In a column last month I explored the link between dementia and homocysteine, and suggested higher intakes of certain nutrients may lower the levels of this blood constituent and help keep our wits about us as we age. October also saw the publication of a study in the Archives of Neurology which linked eating fish with a significantly reduced rate of brain-function decline. This research comes on the back of a wave of other studies concluding that the consumption of fish appears to help keep dementia and impaired brain function at bay.
Research linking fish-eating to preservation of our mental faculties has led scientists to look for the component in fish that's good for the brain. Researchers have focused on the omega-3 fats - found most abundantly in 'oily' fish such as salmon, mackerel, herring and sardine - for an explanation. These come in two main forms: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). While DHA is important for brain development and structure, EPA seems to have a more important influence on the running of the brain.
The fundamental roles these fats appear to play in brain function mean they have the potential to combat not only dementia, but mental illness, too. Studies show individuals with low levels of omega-3 fats in their bloodstreams generally have an increased risk of depression and schizophrenia. This finding has prompted researchers to assess the effect of supplementing omega-3 fats in people suffering from depression or schizophrenia.
Partly because of its role in the smooth running of the brain, EPA has been the focus of the bulk of such research. In most of these studies, EPA has been given in addition to conventional medicine. Happily, the majority of this research has shown that EPA has the ability to bring significant reductions in depressive and schizophrenic symptoms. The evidence is strong enough, I think, for the supplementation of EPA to be considered in those suffering from depression or schizophrenia, though I recommend this be done under medical supervision.
The required dose of EPA needed to bring benefits in mental disorder is in the region of 1,000- 2,000mg (1-2g) per day. Although eating oily fish a couple of times a week will have a positive effect, supplementation with EPA provides a practical way to get assured amounts into the body on a regular basis. The apparent potential omega-3 fat has to promote normal mental function gives credence to the opinion fish is the ultimate brain food.
Dear John
In the past, you have been sceptical about the supposed benefits of cholesterol reduction. Have you changed your mind in light of the recent study in The Lancet?
BC
Cholesterol reduction is believed to reduce the risk of heart attacks and strokes. Previous evidence suggests that using cholesterol-reducing drugs - 'statins' - in individuals who have already had a heart attack or stroke ('secondary prevention') reduces the risk of further problems.
My scepticism comes from evidence that suggests that the use of these drugs in individuals with no history of heart attack or stroke ('primary prevention') does not reduce the risk of death. The recent Lancet study analysed 14 trials - a mix of primary and secondary prevention approaches - and concluded that statin therapy helps to save lives. But unless the primary prevention data is analysed on its own, it's impossible to say whether this latest study supports use of statins in healthy subjects. Until such evidence becomes available, I remain sceptical about the use of statin drugs in all but those deemed at high risk of heart attack or stroke.
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Nutrition news
Each human sperm carries genes in the form of DNA. In some cases, sperm DNA can be damaged or 'fragmented' - a cause of male infertility. It has been suggested that DNA fragmentation may be the result of what is known as 'oxidative stress' - essentially, damage related to free radicals. It has been suggested that DNA fragmentation might be combated by substances known as antioxidants, that have the ability to quench free radical activity.
In a study published recently in the Journal of Andrology, researchers in Italy tested the effects of two antioxidants (vitamins C and E), or placebo in a group of men with abnormally high levels of DNA fragmentation in their sperm. Each of these two nutrients was given at a dose of 1g a day for two months. Treatment with placebo was not found to lead to any reduction in levels of sperm DNA fragmentation. However, those treated with vitamins C and E saw their levels of DNA fragmentation fall from an average of 22.1 per cent to an average of 9.1 per cent.
This study suggests treatment with antioxidant nutrients over a relatively short period of time may lead to significant reductions in levels of sperm DNA fragmentation.
