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Out of the blue

Can blueberries save us from age-related brain deterioration?

Question: I've heard that blueberries are good for our brains as we age. But, then again, many things are meant to be the elixir of life. Is there any truth to the blueberry story? (B Smith, Kerikeri)

Answer:

Mental well-being is an important part of ageing successfully, but as we age there's a decline in brain functions, including short-term memory, information retrieval, balance and co-ordination.

According to a 2005 study, reported in Neurobiology of Aging, considerable evidence suggests that "oxidative stress" and inflammation play important roles in brain ageing. Oxidative stress is the cellular damage caused by free radicals that escape our antioxidant defence systems. The human brain is particularly susceptible to such damage, because although it makes up just two percent of our body mass, the brain uses a whopping 20 percent of our total oxygen consumption.

Pumping up the brain's antioxidant defence systems may prevent a decline in brain function. Recent research has discovered that aside from the well-known antioxidants (like vitamins A, C and E), there are thousands of other compounds in fruits, vegetables, whole grains, seeds and nuts with antioxidant action.

Blueberries have been attracting attention because they appear to have greater antioxidant activity than other fruits. The key is the anthocyanins that give them their colour.

A 2007 review of research, published in Molecular Nutrition & Food Research, reported that age-related brain decline was reduced and even reversed in animals fed diets high in blueberries. Although the research is promising, it was only trialled with animals, so we can't conclude that eating lots of blueberries will save humans from declining brain function. But it does help to explain why eating diets high in fruit, vege?tables and wholegrains improves our well-being.

So, aim to meet the 5+ a day target for fresh fruit and vegetables and remember that the greater the variety, the greater the chance we'll get all the different colour compounds that enhance our antioxidant defence systems.

Question: Kitchen sponges can harbour a lot of bacteria. What is the best way to get rid of it? (J Campbell, Invercargill)

Answer:

As warmer summer weather allows bacteria to multiply more rapidly, it's a good time to think about avoiding food-borne illnesses. Let's face it, nobody wants to hear that family or friends have fallen ill with a stomach bug the day after they dine at your home!

Kitchen sponges or cloths are among the key culprits in spreading bacteria around the kitchen. The average kitchen sponge contains tens or hundreds of thousands of bacteria, yet research shows that most of us replace kitchen sponges only once a month.

A recent study by the US Agricultural Research Service into five different methods of treating dirty, bacterial-laden sponges found that soaking them in either 10 percent chlorine bleach solution, lemon juice or deionised water killed between 37 and 87 percent of bacteria.

The researchers found that after putting the sponges through a full dishwasher cycle or giving them a burst in the microwave, less than one percent of yeasts and moulds survived.

The recommendation is to microwave damp sponges or cloths for one minute or put them into the dishwasher for a full cycle that includes a drying phase. It's also a good habit to sterilise sponges and cloths every other day.

Email: nutrition@listener.co.nz, or write to: "Nutrition", c/o Listener, PO Box 90 783, Auckland.