We hear a lot about childhood obesity but another trend that has health authorities jittery is the spreading waistlines of the over-50s. An increased risk of heart disease is not the only problem associated with ageing and weight gain; there can also be effects on the brain.
''By itself, ageing is a risk factor for cognitive decline but obesity is another, and around 70 per cent of 55- to 74-year-olds are overweight or obese,'' says Jon Buckley, the director of the Nutritional Physiology Research Centre at the University of South Australia. ''We now have both factors working together to increase problems with brain function.''
But Buckley says ageing brains may have a new ally: foods based on beans and lentils, including burritos, minestrone and dahl.
A preliminary study from the University of Manitoba in Canada found that eating a serve of legumes every day for eight weeks can improve the function of blood vessels, making them smoother and less rigid. Building on that evidence, Buckley is working on new research to see if eating legumes daily benefits the blood vessels supplying the brain.
Healthy blood vessels are more resistant to vascular dementia (the most common form of dementia after Alzheimer's) as well as heart disease and stroke.
''Supple arteries cope much better with the pressure of blood pumping around our body every day because they can expand to accommodate the volume,'' he says. ''But if they're like steel pipes they don't cope well and blood pressure increases.''
Legumes are already linked to healthier cholesterol levels because of their high fibre content. They may also have positive effects on arteries, thanks to their various bioactive compounds - and to the fact that they might displace other less healthy foods from the plate.
The real challenge is getting us to eat more of them. Only 22 per cent of Australians eat legumes once a week, according to a study by the Grains & Legumes Nutrition Council. One of the main reasons for this is that many people do not know how to cook them.
Legumes are quiet achievers. They sustain poorer people all over the planet, but in meat-loving Australia, their status is as also-rans. It doesn't help their image that they're known as meat substitutes, yet they're not pretend meat. With their earthy flavours, legumes are in a class of their own and are a versatile base for creating curries, casseroles, soups and salads - if only we knew how.
The big hurdle for lots of us is the idea of pre-soaking beans before cooking, but you can skip this step by using canned legumes. Once you're an old hand you can work on soaking and cooking beans in bulk and storing them in the freezer, but in the meantime, chickpeas, red kidney beans and cannellini beans are on every supermarket shelf. You'll find canned black beans and borlotti beans at delis or larger greengrocers. Lentils don't need pre-soaking. As for cooking, once you get started you realise that making a pasta sauce or curry with beans or lentils is much the same as cooking with minced or chopped meat. Start by cooking some onions and then toss in your legumes and flavours. Easy.
A dish that includes legumes need not be meat-free. You can just use less meat and pump up the volume with legumes. Good combinations are chicken with chickpeas, and beef with black beans, red kidney beans, or borlotti beans.
Legumes make it easy to increase your vegetable intake. ''A serve of meat gives you protein, but a serve of legumes gives you two for one; protein and vegetable, both at the same time,'' Buckley says.
Paula Goodyer blogs at smh.com.au/chewonthis