Green Tea on the Brain

Find out what the Chinese have known for ages -- green tea is great for your brain.

By Anne Becker, published on June 10, 2003 - last reviewed on October 14, 2005

If you haven't traded in your morning latte for a grande green tea,
you're missing the boat to good health. It's no secret that green tea
bolsters the body in many ways. But did you also know the same components
of green tea also boost the brain?

Take polyphenols, for instance. These phytochemicals, which give
green tea its bitter taste, are powerful antioxidants that have been
associated with preventing cancer and heart attacks. Recent research has
also shown they may help maintain positive mood states and protect
against Parkinson's disease and other brain disorders.

A study from the University of San Francisco found that the
polyphenols in green tea can boost availability of the important brain
substance dopamine in the areas where it's needed. Dopamine is a
signaling substance in brain circuits that are crucial to creating
positive mood states.

It is involved in transmitting signals of reward and motivation and
in helping muscles move smoothly. Dopamine production goes awry in the
brains of Parkinson's patients, leading to the muscle rigidity and
tremors associated with the disorder.

Researchers in the study measured levels of dopamine in mice before
treating some of them with polyphenols. They then injured the specific
neurons linked to Parkinson's disease in all of the mice and measured
dopamine levels again. The mice treated with polyphenols appeared to have
been protected against toxic elements that may be linked to this

Other studies in animals show that the polyphenols in green tea
also help the brain and body maintain a steady supply of their chief
fuel, glucose. Polyphenols influence glucose metabolism in part by
helping the body regulate sensitivity to the hormone insulin. Compounds
in green tea enhance insulin sensitivity, keeping the brain running
smoothly on steady levels of glucose.

Tannins are another important set of compounds found in green tea.
They too have also been shown to have brain boosting benefits: they may
prevent the brain damage that occurs after strokes and other brain

Tannins, like many other beneficial substances in plants, are
natural compounds produced by tea leaves in the wild to keep animals from
devouring the growing plants. It now turns out that one of the tannins
found in tea leaves, gallotannin, helps the body's own DNA repair system
and keeps it working in the brain despite damage that occurs during

Under normal conditions, the DNA repair system in the brain goes
into overdrive in the aftermath of stroke, and instead of helping to
repair brain cells it causes them to die. But researchers at the
University of California at San Francisco found that if they surround
injured neurons with the gallotannin found in green tea, it is highly
effective in preventing neuron death.

This doesn't necessarily mean that consuming large amounts of green
tea would be sufficient to repair brain damage in stroke victims. The
amount of gallotannins found in green tea is negligible compared to the
large amount used in the study.

But researchers hope to harness and synthesize the substance found
in green tea and use it to help stroke victims. In the meantime,
consuming green tea can help keep your body and brain working at its
steady best.