Defending Against Cancer
Vegetables deliver a great array of salutary substances, such as various flavanoids, vitamins and minerals that are vital to basic health
Know Your Grocery
The substances in plant produce that account for the health benefits are sometimes called phytochemicals. One system that employs phytochemicals most extensively is Traditional Chinese Medicine (TCM). However, some regular grocery items can be surprisingly full of them: grapes, strawberries, olives, watercress, coriander, or even onions and soy beans are some common providers. Dr George Ku, who has previously worked as a pharmaceutical developer for over 20 years in the US and the holder of a long list of patents, and who has in recent years become an advocate for natural therapies, pinpoints three types of food products which cancer preventive phytochemicals can be effectively obtained in the diet (11):
- Cruciferous vegetables such as bok choi, cabbage, broccoli etc for the phytochemical indole-3-carbinol
- Turmeric, the intensely yellow ginger used in curry powder, for curcumin
- Green tea for tea catechins, in particular epigallocatechin-3-gallate —EGCG
There are actually a few substances from different categories of tea that can be contributive to cancer prevention (12), but since tea and its constituents are naturally existing materials which pharmaceutical companies cannot claim patents of, not a lot of resources have been put into more researches for better understanding and usage of them. A video of interest in the popular TED Talk program, Dr William Li of the Angiogenesis Foundation presents the fact that even the most effect drugs for cancer compare only marginally with substances in our normal grocers (13).
We present in this article here whatever is found by the science community, and hope more enlightening studies will come by. Most of the cancer and tea studies now focus in catechins and some touch on theaflavins, a group of flavonoids transformed from catechins.
Substances in Tea
EGCG — epigallocatechin 3-gallate — one of green tea’s catechins, is a most powerful antioxidant
Tea catechins are the majority of substances inside the fresh tealeaves, besides, of course, water and cellular structural materials (which some scholars refer to as ashes). They can be 15 to 30% of the dried weight of the leaf. Of all the catechins, EGCG, a somewhat bitter and white (colourless when dissolved in water) material, is most studied for its outstanding anti-carcinogenic potential.
Catechins exist in almost all categories of tea when they are freshly produced. Green and white teas hold the most of them. Some quantity of the catechins is transformed into other substances during production processing for oolongs, more so in black and dark teas. Some of these transformed substances are also of unique health nature, some are also taste and aroma materials. Examples of health interests are gallic acid, theaflavins, and some other forms of flavonoids.
It is also important to note that in addition to catechins and the above mentioned, other substances in tea such as theanine (a unique amino acid in tea), caffeine, vitamins, essential oils and minerals are also part of the package that delivers the synergic health effects of tea.
Catechins are fragile materials that can degenerate upon excessive contact with light, heat, humidity, oxygen and other foreign matters. Excessive processing, poor quality, and non-protective packaging result in the loss of catechins, and for that matter most substances in the tealeaves that contribute to tea’s health and taste qualities. The difference between a better quality whole leaf tea and a mass market product can be extremely dramatic. We have discussed that in various articles in this site and will not repeat here. Make your choice wisely.
Dear Leo,
Thank you very much for your prompt reply. Yes, as you correctly point out, I am aware that many responsible traders in the tea business check their pu’erh for pesticides and even the presence of heavy metals. However, very few do it for mycotoxins like aflatoxin. I only know of a couple of vendors based in Taiwan, and they only check the ripe pu’erh not the raw one.
However, the article that I mentioned from Yunnan Agricultural University claims that raw pu’erh is also strongly contaminated, which I personally find very alarming. I believe the authors of this study should be contacted by members of the tea industry to ask them for further clarification as their results are certainly disturbing, if true.
Concerning the incidence of liver cancer in Asia, and China in particular, and its connection to Hepatitis, I fully agree that the latter is the main cause. Therefore, it is utterly important to use vaccination to prevent infection and the possibility of developping hepatic cancer.
Nevertheless, it has been found by researchers that, once a person is infected by the Hepatitis B virus, the chances of developing liver cancer in the future become substantially higher (by a factor of 30) if he or she is exposed to aflatoxins. See, for instance:
https://www.ncbi.nlm.nih.gov/pubmed/11922091
Food stuff of frequent consumption in Asia like peanuts, corn, etc, are known to be often contaminated with mycotoxins, but I wonder if (wet/traditional stored) dark teas should be also blamed and therefore avoided, in case they turn out to be contaminated with high levels of mycotoxins.
Anyway, thanks for addressing my concerns in such a forthright manner. I look forward to your email in case you need me to provide you with a copy of the article from the Yunnan researchers. Please, do not hesitate to contact me.
Sincerely,
xiaobai
@xiaobai, thank you for this very meaningful discussion. Seems I will have to really spend time to do more research about this topic now. If you have not received the previous email we sent you about the two other reports, I shall have another sent to you right away.
