Hi, I thought you may like this Mentalrobics exercise from Braingle.com:
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Saturated / Unsaturated Fats

Most people know that the saturated and trans fats that are found in meats and processed foods are bad for their heart, but you may not know that they are also bad for your brain too! Unsaturated fats like those found in fish, nuts and most vegetable oils can actually improve your cognition. A recent study found that people who ate large quantities of saturated and trans fats had an increased risk of getting Alzheimer's disease [ For more on 'Alzheimer's disease' go here: http://www.braingle.com/mind/361.html ]. In the study, those people who ate the more unsaturated fats had a decreased risk of getting the disease.

In particular, eating fish has been showing to decrease Alzheimer's risk and protect other memory functions. This may be because fish are high in omega-3 fatty acids, which have been shown to have beneficial effects on health.
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For more mind exercises: http://www.braingle.com/mind/