Dementia is an issue many of us would rather avoid as we age, and in recent years there has been considerable interest in specific dietary strategies that might help here. Seeing as about 70 per cent of the dry weight of the brain is fat (much of it saturated), I’m inclined to think a diet low in fat (as advocated by our governments and most health professionals) may not the way to go. The brain also contains about a quarter of all the cholesterol in the body, and this substance performs critical functions within the brain. This fact gives me another reason to doubt the wisdom of driving cholesterol levels to ever-lower levels.
One theory about the processes that underlie dementia concerns inflammation. Inflammation is generally a sign that something needs healing within the body. For example, an in-growing toenail can lead to inflammation – the cardinal signs of which are pain, redness and swelling. Inflammation results from the action of white blood cells (immune system cells) and the release of inflammatory substances. Sometimes, though, inflammation is not localised, but generalised throughout the body. This generalised inflammation, sometimes referred to as ‘systemic’ inflammation, is usually long-term (chronic) in nature, and it might pose hazards for the brain.
Inflammation in the lining of the arteries supplying blood to the brain might cause narrowing of these vessels leading to reduced blood supply to the brain (‘hypoperfusion’ of the brain). Also, there is increased risk that small areas of the brain will die (infarcts of the brain) due to lack of oxygen and nutrients. In fact, sometimes dementia is diagnosed as ‘multi-infarct dementia’. Apart from a negative effect on blood vessels, inflammation may be directly toxic to the brain.
Keeping inflammation to a minimum would seem to be good for the brain (as well as the rest of the body), and a couple of worthy strategies here would be to avoid spikes in blood sugar (these are inflammatory), and ensure we have a decent amount of omega-3 fat (generally anti-inflammatory) in the diet and not too much omega-6 fat (generally inflammatory). Some oily fish and/or grass-fed meat in the diet and a general avoidance of processed foods and vegetable oils will go a long way to achieving this end.
In addition to omega-3 fats, other dietary elements which may quell inflammation include plant chemicals known as polyphenols which are found in foods such as fruits, vegetables, coffee and cocoa. One class of polyphenols that have attracted recent attention with regard to brain health are known as anthocyanins, found abundantly in berries such as strawberries, raspberries and blueberries. Another potentially beneficial polyphenol which goes by the name of resveratrol is found in red grapes.
The value of these nutrients and the foods that offer them was recently highlighted in a review published on-line in the British Journal of Nutrition [1]. The review points our attention to evidence that shows supplementation with fruit juice appears to have the ability to enhance brain function in the elderly.
Another recent review highlighted the fact that berries can enhance beneficial signalling in the brain [2]. And a small study found some evidence for benefits in learning and memory in elderly individuals after 12 weeks supplementation with blueberry juice [3]. There’s nothing conclusive about this study, but it might provoke larger, longer and better-designed studies which will provide better insight into the role of polyphenols in maintaining and even enhancing brain function.
In the meantime, I don’t think it would be a bad idea to include some berries (fresh or frozen) in the diet.
References:
1. Cherniack EP. A berry thought-provoking idea: the potential role of plant polyphenols in the treatment of age-related cognitive disorders. Br J Nutr 2012 Apr 5:1-7. [Epub ahead of print]
2. Miller MG, et al. Berry Fruit Enhances Beneficial Signaling in the Brain. J Agric Food Chem. 2012 Feb 3. [Epub ahead of print]
3. Krikorian R, et al. Blueberry supplementation improves memory in older adults. J Agric Food Chem. 2010;58(7):3996-4000
