The effects of green tea on acne vulgaris: A systematic review and meta‐analysis of randomized clinical trials

Abstract

Green tea extract (GTE) has been studied for the treatment of acne based on its anti‐inflammatory/antioxidant properties. This systematic review and meta‐analysis aimed to examine the effects of GTE on acne. Electronic databases, including PubMed, Embase, and the Cochrane Library were systematically searched up to August 2019. The effect size of acne lesion counts is presented as mean differences and 95% confidence intervals (CIs). Five randomized‐controlled studies were included in the meta‐analysis (N; experimental = 125, control = 122). GTE significantly reduced the number of inflammatory lesions (−9.38; 95% CI: −14.13 to −4.63). In subgroup analysis, topical GTE application significantly reduced the inflammatory lesion counts (−11.39; 95% CI: −15.91 to −6.86) whereas oral GTE intake showed minimal effect (−1.40; 95% CI: −2.50 to −0.30). Although GTE did not significantly reduce the number of non‐inflammatory lesions (−21.65; 95% CI: −47.52 to 4.22), when stratified by the route of admission, non‐inflammatory acne lesions were significantly reduced by topical GTE application (−32.44; 95% CI: −39.27 to −25.62) but not with oral GTE administration (0.20; 95% CI: 0.00 to 0.40). This systematic review and meta‐analysis suggest that topical GTE application is beneficial for the treatment of acne without causing significant adverse events while oral GTE intake has limited effects. Further high‐quality clinical trials are warranted.

Green and white teas as health-promoting foods

“…The latest research reported that the consecutive consumption of 700 ml of high EGCG green tea for one month could alleviate symptoms such as runny nose, itching eyes and watering eyes in people with Japanese cedar pollinosis. 84 In a mouse model with allergic rhinitis, oral administration of EGCG decreased the occurrence of nasal rubbing and the number of sneezes. The level of immunoglobulin E, histamine and proinflammatory cytokines was also lower in the EGCG-treated mice.…”

“…The level of immunoglobulin E, histamine and proinflammatory cytokines was also lower in the EGCG-treated mice. 84…”

“…114 Gut microbiota can regulate the immune system, prevent chronic diseases and affect the metabolism and bioavailability of different compounds. 84,113,114 Meta-analytical methods showed that the consumption of tea, specifically black tea, 114 oolong tea 115 and green tea 116 affected the abundance of gut microbiota in a dose-dependent manner. 116 Green tea polyphenols can modulate the diversity and composition of the gut microbiota.…”

“…84,86,97,[113][114][115][116][117][118][119][120][121][122][123] Studies suggest that they promote the growth of specific bacteria, mainly beneficial bacterial species such as Bifidobacterium spp., Lactobacillus spp., Clostridium coccoides, Actinobacteria and Firmicutes, while inhibiting the proliferation of pathogenic bacterial species such as Clostridium perfringens, Clostridium difficile, Bacteroides spp., E. coli O157 and Helicobacter pylori. 84,114,115,117,124 These changes in turn affect the host health. The antibacterial activity can be explained the binding of polyphenols to bacterial membrane proteins, and their pro-oxidant effect (which will alter the permeability) and the possible inhibition of glucose transport 84,117 and changes in the metabolic profile of bile acids.…”

“…84,114,115,117,124 These changes in turn affect the host health. The antibacterial activity can be explained the binding of polyphenols to bacterial membrane proteins, and their pro-oxidant effect (which will alter the permeability) and the possible inhibition of glucose transport 84,117 and changes in the metabolic profile of bile acids. 97 On the contrary, the increase in beneficial bacteria could be related with the prebiotic effects of tea phenolic compounds.…”