Tea, the drink you need to think.

Researchers now believe that tea consumption may help support cognitive function. In Japan, 1003 Japanese subjects aged 70 and older were given a self-administered questionnaire that included questions about their green tea consumption. Results showed that higher consumption of green tea was associated with a lower prevalence of cognitive impairment.1

In an earlier study conducted in 2005, researchers investigated the role of green tea consumption had on the progression of Alzheimer’s disease. Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by deposition of beta-amyloid plaques in the brain. The researchers showed that nerve cells of mice treated with EGCG (the main polyphenolic constituent of green tea ) generated as much as 54% fewer beta-amyloid protein than nontreated mice nerve cells.

As good news as this is for people concerned about memory loss, it’s important to understand that not all components of green tea is beneficial to the brain, and in fact, may be detrimental. The researchers found other green tea antioxidants actually decreased EGCG's ability to reduce beta-amyloid protein production. So drinking green tea alone may not be enough to fight Alzheimer's disease.

According to one researcher involved in the 2005 study, he suggested that a green tea extract with a high concentration of EGCG would be needed to override the detrimental effect of other flavonoids found in green tea.

Researchers say that in order to receive benefits of green tea, humans would need dose of about 1,500 to 1,600 milligrams daily. That dose has already been studied in humans and found to be safe.2

References:
1. Am J Clin Nutr, Vol 83, No. 2, 355-361, Feb 2006.
2. Journal of Neuroscience, September 21, 2005, 25(38):8807-8814.