Hidden Treasure in Pu-erh Tea

Pu-erh Tea
Provides Statin Benefits

A little lovastatin and a lot of EGCG (from green tea)
can provide significant cardiovascular benefits
By Will Block

inding a pearl in an oyster is quite a thrill. You know that the oyster is going to be delicious (assuming that you like oysters), and you know that the occasional oyster will harbor a pearl within its glistening folds, but you never really expect to be so lucky as to find one. Things like that only happen to other people, right?

Imagine, then, how exciting it would be to find a small treasure in a place where there was no expectation of finding it. Something like that happened to researchers in China when they discovered, in 2003, that an unusual kind of tea called Pu-erh (pronounced poo·air) contains tiny amounts of a biochemical treasure that can help keep our cholesterol levels down and, therefore, our health and longevity prospects up.1*


*For an overview of this remarkable tea, see “Pu-erh Tea—Exotic, Aged, and Anti-Fat” in the June 2007 issue.


The “pearl” they found was lovastatin, one of the most effective cholesterol-lowering agents there is. Together with other members of the statin family, lovastatin is among the most widely prescribed drugs on earth. It was the only statin the researchers found in the Pu-erh tea. They did not, however, ascertain its concentration in the sample they were studying.

A Trace of Lovastatin—It’s a Start

Lovastatin
That oversight was rectified recently, using a sample of Pu-erh tea that came from the Yunnan province of southwestern China (the source of almost all Pu-erh) but that was not otherwise identified. Chinese researchers confirmed that lovastatin was the only statin present in the tea, and its concentration was 139 nanograms per gram (dry weight), or 0.00001.39% by weight—which is admittedly not much.2 That amount was obtained using ethyl acetate as the extraction solvent; when boiling water was used, the measured concentration was only 62 ng/g (dw).

Obviously the real concentration was at least 139 ng/g, but water did not extract as much lovastatin as ethyl acetate did (some other solvent might have extracted more). This illustrates how dependent some measurements are on the techniques used. But measured amounts of lovastatin in Pu-erh tea could also depend on many other factors—a topic to which we’ll return after a brief digression.

Health Benefits of Pu-erh Tea

Although different kinds of tea have different chemical compositions, all teas—by which we mean true teas (from the tea tree, Camellia sinensis), not herbal teas—have demonstrated a remarkably broad spectrum of health benefits. The authors of a recent paper on Pu-erh teas had this to say:3

In recent years, studies investigating health benefit effects of Pu-erh tea have shown effects on antioxidant, anticancer, lowering cholesterol, blood pressure, and blood sugar, and improving bacterial flora in the intestines.

Pu-erh tea has become best known, however, for its ability to inhibit an enzyme complex called fatty acid synthase (FAS), which is linked not only to obesity but also to cancer (elevated levels of FAS are found in a wide variety of human cancers). This suggests that Pu-erh could be an anticancer agent as well as an effective weight-control agent—especially if used in conjunction with a low-glycemic-index diet and a program of regular exercise. (See “Fighting Fat with Pu-erh Tea” in the July 2007 issue.)

Things that Can Affect the Properties of Tea

Like wine, tea is a complex beverage. Some aspects of its chemical composition—and hence its medicinal as well as sensory qualities—can vary widely, depending on factors such as the particular variety of tea, where it was grown (soil is a major factor), how it was cultivated, the year and season of harvest, the prevailing climatic conditions, and how the tea leaves were processed (a critical factor), blended, packaged, and stored before shipment.

Also playing a key role is the aging process. Aging? Of tea? Aren’t teas supposed to be drunk as young and fresh as possible? Well, yes, and much Pu-erh in China is drunk in the form of young, fresh, green tea. Most of it, however, is aged, like a fine red wine, and this is the form for which it’s renowned. Immediately after harvesting, the tea leaves are heated, lightly steamed, and compressed into small cakes weighing about a pound. The cakes are allowed to undergo a long, slow fermentation that adds depth and complexity to the tea’s character (it also turns the leaves black).

Fermentation—To Heat or Not to Heat?

