Veging out ... school kids snack on fruit and veg as part of the healthy eating Sip and Crunch : Ken RobertsonSwap chips for carrot sticks and lower your blood pressure. Paula Goodyer reports.
The trouble with food processing is that what starts off as good food, packed with all the right stuff, often ends up with fewer nutrients and added extras that can compromise your health. Peel the leaves and silk from a cob of corn and you've got a sweet, juicy package of fibre and potassium. But turn it into a bowl of cornflakes, and it's lost most of its potassium and gained sodium. Why does this matter? Because potassium has the power to keep blood pressure down, and sodium has a habit of pushing it up, explains Dr Caryl Nowson, professor of nutrition and ageing at Deakin University's Centre for Physical Activity and Nutrition Research.
What's good about potassium is that it helps to keep artery walls nice and relaxed, making it easier for blood to flow through them, she explains. But too much sodium does the opposite: it tightens the artery walls, making it harder for blood to get through. The result: your heart has to pump harder - and up goes the blood pressure. No big deal? Wrong. High-blood pressure raises your risk of heart disease and stroke and, says the World Health Organisation, is the third leading cause of death and disability after malnutrition and unsafe sex.
Studies of societies that didn't depend on processed food - such as Papua New Guinea Highlanders - found that high-blood pressure was almost unknown. It's partly because they ate much more potassium than sodium, thanks to a diet of natural food - just the way it's meant to be, says Nowson. But a typical Western diet, high in processed food - the source of most of the sodium that we eat - gives us the reverse: levels of sodium that are higher than potassium.
So while we need to eat less salt, less processed food and go easy on the fish sauce, we also need more vegetables and fruit to pump up the potassium in our diets. Replacing refined cereals with whole grains counts too, Nowson adds - when whole grains are refined to create lightweight bread and breakfast cereal, out goes the potassium along with the fibre.
But while two serves of fruit is easy to manage, eating at least five serves of vegetables daily can be challenging for some people - especially if they wait until dinner to try to fit them all in. One solution, says Nowson, is to snack on raw veg with hummus or other healthy dips on the side, instead of breaking out the biscuits.
"Snacking on vegetables is still considered weird - we need a shift in thinking to make snacking on them more acceptable," she says.
After all, it's not just their potassium content that makes vegetables and fruit so kind - but the fact that eating more of them means less room for sodium-loaded processed food.