A dietitian's guide to eating your way to a healthier brain

• Adam Liaw's salmon fillets with caramelised onion and wilted greens
• Adam Liaw's roasted broccoli with chilli, garlic and parmesan

As the average life expectancy in Australia has improved over recent decades, so too has our understanding of ageing and the interest in keeping our brains as healthy as possible.

Diet is one variable known to play a key role in brain health, with a growing body of evidence showing specific eating patterns and individual foods are associated with improved brain function as we age, and a reduced risk of degenerative neurological conditions such as Alzheimer's and Parkinson's disease.

So, if one of your goals is to live a long and healthy life, or if you just want to give your brain a boost, here is what the science has shown us so far about the best diet for a healthy brain.

Our dietary choices and our eating patterns influence the brain functionally and operationally via several pathways.

Firstly, key nutrients including omega-3 fats help the brain to form and grow, and then help with the function of signalling centres and transportation of neurotransmitters in the body.

It has been shown that closely following the MIND diet can slow brain aging by as much as seven and a half years.

Nutrient intake affects cognition and memory, and plays a role in age-related deterioration that can occur in the body cells, including brain cells, as a result of chronic inflammation.

While plenty of research focuses on individual nutrients and foods and how they affect our brains, there is strong scientific evidence for one diet in particular that has been shown to help slow the decline in cognitive function.

The MIND diet, or the Mediterranean-DASH Intervention for Neurodegenerative Delay combines the Mediterranean diet, known for its heart and general health-related benefits, with the DASH diet, known to help reduce blood pressure.

Specifically, it has been shown that closely following the MIND diet can slow brain aging by as much as seven and a half years.

What is not yet known is why the MIND diet has such a significant brain-related benefits. One theory is that the diet, which is exceptionally rich in antioxidants and low in pro-inflammatory fats, helps to reduce oxidative stress, which is extremely damaging to the brain.

It is also thought that the diet may help to reduce "beta-amyloid" proteins, which can accumulate and form plaques in the brain. These plaques are one of the primary causes of Alzheimer's disease; they disrupt the communication between cells and result in cell death.

One of the best things about the MIND diet is that it features some very specific recommendations that make it relatively easy to follow.

Leafy greens

Kale, spinach and rocket feature frequently on the MIND plan thanks to their extremely rich nutrient profile of vitamins, minerals and antioxidants. There are nutritional benefits associated with eating leafy greens (raw and cooked). The MIND plan includes at least six serves (½ cup each) of leafy greens in the diet every week.

More brightly coloured vegies

As a general rule of thumb, the brighter the colour the vegetable, the higher the nutrient content – think carrots, zucchini, red capsicum and sweet potato. The MIND plan includes at least one serve of vegies in the diet a day in addition to leafy greens. If you consider that the Mediterranean diet includes seven to 10 serves of fresh fruit and vegies a day, basically the more brightly coloured vegies you consume, the better for your health and your brain.

Wholegrains

The MIND approach suggests at least three serves of wholegrains such as oats, rye, faro or brown rice every day. Wholegrains are rich sources of vitamins B and E, and offer good amounts of dietary fibre, a key component of digestive health. Future research may indeed find a specific link between dietary fibre, gut microbiome and brain health.

Nuts

A handful of nutrient-dense nuts five times a week offers good fats, vitamin E, dietary fibre and protein. A daily serve of nuts has also long been associated with good health and weight control.

Berries

All fruit is good for us but berries stand out for their rich antioxidant content. Regular consumption of blueberries in particular is associated with brain health. The MIND diet suggests berries be eaten at least twice a week.

Legumes

One of the richest dietary sources of soluble fibre, legumes include black beans, kidney beans and chickpeas. They are a protein- and nutrient-rich food we could all do with eating a lot more of. On the MIND plan they are recommended at least three times a week.

Seafood and poultry

The MIND plan has a heavy focus on lean and omega-3 rich proteins including chicken and fish. Chicken is recommended twice a week and fish at least once. To optimise omega-3 intake, include oily fish such as salmon in the diet two to three times a week.

Extra virgin olive oil

Forget vegetable oil or butter, the MIND plan recommends that extra virgin olive oil is the oil of choice both as an added fat and as the primary cooking oil thanks to its rich antioxidant content.

Wine, in moderation

Before you get too excited – yes, wine is included in the MIND plan, but at most a glass per day, not a bottle.

Avoid these altogether

Butter, fried food, sugary snacks and processed foods. Unlike many dietary plans that suggest moderation, the MIND plan has specific recommendations for how much saturated fat, sugar and processed oils are eaten. It is suggested that less than a tablespoon of butter or margarine is used daily; cheese just once a week; red meat no more than three serves each week; and fried foods no more than once a week.

Susie Burrell is an accredited practising dietitian.