This fermentation process is different from the one used to make oolong and black teas. In the latter process, the leaves ferment quickly “from within,” mainly by the action of their own enzymes, which are left intact by not heating them. With Pu-erh teas, the leaves are heated to destroy the enzymes (just as is done to produce green teas), but then they undergo a “secondary oxidation/fermentation” process, which is brought about by various microorganisms. This can take months, years, or even decades to reach fruition. The best such teas are so highly prized by connoisseurs that a single cake can fetch thousands of dollars.


Daily consumption of a
green tea extract containing
200 to 300 mg of EGCG can
provide pronounced cardio-
vascular and metabolic benefits.


The most prevalent microorganism found in fermenting Pu-erh teas is the fungus Aspergillus niger, but there are many others—and which ones are dominant in any given batch can make a big difference in the outcome. For obvious reasons, this is a matter of great concern to Chinese teamakers and scientists alike.

Chinese researchers recently investigated the effects of a variety of fermentation-inducing microorganisms on the levels of three substances in Pu-erh tea: lovastatin, gamma-aminobutyric acid (GABA), and polyphenols (as a class); they also measured antioxidant activity in the teas.3 We know why they were interested in lovastatin, but what about the other two substances?

GABA—A Neurotransmitter and Then Some

GABA is the most important inhibitory neurotransmitter in the central nervous system (CNS), where, among other things, it acts as a relaxant and stabilizer of mood disorders. This has the “side effect” of enhancing the immune system, which is notoriously susceptible to degradation by anxiety and stress.4 Moreover, GABA is believed (mostly from animal studies) to have a number of effects outside the CNS, including regulation of cardiovascular functions, inhibition of the metastasis of cancer cells, regulation of pituitary functions and growth hormone production, and modulation of renal function.

Polyphenols—EGCG Is the Star

Polyphenols are a large class of compounds known for their strong antioxidant properties in laboratory experiments (but not in animals or humans) and for a variety of demonstrable health benefits—probably owing to other mechanisms of action—when ingested by animals or humans.

One category of polyphenols is the flavonoids, and one type of flavonoids is the catechins, which are found primarily in green tea; they tend to be destroyed by the fermentation processes that produce oolong and black teas and Pu-erh tea (which has virtually none). Of the catechins, the most potent—and the most prevalent—is EGCG (epigallocatechin gallate), the compound that gets most of the credit for the myriad health benefits of green tea.

In Search of Better Microbes . . .

First, the researchers examined eight Pu-erh teas aged 0, 6, 10, 12, 12, 20, 20, and 25 years.3 They found that the lovastatin content increased steadily with age, ranging from nearly nil in the fresh tea to 513 ng/g (dw) in the 25-year-old tea (the GABA content also increased with age).* This is interesting, but it was not a fair test of the effect of aging on lovastatin content, because there were eight different Pu-erhs, not one Pu-erh at eight different stages of aging.


*The solvent used for the extraction was not stipulated.


For further testing, the researchers chose two of the Pu-erh teas, Ta-Huang-In and Ta-Hon-In, which are known for their exceptional quality. They took samples of fresh leaves from these two types, sterilized them in an autoclave, inoculated them (individually) with 30 different strains of fungi and bacteria that are known to predominate in the Pu-erhs of Yunnan province, and allowed them to ferment for 7 months.

Their aim was to find the microorganisms that would provide the best combination of sensory qualities (color, aroma, and taste—which is why people drink tea in the first place) and medicinal qualities, as reflected in the concentrations of the substances mentioned above.

. . . To Produce More Lovastatin

Teas brewed from these samples were then evaluated for sensory quality by nine experts, and the top 15 samples, representing seven different microbial strains, were selected for further testing. There were two clear winners: the bacteria Streptomyces bacillaris and Streptomyces cinereus (there are several hundred species in this genus, many of which produce valuable antibiotics).

