Green Tea - worthy of "Smart Drug" label?
Room For One More?
In the Smart Drugs chapter of SYBO we argued that of the various nootropics available in this day and age it makes sense to give preference to substances that have been around for eons rather than the new kids on the block. This really is the only way you can enjoy the benefits without having to worry about the potential unknown long term problems and side effects.
The brain benefits of regular coffee drinking were described, but due to space limitations we were only able to discuss a few other substances. This month’s blog highlights some of the many published studies that have indicated a wide variety of health benefits associated with regularly imbibing green tea - something that people have indeed been doing for hundreds of years.
Green & Black
Camellia sinensis is the name of the plant that gives us white, yellow, green, black and oolong teas. Black tea has more than twice the amount of caffeine as green tea, whilst green tea has more polyphenols (the very antioxidant substances that mop up all those dangerous free radicals). The difference in concentrations of these substances can be accounted for by the fact that black tea requires fermentation before preparation – which increases the caffeine content and decreases the polyphenol content – whilst green tea is prepared from unfermented leaves.
All The Tea In China
Green Tea has been used in traditional Chinese and Indian medicine for thousands of years where it has been exploited for it’s stimulant, diuretic and astringent properties; not to mention improving heart health, flatulence and body temperature regulation. The stimulant effects are thanks to the alkaloids contained within the tea leaf including caffeine, theobromine and theophylline. As green tea contains about half the caffeine of black tea and MUCH less than a cup of coffee, dosing yourself with green tea throughout the day is much less likely to disrupt your sleep come bedtime than the other options.
Typing “green tea” into an internet search engine yields a huge number of websites dedicated to promoting the ubiquitous benefits of regular green tea ingestion to improve the effectiveness of exercise, improving weight loss and even helping to manage diabetes. Of course its always difficult to know which sources you can and can't trust. Hard data is required to establish whether green tea really does help to ameliorate symptoms of the various complaints for which it has been traditionally recommended.
Is Green Tea Really Good For You?
Yes! When individual research studies are published in a peer-reviewed scientific journal they can provide evidence to support or reject any particular scientific hypothesis, but a single study cannot "prove" or "disprove" any given theory. Meta-analyses are much more powerful in this regard because they look at many different studies all investigating similar hypotheses. If, despite being conducted on a completely different group of subjects, often in a completely different location and undertaken by a different group of researchers, they all point towards the same conclusion this provides for a much more powerful argument to support, or refute, any given claim when the consensus points to a benefit. Just looking at the meta-analysis data it has been confirmed that green tea is effective at lowering blood pressure, reducing risk of several different cancers and improving cardiovascular/metabolic health, to name but a few.
Any Brain Benefits of Green Tea?
Drinking green tea has long been associated with relaxation and, indeed, scientific investigation has now backed this up. Epigallocatechine-3-gallate, the most active of the tea polyphenols (known collectively as “catechins”) is found in much higher quantities in green tea than other teas and is known to inhibit an enzyme that converts cortisone to cortisol. Cortisol is a so-called stress hormone and cortisone the inactive form. By preventing the enzyme in question – 11 beta-hydroxysteroid Dehydrogenase Type 1 – from doing its job, the active ingredient of green tea is able to reduce levels of the stress hormone. (In case you were wondering, the other 5 catechins are: catechin, gallaogatechin, epicatechin, epigallocatechin and epicatechin gallate).
Can Green Tea Can Improve Cognition?
Yes! Anecdotal accounts of the brain benefits of regular tea drinking in the elderly inspired research to establish whether green tea really could improve cognition. Over the last ten years huge amounts of data have been generated on this topic. The more green tea a person consumes, the lower prevalence of cognitive impairment (Full article available for free). Early research trying to ascertain the mechanism by which such benefits are realised demonstrated that spatial cognition was improved in rats that drank water infused with polyphenols from green tea (full article available for free).
In the last few years experiments dosing healthy, younger humans with green tea versus placebo have demonstrated an increase in functional connectivity between frontal and parietal brain areas during a working memory task (Full article available for free). Bearing in mind that improvements in working memory can translate into better fluid intelligence and therefore a higher score in the IQ test – swapping green tea into your daily hot drink regime might make sense for your brain’s sake as well as your body’s.
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