in turn producing more of this amino acid – could improve mood and cognitive processing. It turns out it does in animals, and to some extent in humans, but this isn’t happening via the amino acid that we thought. We now think it happens via the immune system, and the molecules produced from the bacterial digestion of the prebiotic.” Once again, more human studies are needed, but Burnet believes prebiotic supplements could work via the same mechanism as antidepressants, by reducing levels of stress hormones in the brain.
So what about prebiotic plants – the kind you’ll find on your average DASH plate? “Plants contain carbohydrates, which have prebiotic properties, meaning they should provide the same health benefits via the gut bacteria,” adds Burnet. “But all natural prebiotics and supplement formations still need to go through clinical trials to test if they really do have therapeutic effects on mental illnesses. So far, we have only shown that a prebiotic supplement influenced one psychological pathway that underlies mood – we didn’t see a change in mood per se, and we won’t know more until more work is done.” Still, no harm in chucking some leeks in that salad.
If you’re feeling the urge to take up a fresh-veg box subscription right now, consider the bigger implications for people experiencing an ongoing mental health battle. We need to consider the evidence in context, adds Cherian. “When we talk about the role that diet plays in mental health, it isn’t a case of telling people [a strict formula] because it certainly isn’t that simple,” she says. “But changing your diet in a way that reduces your consumption of high-fat food and increases your intake of prebiotic plants could play a crucial part of a comprehensive plan for preventing, and also treating, depression – comprehensive being the important word.” Cherian emphasises medication, therapy and exercise all play key roles and people who combine them with good nutrition may see the greatest benefit to their mental health.
Where this diet has real promise is that there’s no number-counting or a forever-off-limits list of foods. “DASH encourages people to eat well without limiting what they allow themselves,” Wilson explains. “Like the Mediterranean way of eating, DASH is neither restrictive nor prescriptive. Because it provides guidelines for people to work within and adjust to suit their lifestyle, there’s no falling off the wagon.”
In short, it’s a diet in the truest sense of the word. One that actually recognises you’re human. Now, that’s what we call seriously smart.