• We can boost our memory, concentration and mental performance by eating the right foods: nootropic foods. (Photographer's Choice/Getty Images)
Trying to keep up with what constitutes a "healthy" diet can be exhausting, but the quality of your diet also plays a critical role in our cognitive function.
By
Margaret Morris, Michael Kendig

Source:
The Conversation
18 Jun 2019 - 10:54 AM  UPDATED 18 Jun 2019 - 11:21 AM

With unending options at the supermarket, and diet advice coming from all directions, filling your shopping trolley with the right things can seem an overwhelming task.

For a long time, we've known diet is key to maintaining physical health.

But emerging evidence indicates diet quality also plays a critical role in our cognitive function.

We're learning some of the best things to eat in this regard include vegetables, nuts and berries, foods containing "good fats" and, possibly, fermented foods.

As well as potentially improving our brain function, eating these sorts of foods could improve our mental well-being – and could even help the planet, too.

KEEPING YOU STRONG
Brain food: what you should be eating for good mental health
You are what you eat, or so the saying goes. Research is now proving the link between what we eat and our mental health is stronger than previously thought.

Diet and brain function

In the face of rising obesity rates, over the past couple of decades, researchers have questioned whether increased weight or poor diet, could influence cognition. They have since looked at what sorts of diets might impair or improve the function of our brains.

Research has also shown short-term memory is poorer in people who report eating more saturated fat and sugar.

Long term follow-up studies show obesity is associated with mild impairments in several domains of cognitive function, including short-term memory, attention and decision-making.

Research has also shown short-term memory is poorer in people who report eating more saturated fat and sugar.

Conversely, the Mediterranean diet has been associated with better brain health and maintenance of cognitive abilities into older age. A Mediterranean diet is based on vegetables, whole grains, legumes and nuts, with healthy fats such as olive oil. Intake of red meat, saturated fats and sugar is limited.

A healthy diet has many elements, so let's look at what particular foods might explain these benefits.

Vegetables, nuts and berries

Evidence indicates eating more vegetables slows the gradual decline in cognitive abilities that occurs naturally as we age.

While all veggies are likely to contribute, those in the cruciferous (Brassicaceae) family may confer particular benefits through their high fibre, folate, potassium and vitamin content. Vegetables in this family include broccoli, cauliflower, brussels sprouts, and fad favourites kale and rocket.

Interestingly, while there's good evidence for the protective role of vegetables, there's less evidence when it comes to fruit.

Berries, though, contain high levels of antioxidants. These compounds protect the body by scavenging harmful free radicals and reducing inflammation. Together these functions are likely to protect our cognitive ability.

Studies in rats, and in older people with mild cognitive impairment, indicate supplementing diets with berries improves performance in various memory tasks.

Nuts, meanwhile, are excellent sources of monounsaturated and polyunsaturated fats, minerals and vitamins. Studies in animals have shown the addition of nuts improves learning and memory. Emerging evidence in humans suggests consuming nuts within a Mediterranean-style diet improves measures of cognition, such as the capacity for verbal reasoning.

THE GOOD STUFF
What are the 7 best nutrients for mental health
While sugary, fatty and processed foods are linked to depression, ingredients rich in vitamins, antioxidants and omegas have the opposite effect. Here are the best foods to boost your brain health.

Healthy fats

Healthy diets such as the Mediterranean diet are also characterised by foods such as oily fish, avocados, olive oil and small amounts of animal-derived fats (such as from red meat).

One of our experiments in rats showed diets high in saturated fat from lard or high in sugar led to memory impairments, whereas an oil-based diet high in polyunsaturated fats didn't.

Importantly, rats fed these different diets did not differ in their total energy intake – only the type of fat and sugar varied.

While we can't comment directly on the effects in humans, these findings suggest eating excess sugar, or animal-based fats may negatively impact cognition.

This is why some kids might not make friends with salad.

Fermented foods

For thousands of years, humans have prolonged the life of foods through fermentation, which increases the proportion of Lactobacillus and other healthy gut bacteria.

Kombucha and kefir are trendy right now, but other popular fermented foods include kimchi, miso, yoghurt and sauerkraut. Intake of these foods is thought to maintain the diversity of the gut microbiome.

GUT HEALTH
Barramundi steamed with Thai spices

This fragrant seafood dish pairs barramundi with pok choy, an excellent probiotic that promotes a healthy microbiome.

Interest in the potential cognitive effects of fermented foods stems from emerging evidence for the importance of the gut microbiota in cognition and health.

It's well known that a poor diet can reduce the diversity of the gut microbiome. Our work in rats has shown the cognitive impairments produced by exposure to an unhealthy "cafeteria" diet – a Western-style diet high in saturated fat and sugar – are linked to changes in the gut microbiome.

Beyond cognition

It's not possible to attribute "miracle" properties to one food group alone. We suggest a balanced, varied diet is the best approach to sustain not only brain health but heart health too.

It's not possible to attribute "miracle" properties to one food group alone. We suggest a balanced, varied diet is the best approach to sustain not only brain health, but heart health too.

And there may be other reasons to seek out these foods. A newly published study showed eating fruit and vegetables improved mental well-being. Subjects tended to feel happier, less worried and reported higher levels of overall life satisfaction.

The link between diet quality and better mental health is now well-established.

Coconut amaranth & millet bowl with warm berries

The recently published EAT-Lancet report adds a further compelling reason to eat healthily: the environment. This commission argued for a "planetary health" diet – akin to the Mediterranean diet – consisting of whole grains, vegetables, fruits, nuts and dairy, healthy fats, with low animal protein and few processed foods.

HOW TO EAT HEALTHIER
Six recipes that make it easy to eat more greens
Looking to bump up your green veg count? Healthy isn't boring with these ideas from Justine Schofield.

It is thought that shifting to such a diet, together with reducing food waste and adopting more sustainable food production systems, will minimise environmental damage and safeguard individual health.

The central message is the health of individuals and of the planet are inextricably linked, and this requires a rethink of global food systems.

 is a Professor of Pharmacology and the Head of Pharmacology at UNSW.  is a Postdoctoral Research Fellow at UNSW. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Watch Mastermind weeknights at 6pm on SBS Australia. All episodes are available to stream at SBS On Demand after broadcast.

GET YOUR BRAIN INTO GEAR
7 ways to eat to boost your brainpower, without taking supplements
Naturally enhance cognition, learning and memory with nootropic foods. Here's what they are.
Here's why guzzling lots of milk can make your baby smart
Your baby's milk-based diet, right up until age two, is vital for their brainpower and cognitive development.
DIY ferments harness the good bugs to boost body and brain
Fermented foods are enjoying a resurgence - Holly Davis explains why that's a good thing for us all.
Happy news: Your brain really does want you to eat more fruit and veg
A world-first trial showed depression is reduced after just three months following a diet rich in vegetables, fruits, wholegrains, legumes, fish, lean red meats, olive oil and nuts.
How too much sugar and saturated fat could be harming your brain
Can eating too much fat and sugar - or just eating too much - affect our memory?
Mellow yellow? The mood and brain benefits of curcumin from turmeric
Another reason to eat curry? There is evidence from both human population and animal studies that a compound found in tumeric may help prevent age-related cognitive decline.