Among the many benefits of green tea we will get into this year, we wanted to start with how it affects one of the biggest growing challenges we face today: mental health. Some conditions are genetic, some are caused by external factors, and sometimes, we just need a little help with our memory or mood. Regardless, there are some basic actions we can take to help face these challenges and even improve them over time. For starters, how can drinking green tea help combat and protect us from mental health issues?
*Short on time? Scroll down for 5 quick takeaways.
Drink Away Dementia
As we age, our ability to think, remember and reason can get weaker. However, simply growing forgetful with age, and developing dementia (e.g. Alzheimer’s, Parkinson's, etc.) are different. Small vessels in the brain become damaged over a long period of time. When abnormal proteins accumulate in certain parts of the brain, they damage healthy brain cells and cause them to die. In healthy people, the brain’s immune function removes these abnormal protein plaques by responding to the inflammation they cause. But when this response doesn’t happen properly and the inflammation continues for a long time, the brain cells become damaged and dementia takes root.
Catechins are a natural antioxidant found in fruits, vegetables, and even wine and chocolate, but most abundantly in green tea. The main catechin in green tea is called EGCG (epigallocatechin-3-gallate). In one study, brain cells from the hippocampus (the part of the brain which regulates memory) were exposed to beta-amyloid proteins (Alzheimer’s plaques). The higher the exposure, the more brain cells died. When they added the green tea catechin EGCG, however, the brain cells' survival rate increased. This demonstrated the potent antioxidant effects of EGCG on the brain.
Because the brain is such an important organ in our body, it has a natural barrier that carefully screens what passes through from the blood into the brain (like a bouncer guarding the door of a VIP room). EGCG passes through the blood-brain barrier very easily (like a VIP). This allows it to act directly on the brain, and potentially improve the health of blood vessels and increase the supply of nitric oxide, which together could benefit cognitive function.
In some eastern countries where drinking tea is part of the culture, studies were done on the difference between those who drank green tea over time, and those who didn’t. The results showed that those who drank more green tea over a longer period of time were at lower risk of cognitive disorders. In other words, it's important to start drinking green tea regularly now in order to help protect against mental disorders later. *Remember, prevention is key for dementia.
Think Theanine
Another very important component in green tea is an amino acid called theanine. It is only found in some mushrooms and teas, especially green tea. Theanine has strong neuro-protective effects on brain cells. Like EGCG, theanine is another VIP to the brain, meaning it can easily pass through the blood-brain barrier. This direct access can allow it to improve neuroplasticity (the brain's ability to form new connections between neurons). In another study where mice were fed theanine twice a week, they showed increased BDNF*, resulting in improved memory and learning.
*BDNF: Brain-derived neurotrophic factor [which plays an important role in the survival and growth of nerve cells].
Theanine also helps lower stress hormone levels in the blood. When stress hormone levels are high, there is reduced potential for connections between neurons to improve and change. When stress hormone levels are lowered, it helps our neurons to form better connections. Basically, less stress hormones = better brain function. Theanine's effects on reducing stress and anxiety can be seen as yet another way in which green tea protects brain cells from stress and age-related damage.
The Calm Caffeine
In our Sleep blog, we explained that a substance called adenosine builds up in our bodies throughout the day. As we accumulate more adenosine, we become sleepy.
Caffeine molecules are similar in structure to adenosine molecules. When caffeine enters our body, it attaches to the adenosine receptors in place of adenosine, which then wakes us up. But when the caffeine wears off, all the adenosine that has been accumulating floods the receptors, and we suddenly feel very tired. This is the “caffeine crash” we sometimes experience. When the adenosine receptors are continuously occupied by caffeine molecules—that is, when we keep consuming caffeine—the body actually creates more adenosine receptors in the hopes of adenosine attaching to them. Indeed, now that there are excess receptors, adenosine does attach to some of them, and so we start to feel tired even with caffeine in our system. This is why we eventually need more caffeine in order to feel the same wakefulness.
Caffeine alone can cause anxiety through increased heart-rate and adrenaline release. Adrenaline (the "fight or flight hormone") is necessary at times, but has detrimental effects when released too frequently over a long period of time. However, green tea naturally contains a unique combination of caffeine, catechins and theanine. Why is this important?
Theanine's structure is similar to GABA (a neurotransmitter that prevents excitability in the nervous system) and has the same calming effects. Yet, studies show that unlike other anti-stress herbs, theanine does not cause drowsiness, and also keeps the awakening effects of caffeine under control. These calming and caffeine-modulating effects may be why many people report having less anxiety and improved sleep at night after drinking green tea throughout the day. Indeed, research shows that theanine reduces anxiety and also controls high blood pressure.
Now those who want the awakening effects of caffeine might think the theanine in green tea makes the caffeine too weak for them. But consider this study: when people ingested caffeine with theanine, they had faster reaction times, faster numeric calculation times, improved sentence comprehension, and increased alertness than when they had caffeine alone.
In another study, one group of people was given plain water before meditating, and another group was given water with theanine mixed into it. The group without theanine achieved alpha-waves in their brains (relaxed, focused, alert) 90 minutes into meditation. The group who had theanine, however, achieved the alpha-waves just 45 minutes into meditation, and with more intensity. It's no wonder green tea was consumed regularly by Japanese monks and samurai as early as the 12th century!
Similarly, consuming EGCG (the most abundant catechin in green tea) has been shown to increase not only alpha waves (restful, meditative state), but also theta waves (relaxed, daydream state), and even beta waves (alert, focused state) in the brain. In other words, it supports a relaxed and focused state of mind.
When the many components in green tea are extracted and studied separately, the raw studies show limited results in their benefits. However, all of these components are naturally formed to exist together in green tea, and many studies suggest a synergistic reaction in which they enhance each other’s beneficial effects on mental—and overall—health.
In Short:
- Dementia starts with prolonged inflammation in the brain. Green tea is anti-inflammatory.
- Consistent, long-term consumption of green tea can help protect against future dementia. Remember, there is no cure for dementia, only prevention.
- EGCG & theanine have VIP access to the brain. They improve brain function and reduce stress and anxiety.
- Green tea's theanine + caffeine = calm, focus, alert. And no caffeine crash.
- Before you reach for supplements: there is magic in the natural synergy of the benefits in green tea.
There is another very important factor that is deeply connected to mood and mental health: Our gut. Next time, we will cover that + some great tips (besides drinking green tea) on how to improve your mood and mind!
References
https://pubmed.ncbi.nlm.nih.gov/30273101/
https://pubmed.ncbi.nlm.nih.gov/31758301/
https://www.nature.com/articles/d41586-019-00398-1#ref-CR7
https://thebrain.mcgill.ca/flash/i/i_03/i_03_m/i_03_m_par/i_03_m_par_cafeine.html
https://www.mdpi.com/2072-6643/10/9/1201
https://pubmed.ncbi.nlm.nih.gov/20617284/
https://pubmed.ncbi.nlm.nih.gov/17013636/
https://pubmed.ncbi.nlm.nih.gov/18006208/
https://pubmed.ncbi.nlm.nih.gov/22127270/
https://pubmed.ncbi.nlm.nih.gov/28899506/
https://www.liebertpub.com/doi/pdf/10.1089/10762800151125092
