Green tea is an exceptional source of polyphenols, which can be up to one-third the weight of tea leaves (Camillia sinensis). Regular consumption of green tea is therefore an excellent way to absorb large quantities of these biologically active molecules, a single cup of green tea that can contain up to 200 mg of polyphenols, including epigallocatechin gallate (EGCG), the main molecule responsible for the beneficial effects of green tea on health.
A recent study of the genetic material of the tea plant indicates that this exceptional content of polyphenols is the result of important modifications in the genes of the plant as a result of its domestication a few thousand years ago1. Basically, the role of polyphenols is to protect the plant from multiple aggressions from its environment (microorganisms, insects, UV rays). By analyzing the entire genome of Camillia sinensis, a team of Chinese scientists has shown that the genes responsible for the production of these polyphenols have been “copied and pasted” multiple times during the recent evolution of the plant, This has greatly increased the levels of polyphenols in its leaves and has allowed it to adapt to different places where the plant is grown.
If this increase in polyphenol content is important for the tea tree, it is just as important for human health. Not only do polyphenols play an essential role in the organoleptic properties of tea because they give it its bitterness, but these molecules also have several biological activities that are very important for the prevention of chronic diseases.
One of the best-documented benefits of green tea consumption is on the prevention of several types of cancers, particularly those of the mouth, colon and prostate (metastatic form of the disease). This preventive effect is largely due to EGCG, with more than 11,000 scientific studies that have shown that this versatile molecule is able to interfere with a host of processes used by cancer cells to grow and invade organs.
The positive effect of EGCG is not limited to cancer. For example, several studies have shown that this molecule has several neuroprotective properties that could participate in the prevention of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. This is particularly well illustrated by the results of a population survey of 1,000 people living in Singapore aged 55 and over.
In analyzing drinking patterns, researchers found that people who regularly ate tea saw their risk of having a decline in cognitive function reduced by 50% compared to those who did not or very little rarely. This reduction in risk is particularly striking for people who had a copy of the APOE e4 gene, which is genetically at a higher risk of developing Alzheimer’s disease, with a dramatic reduction of 85%. Surprisingly, the protection offered by tea seems much more pronounced for women.
These results show once again how much our lifestyle has a huge impact on our health, both physical and mental. The deterioration of cognitive function associated with aging is not an inevitable phenomenon, against which we can do nothing. Consumption of plants that contain high levels of antioxidant and anti-inflammatory molecules such as green tea, cocoa, turmeric or berries can help reduce the risk of cognitive decline, especially if it is part of a lifestyle overall healthy which includes regular physical activity and maintaining a healthy body weight.