Tea has a mighty reputation as a healthy drink, but is there science to back up those claims?
In this article, learn about the latest research on tea and health, including some new ways to understand how tea affects the body, as presented at the 2019 UC Davis Global Tea Initiative.
As far as drinks go, tea is always seen as the healthy option.
If you’re a tea drinker, you’ve probably had family members ask what teas to drink to solve this problem and that. They’ve seen all the miraculous teas on the market. Weight loss teas. “Detox” teas. Lose-20-lbs-and-also-cure-cancer teas.
Tea’s been put on a pedestal for all sorts of curative properties, but what research do we have to back those claims?
While tea isn’t the magical cure-all that the market wants it to be, science is definitely finding links between tea and better health.
So far, we’ve found that L-theanine, an amino acid found only in tea, is linked with better mental performance, while catechins, one of the most abundant compounds in tea leaves, may help with cardiovascular health and with weight loss.
As interest in tea builds and more research is done, we can start to build a more holistic view of how tea affects our health. Some of that latest research was presented at this year’s Global Tea Initiative at UC Davis, California, as part of its project to build the first ever Tea Institute in the United States.
For now, the university is laying the ground-work for its tea program, including a dedicated tea garden space and tea-focused sensory evaluation labs, but while we wait for the day we can all get tea degrees, this annual conference is an exciting meeting ground for tea researchers, experts, and enthusiasts to share the latest in the tea world.
This year’s theme: Tea & Health: Mind, Body, and Spirit, and it offered exciting developments in tea research, with some surprising new approaches.
It offered up some exciting new developments for the world of tea and medicine, especially with the promise of the research that will soon be conducted right on campus.
Here are some exciting new ways we’re thinking about tea and health, based on the presentations at the conference.
Drinking tea could change the microbes in our digestive system
The gut microbiome is big news in health lately.
We’ve found that our digestive system contains trillions of tiny microbes, and each species has the ability to influence our health, diet, and even mood in complicated ways.
Some microbes influence the weight on the scale, while others have effects on our overall immunity.
And like fingerprints, everyone’s microbiomes are a little different, which helps explain why some of us are never sick while others are always at the doctor’s office.
The make-up of your gut microbiome is influenced by your diet and environment. As it turns out, when we drink tea, we could be changing those microbes in big ways.
According to Dr. Yvonne Wan, professor at the UC Davis School of Medicine, tea can act like a probiotic, just like Yakult or cultured yogurt. Drinking tea can encourage the growth of certain beneficial microbes, while eliminating other potentially harmful microbes.
In her research, Dr. Wan studied rats fed on a western diet. These rats saw a change in their gut microbiome, and problems with obesity, inflammation, and high blood sugar.
When they were fed with EGCG, a catechin found in green tea, the rats’ gut microbiomes changed again. The EGCG helped promote enterrococceae, verrumicrobiaceae, and Akkermansia muciniphilia – basically good microbes which help with weight loss, fat loss, and lower blood sugar.
EGCG also reduced baij, a bacteria that’s linked to human polyps and colon cancers.
Different teas could also have different effects on the gut microbiome.
While green tea is high in EGCG, other teas, like dark tea (also known as post-fermented teas, or heicha), are low in EGCG but high in metabolites, a product of fermentation, which can help improve digestion and maintain blood sugar.
There’s one dark tea in particular that could be promising to study. In China, a dark tea called Fu Zhuan is produced that is so rich in yeast microbes that they can be seen with the naked eye.
This yeast, called Aspergillus cristatus (or Eurotium cristatum), grows on Fu Zhuan tea and can even be seen thriving or dying back based on the season. It’s nicknamed jin hua, or “golden flowers”.
We can imagine that drinking a cup of Fu Zhuan probably makes a pretty big splash in the gut microbiome!
It’s also no coincidence that Dr. Wan is an avid Fu Zhuan enthusiast.
