A new study by Qatar University's School of Health Sciences (QU-CHS) and the University of Pennsylvania's School of Nursing in the United States has revealed that higher tea intake is associated with reduced cognitive decline in adults.
The study followed 4,820 Chinese adults aged 55 years and older from 1997 to 2011 with multiple follow-ups. The results showed that older adults who drank 4 or more cups of tea per day scored higher on cognitive function tests, reporting a 25 to 30 percent lower risk of poor memory or memory loss than those who did not drink tea.
The study authors explain that the cognitive benefits of tea may be attributed to a family of compounds called "polyphenols" in tea, which previous studies have shown to have antioxidant and anti-inflammatory effects. The cognitive protection of tea may be the result of the synergistic effect of multiple chemical components, rather than the efficacy of a single ingredient, as tea contains many important nutrients, including vitamin C.
In addition, the researchers also mentioned that previous studies have shown that drinking tea can reduce the concentration of total cholesterol in the blood and reduce the risk of high blood pressure, both of which are related to cognitive dysfunction. Therefore, tea consumption indirectly has a positive impact on cognitive health by reducing the risk of related health problems.
Interestingly, the researchers further explored whether other nutrients in the diet could affect the association between tea and cognition. Iron intake did not have a negative effect on cognitive health in tea drinkers, but it did occur in non-tea drinkers. Therefore, the positive effect of tea on cognitive function may be achieved by countering the negative effects of high-speed intake on cognitive health.
Which tea may be best for reducing Alzheimer's?
Tea can be roughly divided into the following categories according to the degree of fermentation and processing methods:
1. Green tea (unfermented tea): It retains the most original green color of tea and a large number of natural components, such as tea polyphenols, caffeine and vitamins, etc., and is the largest and most widely consumed tea in China.
2. White tea (lightly fermented tea): It is characterized by natural drying or slight fermentation after picking, maintaining the natural form of tea leaves and having a light tea taste.
3. Yellow tea (lightly fermented tea): made by a special "stuffy yellow" process, the tea soup is yellow in color and mellow in taste.
4. Oolong tea (semi-fermented tea): between green tea and black tea, depending on the degree of fermentation, it has both the fragrance of green tea and the mellow of black tea.
5. Black tea (fully fermented tea): After the kneading and fermentation process, the color of the tea leaves changes to reddish-brown, the tea soup is red and bright, and the taste is mellow.
6. Black tea (post-fermented tea): including Pu'er tea, etc., after a long period of accumulation and fermentation, it has a unique aged aroma, and the older it is, the more fragrant it becomes.
According to the above information, green tea has the highest content of tea polyphenols, because green tea is not fermented, and the original tea polyphenols and other natural components of the tea are retained to the greatest extent. Among the green teas, the tea polyphenol content of young leaf green tea was particularly abundant, and the tea polyphenol content of large-leaved tea plants (such as Yunnan large-leaf species) was higher than that of small-leaved species. Therefore, drinking green tea may be one of the most beneficial options for the brain.
How to make tea with high polyphenol content?
- Choose the right teas: Preference is given to young leaf green teas or large-leaf tea leaves, which are high in tea polyphenols.
- Water temperature and tea brewing time: The higher the water temperature and the longer the tea brewing time, the more tea polyphenols will be released. But too high a temperature or too long a time can also destroy other beneficial components in the tea, such as vitamin C, affecting the taste. For green tea, it is recommended to use a water temperature of 80°C to 85°C and steep for 1 to 3 minutes.
- Multiple brews: The first brew can precipitate more tea polyphenols, but the subsequent brews can also continue to release tea polyphenols, especially for pressed tea or old tea, multiple brews can better experience the layering of tea.
- Avoid using too much tea: Although increasing the amount of tea leaves can increase the concentration of tea polyphenols in the tea soup, too much tea may lead to excessive bitterness and astringency, which can affect the drinking experience.
In summary, if you want to brew tea with high polyphenol content, it is important to choose the right type of tea and use the appropriate brewing method.