Blueberries, red cabbage and red onions could help reduce your chance of getting dementia.
More than 62,000 New Zealanders had dementia last year and that was expected to increase to more than 170,000 by 2050, according to Alzheimer's New Zealand.
But there are many things you can do early in life to reduce the risk of developing dementia.
To mark World Alzheimer's Day tomorrow, we look at what you can do to keep your brain healthy.
"The brain is linked to the gut so what we eat is really important," Kiwi health expert and integrated medical practitioner Dr Frances Pitsilis said.
Purple fruit and vegetables such as blueberries, red cabbage and red onions were particularly good antioxidants - perfect for preventing the oxidative damage to the brain which was common in people with Alzheimer's disease.
Turmeric also appeared to be helpful in preventing dementia because the curcumin in it helped prevent the spread of plaque found in the brain of Alzheimer's patients, she said.
Pitsilis said it was important people ate fruit and vegetables that covered "all the colours of the rainbow" to make sure they were getting all the vitamins and minerals they needed to keep their body healthy.
She encouraged her patients to always have frozen mixed vegetables on hand as a back-up. Because they were snap frozen they could be better for you than fresh vegetables that had been sitting in the fridge for a couple of weeks, she said.
Exercise was also essential and was one of the most powerful preventatives of Alzheimer's, she said.
She said 75 per cent aerobic and 25 per cent resistance was best for prevention.
Alzheimer's New Zealand has been holding Memory Walks around the country this month to mark the occasion and to remind people of the importance of exercise as a preventative.
"What is good for the heart is good for the brain," the organisation said. That included topics like food, exercise, drinking and smoking.
Pitsilis said they key was to look at your own family history and to start taking preventative measures seriously early in life.
As well as looking at family history, a test could now be done to tell you if you had the APOE gene which has been linked to the disease, she said.
If you had one of those genes the chance of developing a form of dementia increased 40 per cent and if you had two APOE genes that chance jumped up to 70 per cent.
The test in Auckland cost $240 but Pitsilis said she believed it was worth it because "knowing is power".
Those who had the APOE gene needed to take prevention even more seriously and should avoid eating animal fats, gluten, drinking and smoking. A vegetarian, Mediterranean type diet was best, she said.
Alzheimer's New Zealand agreed there was good evidence that eating a Mediterranean-style diet could reduce the risk of developing some forms of dementia.