The high rate of hepatitis in China, according to some other reports, relates more with the hygiene concept and food habits of the Mainlanders rather than the use of peanuts and corns. These staple food items are used popularly almost everywhere else. Furthermore, puer tea has never been really popular in the Mainland until the recent couple of decades since the spread of the teashop business trend and of course the speculation craze that has never really died down even now. Puer had only been popular in Hong Kong and neighbouring parts of Guangdong previously. Yet hepatitis and liver-related death in China has stayed high all the time throughout China. This seems to me a negative evidence of the argument that puer is part of the problem. However, the existence of the reports you cited are not to be dismissed. I shall most definitely write about the topic. Give me some time to do the needed study. Pls forward the copies you have. Thanks again.
Well, the address you have used to register in this site does not exist, according to the gmail response. You must have made a typo or something.
Dear Leo,
yes, sorry, there was a typo in the email address that I entered before. Please, try again.
I really apologize for the inconvenience.
By the way, I am not arguing about the causes for the high incidence of Hepatitis B in China. The latter is also an issue in other places like Taiwan and Malaysia (although this disease can be transmitted in absence of good hygiene, the main means of contagion are via contact with blood and other bodily fluids, e.g. sex). Of course, I am well aware of the lack of hygiene and manners of many mainlanders (I spend long periods in Taiwan, where we are also very familiar with this problem).
Anyway, please, contact me. I really think someone from the tea industry who is more qualified than me should contact the authors of those studies. Either they have made some big mistakes or there are serious reasons for concern
about pu-erh consumption.
No no no, I am not saying you are arguing. What I meant was the hypothesis. It is an expression that is very popular in academic discourse when there are discussions on different view points and presumptions of a hypothesis, an argument per se. I was only presenting why I think you should not be too worried. It is an issue that we tea people should look at anyhow. I’ll have an e-mail sent to you tomorrow for the documents. Thanks again in advance.
@xiaobai, thank you for the well thought out comment, and thank you for offering the copy of the reports. I shall contact you separately through email for it. Although we subscribe to a major distributor of science and technology reports, you probably understand that any such subscriptions would not include all things going on, in particular those from the sources that you have cited.
Mycotoxins are a concern for a number of food items that are produced through fermentation; and pu’er, either sheng or shu, are no exceptions. I have been keeping an eye on that for commercial purposes.
With the exception of Taiwan, this category of contaminants is not high in priority in the importers’ radar for tests, so far as I have been aware of. However, some other compounds are. For example, Anthraquinone. We have found it in two of our candidates for launching in Europe. On further investigation, we have found that it has been the cause for the rejection of a number of major shipments of pu’er entering Europe. We suspect it has been a major reason why not more importers are buying. I have been discussing with an European client on the situation and hope to find a way to combat the issue with Yunnan producers.
Anthraquinone comes not from fertilisers or insecticides. We are trying to find where it comes from. If what we suspect is true, the production processes of many other F&B items may have to change to avoid it, not only for China, but everywhere else.
I cannot talk further on that yet since this is all speculations right now.
As for higher liver cancer rates in populations of the Chinese descent, for many decades now there is an understanding in the medical profession that it is the wide spread of hepatitis rather than anything else. For example, 100% of Chinese adults in the Chinese Mainland have found to be hepatitis positive. Sometimes I wonder why the liver cancer rate in China ( not HK ) is not higher than the official figure. That is also why I have been extremely careful when travelling in China, especially when sharing the table with my Mainland friends.
As for the link between puer tea and that, I have yet to read convincing reports about it. I am looking forward to reading those quoted by you.
Dear Leo,
I was trying to post this question in the forum section of this website, but unfortunately, I could not find the find the link to register.
I was wondering if you have been following up on the recent research results
about mycotoxins (like, for instance aflatoxins) found in Puerh. Here are two examples of recent references from two different research groups in China:
https://www.tandfonline.com/doi/abs/10.1080/10942912.2014.885043#.VL9Toy6UcZM
https://www.lifescienceglobal.com/pms/index.php/jbas/article/view/2217
For the first article, only the abstract is freely accessible, but I will be glad to provide you with a copy if you contact me by email. I find the results disturbing,
although I think that the article may contain several typos, at least.
As a tea expert and a Hongkongnese with a long experience with puerh, I would love to hear your opinion on these recent research results, which, in my modest opinion, are a good reason for concern (e.g. you may be aware that aflatoxin
is a potent carcinogen, affecting especially the liver and that liver cancer is in the top 5 most common types of cancer in places like Hong Kong, Singapore, and Taiwan, with elevated consumption per capita of post-fermented puerh teas).
Best regards,
xiaobai