Teacology

Tea, with an Ecological Approach


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Tea: Bioactivity and Therapeutic Potential – A Book Review

Back in 2009, while researching the health properties of tea, I came across an interesting book, titled Tea: Bioactivity and Therapeutic Potential.  Here I will share a review of this book, but I also want to highlight a key point about tea and health that I found in this book, that I think others may find interesting.  This review is informed in large part by how what I read in this book fit and did not fit with various things I learned from my later research.

A purple book titled: Tea: Bioactivity and Therapeutic Potential

The Cover of Tea: Bioactivity and Therapeutic Potential

As its name suggests, the book focuses on tea and medicine, therapeutic uses of tea, rather than the more general tea and health, although there is certainly a lot of discussion of broader and long-term impacts of tea, such as through nutrition and public health.

This volume is a collection of research articles by different authors.  Although the ordering of the essays is about as logical as possible for weaving the book into a coherent whole, it is still a collection of disparate articles on different facets of tea and medicine.  This sort of structure lends itself more to looking up and reading one essay in isolation than reading the book straight through.  I skipped around and read the parts I found interesting and then returned it to the library.

This book is also interesting in that it is an English-language text, but it consists mostly of research conducted at Chinese institutions by Chinese researchers.  I find it offers a novel perspective from what is available in other English-language texts.  There is a lot of information that I have found in this book that I have not encountered in any other English-language sources.  It is a pretty dense, scientific text, and I would not recommend it to most casual tea drinkers, but scientific-minded tea lovers may find it more accessible and interesting.  Parts of the book require a working knowledge of basic biochemistry.

A Review of the Book’s First Essay, Titled “Tea and Health: An Overview”

The book’s first article is titled “Tea and Health: An Overview”, and is by Mia-Lan Chen, at the Chinese Academy of Medical Sciences and Peking Union Medical College.  As this was an overview, and among the most accessible of the pieces in the book, I read it more deeply and thoroughly than the other articles.

When I initially read this article, it seemed very informative and well-researched, although I have a critique below in which I mention some potential bias.  Although it focuses on tea and health, the article begins by going into the history of tea drinking, and explores this history through the lens of health.  This section of the article has some fascinating observations, among them, observing that tea drinking changes how people consume water in ways that can potentially benefit public health.

Tea Drinking and Public Health: The Importance of Boiling Water

In our modern Western society, we often take clean drinking water for granted, and we may forget that for much of human history, and still in many parts of the world, the water supply was or is a major vector for a variety of diseases, and the spread of diseases through water and the practices needed to maintain sanitation were poorly understood.  This essay asserts that when tea drinking became widespread, it resulted in the boiling of water becoming mainstream, which killed microbes present in the water, making it safer to drink.  This might have provided one of the most compelling “health benefits of tea” not only in ancient times but up until the advent of modern sanitation.

A pot of water boiling on a stove

Boiling water can promote public health by killing microbes in the water. Tea may have helped this practice become mainstream.

The above image is provided by Wikimedia Commons user Gran and licensed under CC BY 3.0.

A Possible Bias?

The rest of this essay goes through the chemical composition of tea, talking a little about how it relates to tea production, and then gives an overview of tea and health, as its name would suggest.

Some time after reading this essay and researching other sources on tea and health, I began to get a compelling feeling that the health benefits of tea had been overstated somewhat in this essay, and the potential health risks downplayed.  Granted, the health risks of tea consumption are mild, even relative to coffee, but the book made a bold claim about tea consumption showing no evidence of harmful effects even when consumed in very large quantities and this did not fit with my own knowledge or research.  The extent and certainty with which the article presented the various benefits of tea drinking also seemed to exceed that which I encountered in other sources.  I have not returned to this book though, so my impression of bias was just that–an impression or gut feeling, and I am not certain whether it would pan out if I subjected this article to more intense scrutiny.

Are you familiar with this book?

If you’ve read this book, I would be curious to hear your opinion or perspective on it.  I’d be particularly interested to hear people’s perspectives on my impression of pro-tea bias.  As a tea lover, I tend to worry that I myself may tend to be biased in favor of tea, so if I see something as being biased in favor of tea, it raises a red flag for me.

Here are some questions to think about:

  • Have you ever encountered the idea that tea drinking indirectly promoted or promotes public health through encouraging the boiling of water?
  • If you’ve read this book, do you think it exhibits any sort of bias in favor of tea’s benefits, or do you think it is more objective?
  • Do you think there could be possible cultural biases or economic factors at work influencing researchers in China to view tea in a more positive light?
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Adding Citric Acid to Teas or Herbal Blends

This post is inspired by an old post adding citric acid to teas, but it is much more than a rewrite of that post.

