Refined carbs aren't exactly health heroes and are often accused of raising the risk of obesity, heart disease and type 2 diabetes. But if foods like white rice and pasta are so bad how come they're a big part of some of the world's healthiest diets, like traditional Japanese and Mediterranean diets?
It's a question raised in The Mindspan Diet, a new book by Harvard Medical School researcher Dr Preston W. Estep that looks at the eating habits of people who not only live longer but whose brains stay sharper longer. Estep calls them the "Mindspan Elite" – those living in areas noted for their numbers of both long lived people and lower rates of dementia such as parts of Japan and southern France and Italy.
![There's a time for refined foods.](/web/20170112000757im_/http://www.theage.com.au/content/dam/images/g/t/n/o/4/0/image.related.articleLeadwide.620x349.gtn83j.png/1483907137395.jpg)
Their meals might be different but they have things in common, Estep says – less meat and sugar, moderate to high amounts of fish and seafood, more beans and other legumes, more mono-unsaturated fat, abundant plant chemicals like polyphenols and tannins from vegetables fruit, wine, coffee and tea, fermented foods – and plenty of greens including leaves, herbs and seaweed.
While refined carbs get a bad rap, the real problem is swapping a traditional eating style for a western diet with more fast food, says Estep, director of Gerontology at the Harvard Personal Genome Project, who also claims that a high iron intake from too much red meat, iron fortified foods and iron supplements may increase the risk of dementia by creating an iron overload in the brain.
His comments about carbs make sense. There's a difference between a bowl of naked two-minute noodles and a pasta dish with fresh vegetables and a leafy salad on the side – just as there's a difference between packaged breakfast cereal with 25 per cent sugar and a breakfast of toasted white bread with tomatoes, olive oil and garlic.
How we prepare, cook and eat refined carbs like rice and pasta also makes a difference to how rapidly our bodies absorb them, Estep points out. White rice generally has a high GI, meaning it's rapidly digested, resulting in high levels of blood glucose – and too many high GI or "fast" carbs over time can increase the risk of type 2 diabetes. On the other hand, shorter cooking times that leave rice and pasta with a chewier texture slow the rate of digestion as does eating them with fermented foods like vinegar as in pickled olives or salad with vinaigrette dressing.
Traditional carbohydrate foods like pasta, made with eggs, rice and good sourdough bread – even white varieties – are also minimally refined, adds Ngaire Hobbins, a dietitian specialising in ageing and brain health and the author of Eat to Cheat Dementia.
"Although they may have had fibre removed, they haven't undergone a lot of processing that adds preservatives or that involves the repeated heating and cooking needed to produce many commercial baked and snack foods. That's important because one factor that increases the risk of dementia is chronic low level inflammation and the more steps a food undergoes in processing the more likely it is to increase inflammation," she explains.
"Rice and pasta are also a base that you can add good foods to like vegetables, herbs and good oils like extra virgin olive oil."
It's true that basing your diet on too many refined carbs over time can contribute to raised blood glucose levels and increase the risk of type 2 diabetes – and that diabetes in turn raises our dementia risks. But it's an oversimplification to draw a line between refined carbs, diabetes and dementia without considering other factors like physical activity and what else you eat, Hobbins stresses.
"Keeping blood glucose levels healthy isn't just about what we eat but also what our bodies are doing. Physical activity and muscle are important for helping to control blood glucose levels because muscle uses glucose for fuel – but with age we lose muscle if we don't work to maintain it," she says.
The Mindspan Diet by Preston W. Estep is published by Nero, Rrp $29.99