In a blog post Dec 2011, (Neurotrophins are brain fertilizers) I talked about the importance of neurotrophins like brain-derived neurotrophic factor (BDNF) in protecting and healing the brain. BDNF works by changing how neurons work through their signaling pathways. These signaling pathways are important for turning neuronal activities on or off thereby increasing or decreasing the production of chemicals important for function. These pathways are not only important for healing but also important for the formation of short and long term memory. Research in animals over the past 10 years suggests that phytochemicals, especially flavonoids, may affect some of the same signaling pathways involving BDNF thereby influencing memory. The logical question is do berries, spinach and other flavonoid–rich foods make us smarter? Do they keep our brains young?
In one study conducted in the UK (Williams and group 2008), they showed that a diet supplemented with 2% dried and powered blueberry improved memory in old rats. Young animals were compared with old animals and with another group of old animals fed the blueberry diet for 12 weeks. It was interesting that old animals had less than half the levels of BDNF in the brain’s memory center than the young animals. Blueberries restored BDNF levels in the brains of the old rats to the same level as the young. Furthermore, the benefits of the blueberry diet emerged after only 3 weeks of supplementation.
In another study by Bickford and group in Boston (Brain Research 2000), older animals fed diets supplemented with either spinach, strawberry or blueberry improved performance on a motor coordination and learning task. They were able to measure the function of synapses in the cerebellum (a part of the brain important for coordinating movement) and found that all the diets improved the responsiveness of the neurons to stimulation.
There has not been much further work in this field however I think it is interesting and since blueberries are not likely to be harmful, it may be sensible to add them to one’s diet. It is difficult to determine how much blueberries one would have to eat to have benefit. From the UK study, 1% of our diet may correspond to ½ to one cup of berries. The Boston study added 1 g to the diet of a 250g animal- which would be about .4% of the body weight or perhaps 0.6lb per day for a 150lb person.