Green tea is the second most consumed beverage in the world. Its health benefits have been touted for centuries, yet it is only relatively recently that scientific investigations have been conducted to see specifically what benefits it can give and the mechanisms behind them.
Studies into the effects of green tea largely look at catechins, a type of polyphenol found in large amounts in this beverage. They are high in antioxidants, and have been shown to display a range of beneficial properties including:
- Antimutagenic
- Antidiabetic
- Anti-inflammatory
- Antibacterial
- Antiviral
There are four main catechins found in green tea as listed below:
- (-)-Epicatechin
- (-)-Epicatechin 3-gallate
- (-)-Epicatechin 3-gallate and
- (-)-Epigallocatechin 3-gallate (EGCG)
The catechin EGCG forms about 50% of total polyphenols in green tea and is thought to be one of the major contributors of green teas range of benefits. It is also the one most studied and is often sold as a separate supplement on its own.
Green tea also contains a range of other compounds such as caffeine, vitamins and trace elements, which could also contribute to some of the beneficial effects seen, although likely to a lesser extent.
Green Tea and Longevity
Green tea has such a wide range of benefits that it wouldn’t be too farfetched to assume it would have an effect on overall lifespan. Indeed some studies have looked into this, including those by Nakachi et al. (2003) and Ruan et al. (2013).
Nakachi et al. showed that increased green tea consumption lead to a delay in cancer onset and an increase in lifespan. The best results were seen in those who consumed > 10 cups of green tea a day (which is quite a lot! But cup sizes are 150ml per cup, not the 240ml US standard cup unit). This is the equivalent of 2-2.5g of green tea extract or 400-750mg tea polyphenols. Positive results were still seen in those who drank less than this amount however. Overall it seemed to show that modest increase in life expectancy (around 2-3years) with consumption of a reasonably high amount of green tea.
Ruan et al. is a more recent paper that looked investigated risk of mortality in Chinese individuals. It took survey data from around 60 years of age, and compared it to follow-up survey data at 80+ years of age. They showed that frequent tea drinking (not specifically green tea, but other kinds such as the black tea ‘Pu Er’) from 60 years old and at follow up when the subjects were 80+ years old resulted in a mortality reduction of 10%.
Whilst the majority of tea mortality studies are on Eastern populations, there are some that have looked at multi-ethnic populations such as the 2013 study by Gardener et al. which showed an inverse relationship between tea consumption and all-cause mortality. That is, more cups of tea drunk per day resulted in decreased mortality rates. Drinking two or more cups of tea a day was also associated with protection against non-vascular causes of death and cancer.
Which green tea to buy?
Most green tea is probably going to give you an overall positive health benefit in the long term, so you could just buy whatever is convenient for you (e.g. from the supermarket). However since this is a long term health strategy I feel it worth mentioning certain caveats associated with some sources of green tea.
The plants that tea leaves come from (Camellia sinensis) have a bit of a drawback in that they have a relatively high uptake of heavy metals (such as lead) from soil. This means it’s important to source tea from regions which have low levels of pollution and soil contamination.
Also important is how far away the tea plantation is away from major highways. The closer to a major road the higher the levels of lead present in the tea.
Most of the studies I’ve read show the commercially available green tea tends to have lead levels below the minimal allowed threshold set by governments, so generally there isn’t too much of a risk. But as I mentioned, if this is going to be something you decide to take habitually for the benefits it offers, it is best to choose wisely.
Another factor to consider is antioxidant content, which varies significantly between brands and countries of origin. There is good evidence to show that loose-leaf green tea from Japan has antioxidant content significantly higher than your common tea bag. Loose leaf tea in general seems to offer more benefits than most supermarket teabag styles.
Unfortunately most tea suppliers don’t advertise antioxidant or heavy metal analysis results, so trying to find a good source of tea was a bit challenging. However, with a bit of perseverance I managed to find one that met my requirements – Sugimoto Tea Company, whose tea primarily comes from tea plantations in Shizuoka, Japan. They don’t advertise test results directly on their website, but contact them by email and they’re more than happy to provide analysis results. I won’t give specifics in case the results aren’t allowed to be published, but the level of lead in their leaves are amongst the lowest I have seen reported in studies, and they have a high level of EGCG and other vitamins in their leaves. Basically the perfect combo, low/negligible contaminants and high levels of nutrients, just what we’re after.
Here is a link to one of their teas on Amazon, which has now become my daily standard: SA Japanese Green Tea Sen Cha.
They have a number of other green teas, most of which come from the same plantation in Shizuoka, so health benefits from other varieties should be similar. So if Sencha isn’t your thing, feel free to try out something else they have!
Brewing Guide
If you’re not used to drinking loose leaf green tea and not sure how to go about it, I recommend using something like the teacups from Bodum. They make it super convenient to steep your tea leaves and reuse them since the lid turns into a stand for the steeping basket once you’re done (you can generally reuse loose leaf tea leaves up to 3 times!).
Brewing instructions vary depending on the specific tea, so follow the manufacturers guide on the packet first and then alter that as you see fit.
For a single serving of the Sencha tea I recommended, use half a tablespoon of tea leaves in 5 oz of water. Then steep at 175°F (80°C) for 30-60 seconds.
Green tea is looking like a great way of improving ones health and lifespan, and it’s a rewarding experience to boot.
Here’s to your longevity!
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