Sunburn is a classic summer problem. Who has never looked like a crayfish after forgetting to put on sunscreen? Tea leaves have been scrutinized for their formidable antioxidants that would be able to limit or even prevent sun damage. To what extent? Under what conditions?
Sunburn: UV rays.
The sun's rays are electromagnetic rays that are composed of "spectra" (red, blue, etc.). Among these, there are waves not visible to the naked eye called ultraviolet waves or UV. Sunburn is a burn of the skin due to too much exposure to the sun (this is also the case for tanning booths!). Depending on the amount of sunshine, the thickness of the ozone, the level of melanin, the altitude, etc., you are more or less exposed to these waves. The main danger of these waves is that UV can induce damage to the DNA of cells, which can result in inflammation, cell death or the generation of mutations. The stronger and more frequent this phenomenon is, the greater the risks (skin aging, skin damage, cancer, etc.).
Faced with climate change, but also with our lifestyle, researchers are interested in reducing the risk of skin damage by the sun through tea. The antioxidant properties of polyphenols, particularly the catechins in green tea, appear to be interesting for reducing damage. But in practice, how does it work?
Tea cream
One of the most quoted publications published in 2001 was interested in the effects of green tea extracts (0.25% to 10% of extracts in the formulation) applied on the skin of some volunteers. The aim: to show the prevention of sunburn by green tea extracts. After non-intense exposure of the skin to UV radiation, the authors found that the increasing dose of extracts used (with good results from 2.5%, with a maximum at 5%) was able to reduce the formation of local inflammation by 66% and to reduce the formation of DNA damage. These first results on prevention are interesting but the pool of 6 volunteers, the brief and artificial exposure (only one type of UV) require further investigations.
20 years later, several studies have provided more answers. Saric and Sivamani summarized about 15 publications on green tea and humans subjected to sunburn. Interestingly, green tea extracts seem to have an effect when they are concentrated to a minimum of 2 to 3% as shown by Elmets in 2001. The decrease in the proportion of burnt cells is at least 38.9%. A decrease in the number of inflammatory cells in the skin is also observed, indicating that tea extracts would prevent local inflammation.
Tea pill
Tea drinkers do not usually pour the contents of their teapot onto the skin, but rather enjoy their delicious brew. There is a lot of data on tea consumption and prevention of UV damage. If I quickly summarize some studies, it seems that ingesting tea extracts prevents UV damage from the sun's rays. How does it work? Skin analyses conducted by Clarke et al. have shown that the presence of polyphenols in sufficient quantity to be responsible for a protection. Far from being total, it would represent an additional protection with the sun creams.
A fundamental element to these studies is very important to note for us tea drinkers: all these results come from encapsulated tea extracts.
Why encapsulated tea extracts? During the journey of our delicious liquor, our digestive system will eliminate half of the polyphenols, so we need to protect them. In order to have an effect, some research shows that the polyphenols contained in tea extracts can reach more than 1000mg, which would represent an average of 5 cups of 20 cl of tea per day. In reality, to reach more than 1000mg of polyphenols, we would have to double our tea consumption, which means 10 cups of tea per day. I let you imagine how you would feel with all the caffeine ingested! So you should not believe that drinking tea will protect you from sunburn ... unless you want to have problems with caffeine or anemia!
Thus, tea extracts and in particular green tea extracts would appear to be interesting as a supplement in creams intended for the prevention of sunburn but at a fairly high concentration, at least 2 to 3%. In addition, the consumption of encapsulated green tea extracts could reinforce the protection offered by sun creams. However, this concentration should be high (more than 1000 mg), which does not allow to have this effect with our tea consumption (at least 10 cups of 20 cl per day would be necessary. 40g of tea in classic infusion, hello caffeine and risk of anemia).
Guerra et Crane 2022 https://pubmed.ncbi.nlm.nih.gov/30521258/
Elmets et al. 2001 https://pubmed.ncbi.nlm.nih.gov/11209110/
Saric et Sivamani 2016 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5037798/
Clarke et al. 2016 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4694608/
Kapoor et al. 2021 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8233826/