KEY POINTS:
Mum was right - eating your greens is good for you. But so are your yellows, reds, browns and blues.
In the fight against cancer, fruits and vegetables are the first line of defence.
Lynn Ferguson, head of the Auckland University Centre for Mutagen Testing (mutagens are anti-cancer-causing
properties), has devoted her career to studying the protective effects of diet against cancer.
The centre, part of the Auckland Cancer Society Research Centre, was set up in 1988, but Professor Ferguson has been working with the Auckland Cancer Society since 1979.
She was invited to join by the former director the late Dr Bruce Cain.
"I was given a completely different brief. Everyone else was developing cancer drugs, I was taken in to look at [the] causes of cancer - to look at why New Zealand's got one of the highest rates of cancer in the world.
"We recognise that, okay, you can develop anti-cancer drugs, and that's great, but if you can stop people from getting cancer, that's the best of all. To do that, you've got to understand what's causing it."
And a good deal is already known about its causes. Tobacco smoke, excessive sun exposure and being obese all have strong links to cancer. But diet remains a major factor, accounting for up to a third of all cancers.
Professor Ferguson said people are simply not being as good with fruits and vegetables as they should be. While the recommendation is for five servings a day, the average New Zealander gets two to three.
And the statistics reflect that. Besides having one of the highest bowel cancer rates in the developed world, New Zealand also ranks in the top three countries for breast and prostate cancer prevalence. All three are linked to diet.
"What it means is that the New Zealand diet that we like to think of as healthy is possibly not as healthy as we would like to have it be."
Much of Professor Ferguson's research has focused on the cancer-protecting natural compounds of foods.
Kiwifruit, broccoli, green leafy vegetables and kumara, particularly the purple variety, are all foods she cites as being quite beneficial. Oily fish such as salmon and sardines are also useful.
But certain nutrients are simply lacking in the average New Zealand diet.
"You can have an incredibly healthy diet otherwise and still not get enough selenium."
Preliminary evidence from a major study being conducted by Professor Ferguson suggests that half the Auckland population is "somewhat" deficient in the mineral.
"Not enough to cause a chronic deficiency, but sufficient to increase the risk."
New Zealand soils are deficient in the mineral, so its crops reflect that. But just four brazil nuts a day is enough to meet most people's needs, said Professor Ferguson. Australian wheat is also a good source.
But there remains no cancer-preventing miracle food.
"People want a magic bullet, and I say something like 'broccoli is beneficial', but that doesn't mean you should eat a bucketload. It does mean two or three meals a week which include broccoli is probably a good idea."
