Inflammation
Research has shown that catechins have anti-inflammatory activity. Inflammation in the brain is associated with many neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, and multiple sclerosis. Investigators CK Glass and others concluded in the March 2010 issue of the journal Cell, “Although inducers of inflammation may be generated in a disease-specific manner, there is evidence for a remarkable convergence in the mechanisms responsible for the sensing, transduction, and amplification of inflammatory processes that result in the production of neurotoxic mediators.”1 They also questioned if inhibition of inflammation pathways will successfully reverse or slow the disease process.
Oxidative Stress
Green tea catechins deliver strong antioxidant capability to brain neurons. Oxidative stress produced by amyloid beta peptides (Abeta), long chains of amino acids, is involved in the development of Alzheimer’s disease.
Scientists from the University of California studied whether green tea catechins would prevent cognitive impairment in an animal model of rats afflicted with Alzheimer’s.2 The green tea catechin formulation consisted of 63% epigallocatechin-3-gallate, 11% epicatechin, 6% (-)-epigallocatechin and 6% (-)-epicatechin-gallate. The treatments, randomly assigned, were either 0.0% of the catechin formulation or 0.5% of it.
Following 20 weeks of treatment the rats receiving 0.0% catechin formulation were divided into 2 groups. One group was given a solvent that dissolves Abeta and the other group was infused with Abeta. The 0.5% catechin formulation group was split in half randomly and given the same 2 treatments, one group with the Abeta solvent and one with extra Abeta infused in them.
After 26 weeks of being given the catechin formulation the rats were put in an 8-armed radial maze to assess behavioral changes. The results they obtained suggest that long-term administration of green tea catechins provides significant protective benefits against Abeta-induced cognitive impairment by increasing antioxidative defenses.
Learning and Memory Loss
Research has documented that flavonoid-rich foods are effective at reversing age-related deficits in learning and memory in animals and humans. A study from Peking University in China tested whether flavonoids could also deliver preventative effects on aged animals.3
Mice that were 14-months old (that’s old in a mouse’s lifespan) were given either 0.025%, 0.05% or 0.1% green tea catechins in their drinking water for six months, until the mice were 20 months old. The two higher doses of catechins prevented age-related spatial learning and memory decline as evaluated by running through a water maze. Brain chemistry was evaluated after the experiment was finished and the 0.5% and .01% catechin treatments resulted in the prevention of reductions of two proteins which suggested that catechins may influence synaptic structural changes related to the hippocampus.
The most current information about the effects of flavonoid-rich foods and beverages on a variety of neurological disorders comes from JP Spencer.4 The review has been approved for publication but is not yet in print. Flavonoids limit neurological degeneration in many disorders and they also prevent or even reverse deteriorations in cognitive performance. This is carried out by flavonoids through several mechanisms. These include the potential to protect neurons from injury by neurotoxins, an ability to minimize neuroinflammation and the potential to improve memory, learning and cognitive function.
Historically the antioxidant ability of flavonoids was thought to be the sole cause of their positive activities on the brain. More recently the benefits appear to be caused by 3 separate processes. One is the enzyme-activated pathways that regulate survival factors and gene expression, second in the ability to improve blood circulation in the hippocampus and the third is their ability to destroy neurotoxic species and pro-inflammatory agents. Spencer concluded by describing how the 3 processes likely are responsible for the observed neurological effects.
1Mechanisms Underlying Inflammation in Neurodegeneration. Glass CK, Saijo K, Winner B, Marchetto MC, Gage FH. Cell. 2010. 140(6):918-934.
2Green tea catechins prevent cognitive deficits caused by Abeta1-40 in rats. Haque AM, Hashimoto M, Katakura M, Hara Y, Shido O. J Nutr Biochem. 2008.19(9):619-26. Epub 2008 Feb 15.
3Long-term administration of green tea catechins prevents age-related spatial learning and memory decline in C57BL/6 J mice by regulating hippocampal cyclic amp-response element binding protein signaling cascade. Li Q, Zhao HF, Zhang ZF, Liu ZG, Pei XR, Wang JB, Cai MY, Li Y. Neuroscience. 2009. 159(4):1208-15. Epub 2009 Feb 11.
4Nutrition Society Silver Medal Lecture Beyond antioxidants: the cellular and molecular interactions of flavonoids and how these underpin their actions on the brain. Spencer JP. Proc Nutr Soc. 2010. 17:1-17. [Epub ahead of print].