As before, the lovastatin concentrations increased with age, up to about the 6-month limit of the study, at which point most of them seemed to be leveling off or even declining slightly, at values of a few hundred ng/g (dw). With S. bacillaris and S. cinereus, the lovastatin concentration soared from nearly nil to 2183 and 4160 ng/g (dw), respectively; these values were about 4 and 8 times greater, respectively, than the value of 513 measured previously in the 25-year-old sample of Ta-Hon-In.

Although the lovastatin still existed only in trace amounts, this study showed that, at least in the Pu-erh samples tested, its concentration rose rapidly during the first six months, and it depended strongly on the microbial strain. That’s useful information for scientists who want to develop better methods, whether through applied microbiology or genetic engineering, for producing teas that are still delicious but even more healthful than they already are.

How Much Tea? How Much EGCG?

Tea is, in fact, such an extraordinarily healthful beverage that summarizing its many benefits is a challenge. One part of the challenge was met recently in a review article entitled, “Effects of Green Tea and EGCG on Cardiovascular and Metabolic Health.”5 Skipping the large number of laboratory studies, the author focused on the many animal and human studies demonstrating a wide variety of benefits in terms of cardiovascular disease and type 2 diabetes (which is by far the most important metabolic disease).

He concluded that the results of several epidemiological studies suggest that daily consumption of 5 to 6 cups of green tea can provide pronounced cardiovascular and metabolic benefits. Similar benefits can also be obtained via supplementation, however, and the results of several human clinical trials indicate that daily consumption of a green tea extract containing 200 to 300 mg of EGCG can accomplish this.

The other part of the challenge mentioned above deals with other medical conditions. In the author’s own words (references omitted),5

A large part of the research on green tea has focused on its effects related to the prevention of cancer, and encouraging knowledge regarding efficacy, safety, and potential mechanisms of action has accumulated in this area. Furthermore, the anti-inflammatory, anti-arthritic, anti-bacterial, anti-angiogenic, anti-oxidative, anti-viral, and neuroprotective effects of green tea and isolated green tea constituents have been investigated. Recently, many of the aforementioned beneficial effects of green tea were attributed to its most abundant catechin, EGCG.

Regarding green tea’s anticancer properties, see “Green Tea Boosts Cancer Defense” in the October 2007 issue.

Drink (and Supplement) Up!

Especially when used in conjunction with an EGCG-rich green tea supplement, Pu-erh tea can help people lose weight and reduce their risk for cancer. It can also help them keep their cholesterol levels under control, thanks mainly to the green tea’s EGCG and other catechins. Lower cholesterol levels mean a reduced risk for atherosclerosis and heart disease.

Whether the tiny amount of lovastatin in Pu-erh tea actually helps appreciably in this regard is not known, but it’s intriguing to think that scientists may find ways to increase that amount substantially in the coming years. Meanwhile, it’s nice to know that every time you sip a cup of Pu-erh tea, you’re giving your body a couple of nature’s genuine treasures—the lovastatin and the tea itself.

References

  1. Hwang LS, Lin LC, Chen NT, Liuchang HC, Shiao MS. Hypolipidemic effect and antiatherogenic potential of Pu-erh tea. In Oriental Foods and Herbs: Chemistry and Health Benefits. ACS Symposium Series 859, pp 87-103. American Chemical Society, Washington, DC, 2003.
  2. Yang DJ, Hwang LS. Study on the conversion of three natural statins from lactone forms to their corresponding hydroxy acid forms and their determination in Pu-Erh tea. J Chromatogr A 2006;1119:277-84.
  3. Jeng KC, Chen CS, Fang YP, Hou RCW, Chen YS. Effect of microbial fermentation on content of statin, GABA, and polyphenols in Pu-Erh tea. J Agric Food Chem 2007;55:8787-92.
  4. Abdou AM, Higashiguchi S, Horie K, Kim M, Hatta H, Yokogoshi H. Relaxation and immunity enhancement effects of γ-aminobutyric acid (GABA) administration in humans. BioFactors 2006;26:201-8.
  5. Wolfram S. Effects of green tea and EGCG on cardiovascular and metabolic health. J Am Coll Nutr 2007;26:373S-88S.


Will Block is the publisher and editorial director of Life Enhancement magazine.

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