September 7, 2012
Green tea leaves steeping in a gaiwan 盖碗 (credit: Wikimol/Wikimedia Commons)
It has long been believed that drinking green tea is good for the memory. Now Chinese researchers have discovered how the chemical properties of China’s favorite drink affect the generation of brain cells, providing benefits for memory and spatial learning.
The researchers, led by Professor Yun Bai from the Third Military Medical University, Chongqing, China, focused on the organic chemical EGCG (epigallocatechin-3 gallate), the major polyphenol in green tea.
EGCG can easily pass through the blood-brain barrier and reach the functional parts of the brain. While EGCG is a known antioxidant, the team believes it could also have a beneficial effect against age-related degenerative diseases.
Green tea increases neurogenesis
“We proposed that EGCG can improve cognitive function by impacting the generation of neuron cells, a process known as neurogenesis,” said Bai. “We focused our research on the hippocampus, the part of the brain that processes information from short-term to long-term memory.”
In humans, hippocampal neurogenesis declines with age, and this decline is involved in various neurological disorders, many of which are associated with cognitive deficits.
The team found that ECGC boosts the production of neural progenitor cells, which, like stem cells, can adapt, or differentiate, into various types of cells. The team then used laboratory mice to discover if this increased cell production gave an advantage to memory or spatial learning.
Treatment with EGCG increased the expression of “sonic hedgehog” (Shh) signaling pathway components in the adult mouse hippocampus. Left: control; Right: with EGCG. (Credit: Yanyan Wang et al./Molecular Nutrition & Food Research)
“We ran tests on two groups of mice, one which had imbibed ECGC and a control group,” said Bai. “First the mice were trained for three days to find a visible platform in their maze. Then they were trained for seven days to find a hidden platform.”
The team found that the ECGC treated mice required less time to find the hidden platform. Overall, the results revealed that EGCG enhances learning and memory by improving object recognition and spatial memory.
“We have shown that the organic chemical EGCG acts directly to increase the production of neural progenitor cells, in both in vitro tests and in mice,” concluded Bai. “This helps us to understand the potential for EGCG, and green tea which contains it, to help combat degenerative diseases and memory loss.”
“These findings warrant a general recommendation to consume green tea regularly for disease prevention and provide support that EGCG may have therapeutic uses for treating neurodegenerative disorders,” the researchers conclude.
Human epidemiological data show that green tea consumption is inversely correlated with the incidence of dementia, Alzheimer’s disease, and Parkinson’s disease.
The research is published as an open-access article in Molecular Nutrition & Food Research. It is part of a collection of articles bringing together high quality research on the theme of food science and technology with particular relevance to China.
Browse free articles from Wiley’s food science and technology publications including the Journal of Food Science, Journal of the Science of Food and Agriculture and Molecular Nutrition & Food Research.
UPDATE Sept. 9, 2012: Prof. Yun Bai responds to this question: “The paper mentions that ‘it is likely that a daily 1500–1600 mg bolus of EGCG in humans would achieve physiological levels.’ How many cups of tea does that correspond to?”
“I see someone said in the comments ‘it would take at least 50 cups.’ Of course, we need not to do so. First, I have to clarify the difference between green tea and coffee. Because when you have a cup of coffee, you must add new coffee and water to the second cup. But for green tea, the tea is always there, you only need to add water to make the effective components release. We know EGCG is about 10–15% the weight of green tea, so you need 10–15g [.4–.5 oz.] of green tea, and just add hot water, and the EGCG will be in the water.
“We plan to do some research on EGCG and disease, such as Alzheimer’s disease and diabetes, maybe from new target cells and molecules.”
- Yanyan Wang, Maoquan Li, Xueqing Xu, Min Song, Huansheng Tao, Yun Bai, Green tea epigallocatechin-3-gallate (EGCG) promotes neural progenitor cell proliferation and sonic hedgehog pathway activation during adult hippocampal neurogenesis, Molecular Nutrition & Food Research, 2012, DOI: 10.1002/mnfr.201200035 (open access)
Topics: Biomed/Longevity | Cognitive Science/Neuroscience