How our diet affects our health is a very complicated topic. For example, while drinking tea is thought to possibly help reduce the risk of a number of diseases and health conditions, many studies have had inconsistent results, and the chemical mechanisms that go on in our bodies are not well understood. However, a recently published study has helped us better understand how drinking green tea — both as a one-time event and as a habit — may lower DNA damage in a person. (Preventing DNA from getting damaged, and fixing damaged DNA, is important for keeping a person’s cells, and their entire body by extension, in a healthy condition.)
The researchers found that after a person drinks green tea, DNA damage in their cells decreased, which has obvious implications for people wanting to eat certain foods to stay healthy. At the same time, an enzyme that’s involved in the DNA-repairing process became much more active. It definitely looks like a promising correlation to explore.
Specifically, the researchers had people drink a cup of green tea either one time only, or twice a day for 7 days in a row. (Drinking just water was used as a control.) At 60 and 120 minutes after people drank the tea (either once or habitually), blood samples were taken and it was found that the amount of DNA damage in the blood’s cells (specifically lymphocytes) was about 30% lower. The activity of an enzyme called human oxoguanine glycosylase 1 (also known as 8-Oxoguanine glycosylase, or hOGG1), which is known to be involved in DNA repair, was also significantly higher at these times.
The authors suspect that this correlation shows that a larger DNA repair process is triggered due to consuming green tea, but it’s still unknown how this happens on a molecular basis — why does green tea affect the body this way? (And it’s important to keep in mind that the researchers have so far shown correlation but not causation.)
It’s possible that catechins are involved, but much more work will need to be done to know either way. Catechins are polyphenols, which are chemicals that are abundant in tea leaves and are known to cause many of the properties we enjoy in tea. Most of the polyphenols in tea leaves (about three-fourths of them) are catechins, which is a more specific subgroup of polyphenols. Many different catechins are in tea leaves, and these chemicals give green tea its characteristic bitter and astringent taste.
So while it’s hard to isolate the effects of specific dietary factors — like regularly drinking tea — on a person’s health, studies like this one do help to elucidate it a bit at a time.
For much more on the biochemistry of teas, check out Teisha J. Rowland’s book Biology Bytes: Digestible Essays on Stem Cells and Modern Medicine.
For further reading:
- Cyrus K. Ho, Siu-wai Choi, Parco M. Siu, and Iris F. F. Benzie’s article “Effects of single dose and regular intake of green tea (Camellia sinensis) on DNA damage, DNA repair, and heme oxygenase-1 expression in a randomized controlled human supplementation study”
- Rina Shaikh-Lesko’s article “Beneficial Brew”
- Teisha J. Rowland’s book Biology Bytes: Digestible Essays on Stem Cells and Modern Medicine