Green Tea And Toxins/Mycotoxins

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What Is Green Tea - Camellia sinensis

Green tea is made by drying fresh leaves (roasting) at high temperatures to inactivate the oxidizing enzymes. It is a non-fermented product that contains several tea polyphenols that have been thorougly studied. These polyphenols are largely Green tea catechins (GTCs), that comprise 30–40% of the extractable matter from dried green tea leaves. Tea catechins include epigallocatechingallate (EGCG), epicatechingallate (ECG), epicatechin (EC), and epigallocatechin (EGC). Epigallocatechingallate is the most abundant ,and most bioactive constituent. These polyphenols are known to function as antioxidants to scavenge reactive oxygen species (ROS) such as superoxide, hydrogen peroxide (H2O2), and hydroxyl radicals. Green tea catechins have demonstrated the ability to quench free radicals generated by oxidative environmental toxicants , thereby reducing toxicant-mediated cell damage, mutation-mediated DNA damage, cancer, and cell death.

Metabolic Fate Of Green Tea

GTCs are metabolized in the body through biotransformation pathways predominantly in the liver and intestine. They include methylation, glucuronidation, sulfation, oxidative degradation, and ring-fission metabolism. After exiting the liver, GTCs and their metabolites are released into circulation system and distributed to different organs and tissues. Although GTCs have many metabolites in the human body, the biological activity of those metabolites remains unknown. It is my belief (unproven but some science to back it up) that polyphenols such as these catechins are delivered to inflammatory tissue in their conjugated states where they are unconjugated to perform their antioxidative duties)

Green Tea Has Been Shown To Be Protective Against EnvironmentalToxins That Cause Oxidative Stress

  • Pesticides
    • Rotenone
    • Paraquat
    • DDT
  • Cigarette smoke toxins
  • Mycotoxins

Green Tea polyphenols protective against aflatoxin B1

A study showed Green tea polyphenosl will reduce the aflotoxin level by 15% in three months when taking 500 mg BID. Equivalent to two cups of strong green tea.

 

Green Tea May However Contain Mycotoxins

Several studies were reviewed for an idea of how much aflatoxin and ochratoxin was commonly in Green tea on the market. Green tea is largely from China and India where heavy metals, pesticides and mycotoxins are more often found on foods.

The processing of Green tea gives it less time to be contaminated than other tea processing methods. Fresh leaves are immediately steamed or pan cooked to deactivate oxidizing enzymes and retain polyphenols. Steaming is followed by rolling and drying.

Aspergillus, Penicillium, Rhizopus, Eurotium, Cladosporium, and Trichoderma genera species were identified in tea.

Some Green teas, such as the Pu-erh teas need many years of maturation to be considered ripened and these teas are more contaminated.

The authors of the studies said most contaminants leached into the tea brew, including mycotoxins were not detected, or were found at a level lower than the regulatory limits and did not pose a public health hazard.

By the way, black tea had high levels of mycotoxins. Pu-erh tea had more than any other kinds of teas due to the processing methods. Regular raw Green tea had the least amount of mycotoxin contamination.

 

Research Articles

Carcinogenesis. 2008 Feb;29(2):411-7. doi: 10.1093/carcin/bgn008. Epub 2008 Jan 12.
Modulation of aflatoxin biomarkers in human blood and urine by green tea polyphenols intervention.
Tang L1, Tang M, Xu L, Luo H, Huang T, Yu J, Zhang L, Gao W, Cox SB, Wang JS.
PMID: 18192689 [PubMed - indexed for MEDLINE] Free full text

My review of this article: There is an association between hepatitis B, aflatoxin B1 exposure and hepatocellular carcinoma. Both hepatitis B and aflatoxin B1 exposure are known to cause hepatocellular carcinoma and both of them together act synergistically unfortunately. This is one of the most common cancers in SE Asia and W. Africa. Green tea polyphenols(GTP) have been found to inhibit a variety of carcinogenic tumors, including aflatoxin induced liver tumors. Several studies observed that GTPs modulated AFB1 metabolism, inhibited AFB1 DNA binding and AFB1-induced glutathione S-transferase (GST)-positive hepatocytes (Qin G, et al. 1997)

aflatoxins are primarily produced by Aspergilus flavus and Aspergilus parasiticus and are contaminants in the food supply. Aflatoxin B1(AFB1) is hepatotoxic and genotoxic and a known human carcinogen. Chronic expospure to low levels is known to be a risk for HCC. Vaccination for hepatitis B and food safety controls are being attempted but in the mean time researchers are looking for another method to prevent HCC. Ingestion of GTP on a daily basis is a method they are examining.

This research examined the use of green tea polyphenols in human subjects by looking at aflatoxin biomarkers in individuals at high risk of hepatocullular carcinoma(HCC). The same researchers looked at aflatoxin damage by examining the biomarkers of oxidative DNA damage in a prior experiment undertaken for 3 months and found green tea polyphenols reduced these biomarkers. This research was undertaken to further evaluate the aflatoxin biomarkers in the serum and urine samples of the subjects.

116 subjects completed the 3 months trial. They all had detectable aflatoxin marker in their serum. All three treatment groups had similar levels at the start of the trial. The placebo group never changed. The group given 500 mgs per day of green tea polyphenols had a significant decrease and the group given 1000mg had a marginally significant decrease.

The subjects urine samples had similar amounts of aflatoxin marker in them at the beginning of the study. The placebo group did not change while the 500mg polyphenol group had a reduction of 42% and the 1000mg plyphenol group had a reduction of 43%. at 3 months.

 

Inhibitory effects of tea extract on aflatoxin production by Aspergillus flavus.
Mo HZ, Zhang H, Wu QH, Hu LB.
Lett Appl Microbiol. 2013 Jun;56(6):462-6. doi: 10.1111/lam.12073. Epub 2013 Apr 22.
PMID: 23573983 [PubMed - indexed for MEDLINE]

 

Modulation of aflatoxin biomarkers in human blood and urine by green tea polyphenols intervention.
Tang L, Tang M, Xu L, Luo H, Huang T, Yu J, Zhang L, Gao W, Cox SB, Wang JS.
Carcinogenesis. 2008 Feb;29(2):411-7. doi: 10.1093/carcin/bgn008. Epub 2008 Jan 12.
PMID: 18192689 [PubMed - indexed for MEDLINE] Free Article

 

A comparative study on the antimutagenic properties of aqueous extracts of Aspalathus linearis (rooibos), different Cyclopia spp. (honeybush) and Camellia sinensis teas.
van der Merwe JD, Joubert E, Richards ES, Manley M, Snijman PW, Marnewick JL, Gelderblom WC.
Mutat Res. 2006 Dec 10;611(1-2):42-53. Epub 2006 Sep 1.
PMID: 16949333
[PubMed - indexed for MEDLINE]

 

Inhibition of eleven mutagens by various tea extracts, (-)epigallocatechin-3-gallate, gallic acid and caffeine.
Hour TC, Liang YC, Chu IS, Lin JK.
Food Chem Toxicol. 1999 Jun;37(6):569-79.
PMID: 10478825 [PubMed - indexed for MEDLINE]

 

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