Catechin

Catechin: How it works?

• Green tea extract contains catechins (CA), which are polyphenolic compounds, the major being epicatechin, epigallocatechin, epicatechin-3-gallate, and epigallocatechin-3-gallate.

• These fall within the family of flavonoids, and are thought to have antioxidative potential, but these studies have often only been demonstrated in vitro studies.

• It is also proposed that catechins upregulate lipid-metabolizing enzymes via the NF-κB activation by inhibiting the peroxisome proliferator-activated receptors (PPARs) that are important transcription factors for lipid metabolism, and in theory mRNA expression of lipid-metabolizing enzymes would be upregulated.

What is it used for?

• Catechin is a frequent ingredient in herbal and dietary supplements, typically labeled as green tea extract.

• It is typically marketed as an antioxidant and a weight loss supplement.

Evidence for or against its use:

• The European food safety authority had a safety meeting regarding the safety of consuming green tea catechins.

• The conclusion was that green tea infusions, prepared in a traditional way, are in general safe for consumption; however, there is evidence from interventional clinical trials that doses equal or above 800 mg a day can induce a statistically significant increase of serum transaminases.

• One study evaluated the influence of green tea catechin beverage on body composition and fat distribution in overweight and obese adults during exercised-induced weight loss.

• 107 participants were assigned to receive a beverage containing ~625 mg of catechins with 39 mg of caffeine or a control beverage for 12 weeks and participate in similar amounts of moderate intensity exercise.

• Percentage changes in fat mass did not differ between the catechin group compared to the control group, but percentage changes in total abdominal fat area and fasting serum triglycerides were greater in the catechin group.

• These findings suggest that the consumption of a beverage containing green tea catechins (625 mg/day) may enhance exercise-induced loss of abdominal fat and improve circulating free fatty acids and triglyceride levels.

• However, a meta-analysis of six studies on 532 participants produced a very small, statistically non-significant mean difference in weight loss.

Safety concerns, side effects, and precautions:

• Catechins were implicated in several case reports regarding hepatoxicity.

• A further investigative report assayed herbal dietary supplements that were implicated in human hepatotoxicity and screened for catechins.

• The results were that many of these supplements may commonly contain catechins even if their presence is not listed on the drug label, but there was no statistically significant association between presence of catechin or the dose consumed in liver or causality score, severity, or pattern of liver injury.

• Additionally, the US Pharmacopeia conducted a systematic review to determine the safety of green tea extracts with the conclusion that these extracts can contain hepatotoxic solvent residues, pesticide residues, pyrrolizidine alkaloids, and elemental impurities, but no evidence of involvement in actual green tea extract induced injury.

• Therefore, the official conclusion from this review was to include a cautionary label that recommends not to use if patients have any pre-existing liver problem.

  
  

Key Sources

• Moraru C, Mincea MM, Frandes M, Timar B, Ostafe V. A meta-analysis on randomised

  controlled clinical trials evaluating the effect of the dietary supplement chitosan on weight

  loss, lipid parameters and blood pressure. Medicina. 2018;54(6):109. https://doi.org/10.3390/

  medicina54060109.

• Koide SS. Chitin-chitosan: properties, benefits and risks. Nutr Res. 1998;18(6):1091–101.,

  ISSN 0271-5317. https://doi.org/10.1016/S0271-5317(98)00091-8.

• Walsh AM, Sweeney T, Bahar B, O’Doherty JV. Multi-functional roles of chitosan as a poten-

  tial protective agent against obesity. PLoS One. 2013;8(1):e53828. https://doi.org/10.1371/

  journal.pone.0053828.

• Huang H, Liao D, Zou Y, Chi H. The effects of chitosan supplementation on body weight

  and body composition: a systematic review and meta-analysis of randomized controlled trials. Crit Rev Food Sci Nutr. 2020;60(11):1815–25. https://doi.org/10.1080/10408398.201

  9.1602822.

• Huang SS, Sung SH, Chiang CE. Chitosan potentiation of warfarin effect. Ann Pharmacother.

  2007;41(11):1912–4. https://doi.org/10.1345/aph.1K173. Epub 2007 Oct 9.

• Miller K. Chitosan uses and risks. 5 Feb 2021. https://www.webmd.com/vitamins-and-sup-

  plements/chitosan-uses-and-risks. Accessed 1 May 2022.