Most of us are familiar with the practice of adding lemon or lemon juice to tea.  The effect of adding lemon juice is most evident in black tea, producing an immediate chemical change in the tea, usually resulting in a noticeably lighter color, and a cup that is somewhat less bitter and astringent, but more sour.  A practice that is less familiar is one that some mainstream tea manufacturers do, particularly those dealing in herbal blends, which is adding citric acid to teas.

The following photo is by André Karwath and is licensed under CC BY-SA 2.5.

A whole lemon and a sliced lemon, white background

Citric acid is responsible for the characteristic sour flavor of lemons and lemon juice.

I was genuinely surprised when I first saw citric acid on the ingredient list of a packaged box of herbal teas.  This would not so much surprise me for a bottled or “ready-to-drink” tea, but for a tea bag, it was quite unexpected.  I think of herbal teas as being something that is made strictly from dried plant ingredients, so I do not expect to find an added pure chemical ingredient.  Some of the mainstream teas that include added citric acid are Celestial Seasonings’ Country Peach Passion and Lemon Zinger, and Tazo’s Passion and Calm.

On Citric Acid – The Chemical and its Production

Citric acid is a common organic acid that is named (and best-known) for being the main acid that imparts the characteristic sour flavor to citrus fruits like lemon and lime.  It is a common and safe food additive, used to impart a sour flavor to food and drink.  It can be isolated from citrus fruits, but is also commercially produced on a larger scale by using mold, such as Asperillus niger, to ferment sugar.

Citric acid is a pretty basic chemical in biochemistry.  It plays an essential role in all aerobic (oxygen-respiring) organisms through the citric acid cycle, also known as the Krebs cycle.  Here is a molecular diagram, for the chemistry-minded among us:

Graphical representation of the citric acid molecule

A graphical representation of the citric acid molecule

As someone who is highly skeptical of highly refined food additives, especially ones that consist of a single chemical, a natural question for me is: is added citric acid safe?

There’s not much to worry about with respect to citric acid, beyond its sourness.  Everything I’ve ever learned about it has taught me that it’s safe as a food additive.  However, the acidity itself though can sometimes be a concern.  For example, acidic drinks can soften tooth enamel, so it’s not a great idea to brush your teeth directly after drinking a cup of sour-tasting herbal tea.  Acidic drinks can also sting or irritate the mouth, especially if there is already a sensitive area like a burn.

Added Citric Acid is Not Necessary to Make Herbal Blends Sour

When I first discovered that some herbal teas contained added citric acid, I was curious to see which blends contained it and which did not.  One thing that surprised me was that the blends that were most sour did not necessarily correspond to the ones with added citric acid.

As examples, Celestial Seasonings Country Peach Passion and Tazo Calm are not among the most sour of herbal teas out there, but the famously sour Red Zinger does not (although some of the Zinger series blends do).  This is because Red Zinger uses Hibiscus as the main ingredient.  Hibiscus on its own, when brewed as an herbal tea, is intensely sour.

This photo was contributed by Popperipopp and is licensed under CC BY 3.0.

Dried hibiscus sepals, pink and dark purple in color

Sepals of the Hibiscus sabdariffa plant are a whole ingredient that can be added to tea or herbal blends to impart a sour flavor.

Why do tea companies not always use hibiscus?  It may be due to its color, and its peculiar flavor and aroma.  Even small amounts of hibiscus impart an intense purple-red color that may not be desirable in all blends.  But hibiscus also has a characteristic aroma, which I describe as being somewhat like berries but also a lot like cooked fruit or jam.  I sometimes find this aroma a bit overpowering, so it makes sense that companies would want to look for other ways to make their blends sour.

What do you think?  How do you feel about added citric acid in tea or herbal blends?

Here are some questions that you can answer in the comments, or in a follow-up blog post of your own.

  • Did you know that some tea companies add citric acid to their herbal blends, or is this a new realization for you?
  • Are you bothered by the practice of adding citric acid rather than relying on whole ingredients like herbs or spices, or is it fine with you?
  • How do you feel about sour-tasting blends in general?  Do you tend to like or dislike them?  How sour is too sour to you?
  • Do you ever add lemon to your tea?

My personal opinion?  I don’t have a big problem with added citric acid, but I think I would prefer blends made from whole ingredients.  Either way, I don’t like sour tastes much in my tea or herb tea.  I avoid both added citric acid, and blends that have too much hibiscus or other naturally-sour whole ingredients.