Tea - NutraPedia

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Tea: An Overview of Health Implications

1) Conditions Studied

Tea, particularly green tea, has been studied for a variety of health conditions, including but not limited to cardiovascular diseases, certain cancers, obesity, diabetes, neurodegenerative disorders, and as an agent for general health maintenance and longevity.

2) Efficacy in Treating Conditions

While research suggests some positive correlations, the efficacy of tea in treating specific conditions is not conclusively established. For example, some studies have found that tea may help lower the risk of heart disease and certain types of cancer, and improve weight loss efforts. However, these findings are not universally agreed upon, and more research is needed to determine the effectiveness of tea as a treatment for these conditions.

3) Health Benefits

  • Antioxidant Properties: Tea is rich in antioxidants known as polyphenols, which can help protect against oxidative stress and inflammation.
  • Heart Health: Regular consumption of tea may be associated with a reduced risk of heart disease and stroke.
  • Weight Management: Some studies suggest that tea can aid in weight loss and help combat obesity.
  • Mental Alertness: The caffeine content in tea can improve brain function and increase alertness and focus.
  • Hydration: Herbal teas can contribute to daily hydration needs.

4) Downsides

  • Caffeine Content: Tea contains caffeine, which can cause insomnia, anxiety, irritability, and stomach upset in sensitive individuals.
  • Iron Absorption: Certain compounds in tea may interfere with the absorption of iron from food.
  • Contaminants: Some teas may be contaminated with heavy metals or pesticides if not properly sourced or produced.

5) Genetic Variations

There is emerging research suggesting that genetic variations may affect how individuals metabolize components in tea, such as caffeine. For example, certain polymorphisms in the CYP1A2 gene can influence caffeine metabolism, potentially making tea more beneficial or harmful depending on the individual's genetic makeup. However, more research is needed to fully understand these interactions and to provide personalized dietary recommendations.

Tea Research Summary

Aged and Ripened Pu-erh Tea Analysis

A study using high-performance liquid chromatography and mass spectrometry found that aged pu-erh tea and ripened pu-erh tea have different levels of catechins and gallic acid, with ripened pu-erh tea having more gallic acid and caffeine.

Impact of Milk on Tea's Cardiovascular Benefits

Research involving healthy volunteers revealed that milk negates the vascular function benefits of black tea by blocking the effects of tea catechins, possibly due to the formation of complexes with milk caseins.

Tea Leaf Extracts and Thromboxane Levels

A compound from unprocessed tea leaves significantly reduced thromboxane levels and cholesterol in rats, suggesting health benefits that are diminished in processed tea.

Microbial Fermentation and Bioactive Components in Pu-Erh Tea

Fermentation with specific microorganisms can increase the content of statin, GABA, and polyphenols in Pu-Erh tea, thereby enhancing its potential health benefits.

Decaffeination and Volatile Compounds in Green Teas

A study found that decaffeination reduces the volatile components responsible for green tea's aroma, particularly terpene-type compounds.

Milk, Tea Catechins, and Bioaccessibility

Adding milk to tea reduces total catechin content but does not significantly affect the bioaccessibility of catechins after digestion.

Conversion of Lactone Form Statins in Pu-Erh Tea

Research showed that alkaline solutions with acetonitrile or methanol could effectively convert lactone statins, with implications for analyzing statins in Pu-Erh tea.

Chemical Makeup of UK Teas

Teas in the UK show wide variability in phenol, catechin, and caffeine content, influenced by factors like agricultural conditions and fermentation degree.

Flavonoid-Protein Interactions and Antioxidant Capacity

The antioxidant capacity of flavonoids in tea can be 'masked' by their interaction with proteins such as caseins and albumin.

Proteins and Catechin Bioavailability from Green Tea

Dietary proteins reduce the bioavailability of certain catechins from green tea, though non-galloylated catechins increase in bioavailability when proteins are added.

Inhibitory Effect of Green Tea Compound on Thromboxane

A substance in dry green tea leaves named L2 significantly inhibits thromboxane formation, suggesting potential for treating vascular diseases.

Antioxidant Properties and NO Scavenging in Fermented Tea

The fermentation of tea affects its antioxidant properties and nitric oxide scavenging abilities, with post-fermented pu-erh tea showing effectiveness in inhibiting NO production.

ACE Inhibition by Tea Polyphenols

Polyphenols from different types of tea inhibit Angiotensin Converting Enzyme (ACE) with varying effectiveness, potentially aiding in blood pressure regulation.

Theabrownin Formation in Pu-Erh Tea Fermentation

Exogenous enzymes during Pu-Erh tea fermentation increase theabrownin levels and affect tea polyphenol content, impacting the tea's quality.

Catechin Absorption in Green and Black Tea

Both green and black teas rapidly increase blood catechin levels, with their bioavailability unaffected by the addition of milk.

Chemical Profiles of White and Green Teas

White teas have variable catechin levels and generally lower antioxidant capacity than green teas, emphasizing the need for specifying tea subtype and processing in health-related claims.

GABA Content in Pu-Erh Tea

Pu-erh tea has lower GABA levels than other Chinese teas, with the content decreasing during fermentation, challenging the notion that GABA is a major bioactive component in pu-erh tea.


  1. Comparison of the chemical constituents of aged pu-erh tea, ripened pu-erh tea, and other teas using HPLC-DAD-ESI-MSn
  2. Addition of milk prevents vascular protective effects of tea
  3. A potent thromboxane formation inhibitor in green tea leaves
  4. Effect of microbial fermentation on content of statin, GABA, and polyphenols in Pu-Erh tea
  5. Effect of supercritical carbon dioxide decaffeination on volatile components of green teas
  6. Effect of milk and brewing method on black tea catechin bioaccessibility
  7. Study on the conversion of three natural statins from lactone forms to their corresponding hydroxy acid forms and their determination in Pu-Erh tea
  8. Total phenol, catechin, and caffeine contents of teas commonly consumed in the United kingdom
  9. Interactions between flavonoids and proteins: effect on the total antioxidant capacity
  10. Simultaneous ingestion of dietary proteins reduces the bioavailability of galloylated catechins from green tea in humans
  11. A potent inhibitor of thrombin stimulated platelet thromboxane formation from unprocessed tea
  12. Variations of antioxidant properties and NO scavenging abilities during fermentation of tea
  13. 2-Amino-5-(N-ethylcarboxamido)-pentanoic Acid from Green Tea Leaves
  14. Inhibition of angiotensin converting enzyme (ACE) activity by polyphenols from tea (Camellia sinensis) and links to processing method
  15. Effects of enzymatic action on the formation of theabrownin during solid state fermentation of Pu-erh tea
  16. Bioavailability of catechins from tea: the effect of milk
  17. White and green teas (Camellia sinensis var. sinensis): variation in phenolic, methylxanthine, and antioxidant profiles
  18. Determination and comparison of γ-aminobutyric acid (GABA) content in pu-erh and other types of Chinese tea

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