Green Tea

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Latest Edit: Hector 2014-3-17 (EDT)

See Also Food Supplements

Green tea is made from the tea plant, Camellia sinensis, the same plant form which black tea is derived. Green tea is produced by lightly steaming fresh cut leaves. This process prevents oxidation which occurs in black tea production - a proccess that inactivates compounds known as polyphenols that are consequently found in higher concentrations in green tea [1] The polyphenolic flavonoids present in green tea of interest are:

  • Catechin
  • Epicatechin (EC)
  • Epicatechin gallate (ECG)
  • Epigallocatechin gallate (EGCG)
  • Proanthocyanidins [2]

A typical cup of green tea contains 50 to 100mg of polyhpenols, with EGCG having the highest concentration.[1]

Other compounds found in green tea include Caffeine, Theanine and Lignin. Due to green teas high concentration of polyphenols and corresponding antioxidant properties, it has been investigated in cancer treatment and prevention[1].

Contents

Food Sources

Green tea is traditionally steeped in hot water and consumed as a tea, but is also available in supplement form.

Uses

The following is a list of the primary uses for Green Tea.

  • Intestinal Dysbiosis and Infection. Studies have demonstrated green tea has antimicrobial properties against many types of gram-negative and gram-positive bacteria that cause common diseases such as cystitis, pyelonephritis, diarrhea, dental caries, pneumonia, and skin infections. A small Japanese study assessed the effects of green tea supplementation (in the form of EGCg) on intestinal dybiosis and found that EGCg raised levels of Lactobacili and Bifidobacteria and lowered levels of several strains of pathogenic bacteria.[2]

Liver Conditions

Oral Cavity Diseases

  • The use of green tea rinses and chews has been shown to decrease levels of gum inflammation. High levels of catechins and gallates are found in the oral cavity after use of tea leaves and are thought to be responsible for this anti-inflammatory and antimicrobial action. Studies recommend green tea as a adjunct in the treatment of gum disease and in routine dental care.[1]

Obesity and Weight Loss

  • A small double blind placebo controlled study of middle aged obese women showed that supplementation with a green tea supplement with a 1800 calorie/day diet three times the weightloss when compared with a 1800 calorie/day diet alone. At four week women in the placebo group had lost an average of 1kg while the supplementation group had lost an average of 2.9kg. Waist size and blood triglycleride levels were also improved to a greater extent in the supplementation group. [4]

Acne Vulgaris

  • Green tea has been shown to inhibit type 1 alpha reductase enzyme, which in turn decreases the detrimental affects androgens have on the skin. There is little clinical study regarding green tea supplementation in the treatment of acne, and much more research is needed [5]

Multiple Sclerosis (MS)

  • The antioxidant activity of green tea had made it a candidate for therapeutic treatment in MS, as MS is characterized by increased oxidative stress. Although there are currently no studies involving human MS patients and green tea, animal models have shown that EGCG reduces brain inflammation and neuronal damage, and prevents neurotoxic reactive oxygen species formation.[5]

Prescribing Considerations

  • The recommended dosages varies based on age and health status. Typical dosage recommendations are between 3 and 10 cups per day. Cancer preventative doses are at the higher end of this range.
  • Green tea extracts are standardized to polyphenol content and average dosage is between 500-1500mg per day (the equivalent of 5 to 15 cups).[2]

Safety

Green tea is considered safe and non-toxic when consumed regularly. It is important to note that a cup of green tea generally contains between 10-50mg of caffeine and over consumption of caffeine may cause irritability, insomnia, nervousness, and tachycardia.

  • Children - Green tea and green tea extracts should not be ingested by infants as doses above 250ml/day may affect iron metabolism and cause microcytic anemia.[3]
  • Contraindications:
  • End Stage Renal Disease - Due to its high potassium content patients with end stage renal disease should avoid consumption of green tea. [3].
  • Drug Interactions
  • No reported drug interactions. Although there are theoretical concerns due to caffeine's antiplatelet activity when co-administered with anticoagulants.[1]
  • Nutrient Interactions
  • None reported.

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Pizzorno Joseph E, Murray Michael T (1999) Textbook of Natural Medicine, Elsevier.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Green Tea Monograph. Alt Med Rev 2000 (5)2: 372-75
  3. 3.0 3.1 3.2 3.3 McKenna DJ et al. (2000) Green tea monograph. Alternative Ther Health Med;6(3):61-84.
  4. Lecomte, A (1985) Clinical study of weight loss using Arkogelules green tea. Revue de l'Association Mondiale de Phytotberapie(1): 36-40
  5. 5.0 5.1 Prousky Jonathan (2008) Principles and Practices of Naturopathic Clinical Nutrition CCNM Press.
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