While Dr. Wan hasn’t released research on Fu Zhuan, she explained that Central Asian nomads once relied on Fu Zhuan tea to help with digestion, thanks to their heavily meat-based diets. They believed that skipping tea would risk constipation, then eventually inflammation and chronic pain.
Hopefully we can see more research in the future from Dr. Wan.
Tea might change the way our genes are expressed
We know that we’re stuck with the DNA inherited from our parents: about 50% from Dad, and 50% from Mom. That determines things like our eye color and hair color, but also things like a higher risk for heart disease or cancer.
We can’t change our genes, but we may be able to change the way they’re expressed, based on triggers in our diet and environment. In scientific lingo, this is called epigenetic expression.
Some triggers encourage disease, while others delay or prevent disease. In theory, we could find the right triggers to “turn off” the genes for cancer and Alzheimer’s.
Luckily for tea drinkers, it looks like tea is on our side in the game of epigenetics.
According to Dr. Weronica Ek from Uppsala University in Sweden, tea may help with healthy gene expression.
In her research, she tracked tea and coffee consumption in European populations, looking for correlations with gene expression.
Dr. Ek found that while coffee had no effect on gene expression, tea did. In particular, tea was related to 28 regions in our DNA, including those related to fighting cancer and for regulating blood sugar.
Interestingly, the link between tea and gene expression was found only in women. According to Dr. Ek, this might be because women consume higher amounts of tea than men, but the reason for this gender divide is unclear.
It’s also unclear if the type of tea consumed had an effect, if any, on gene expression. The team assumed that most folks were drinking black tea, the most popular type in Europe, but this data wasn’t collected in the study.
The findings aren’t perfect, and it’s important to remember that research often finds correlation, not causation, so we’re still not 100% sure what tea is doing to our long-term health.
It’s a great start though, and great news for folks whose family health history is a little scary.
Who knows – our daily cup of tea could help us turn the tide against our own genetic cards… better than coffee can, at least!
The bridge between tea traditions and science
Perhaps the most exciting development in tea research is the meeting of two worlds: hard science, and ancient tea knowledge.
As much as I’m excited that we can finally study tea in a scientific, evidence-based way, it’d be a waste to dismiss what we know from traditional tea culture, which have considered tea to be medicinal for thousands of years.
The tea institute at UC Davis could be that bridge between old and new, and it shows in the conference. The chosen presenters included not just scientists and hard-line academics, but also cultural experts to share information on tea that might be considered “esoteric” by some, but that’s just begging to be explored and tested.
Mr. Wing Chi Ip, from the famous LockCha Teahouse in Hong Kong, shared tea as understood from Chinese tea philosophy. For example, tea picked before the summer is believed to be better for the body, while tea picked later in the year is less potent.
Also, tea is considered to be a yin food, which registers as “cold” in the body. In contrast, other foods might be more yang, which are more warming.
In traditional Chinese medicine, it’s important to have balance of yin and yang, so it’s believed that people who already naturally cold shouldn’t drink too much tea. This could differ based on the tea too, since green tea is considered more “cold” while roasted teas, like houjicha or Wuyi oolong, are more “warm”.
Another old favorite in the tea world is kombucha, a fermented drink that’s been made in various Asian cultures for a long time.
Folk knowledge says that kombucha helps with digestion and immunity, and that belief has spilled over to the West, where kombucha is now the fastest growing Ready-to-Drink category in tea.
Dr. Wan (our gut microbiome expert) also pointed out that elderly women who lived around Chernobyl had better survivability if they drank kombucha.
However, there is still no scientific study that supports the benefits of kombucha, so there’s still so much room for research in the tea world, especially to test and confirm these old tea beliefs.
This is just the tip of the iceberg for tea research, with interest in tea growing by the day.
With time, we’ll develop an even better understanding of tea and health, giving us more solid evidence to prove what we already intuitively know – that tea is, in its own way, a form of plant medicine.