Overnight tea that has been left for more than 24 hours has a higher chance of becoming moldy and breeding bacteria and mold, so it is not suitable to drink; if it is kept for 8 to 12 hours, you must consider the weather and temperature. It is also easy to deteriorate within 12 hours in summer, and it is easy to spoil in winter. About 12 hours is better; usually, overnight tea within 12 hours is not a big problem. Of course, it is definitely not as fragrant and nutritious as freshly brewed tea, but the nutritional content will be reduced, and drinking it will not harm your health.

It is not advisable to drink overnight tea for three main reasons:

1. Tea contains tea polyphenols, vitamins, catechins, amino acids and other ingredients. Antioxidation is one of the important functions of tea. 1. Tea, vitamin C, etc. are oxidized when exposed to the air for a long time. Tea polyphenols are oxidized into tea pigments, and the antioxidant effect will be weakened, especially for green tea and white tea.

2. After the tea has been left for a long time, tannic acid will be produced, and the tannic acid will be completely dissolved in the tea. If you drink it after getting up early and then have breakfast, tannic acid will react with food to produce oxalic acid. The combination of tannic acid and oxalic acid will cause chemical changes, which can easily lead to stones. At the same time, tannic acid also makes other nutrients more difficult to digest.

3. If overnight tea is left for more than 24 hours, because the tea itself contains sugar and a small amount of protein, it will become moldy under suitable temperature and humidity conditions, producing bacteria and mold, causing diarrhea. Therefore, you should not drink tea for more than 24 hours, especially when the temperature is high in summer.

In addition, for some strong teas, there has been medical evidence that brewing them for longer than a certain limit will cause certain side effects and produce some corresponding harmful substances. In short, the harm of overnight tea is limited to spoiled overnight tea. Non-deteriorated overnight tea will not be harmful to health. On the contrary, overnight tea has many health benefits. It is rich in alcohol and fluorine, which can prevent capillary bleeding.

Extended information:

Notes on drinking tea

1. Pay attention to the differences between the four seasons, that is: drink scented tea in spring, green tea in summer, and green tea in autumn. Tea, drink black tea in winter. The reason is: in spring, people drink scented tea, which can dispel the cold evil accumulated in the human body over the winter. The rich fragrance can promote the generation of yang energy in the human body. In summer, it is better to drink green tea.

Green tea has a bitter and cold taste, which can clear away heat, relieve summer heat, detoxify, quench thirst, and strengthen the heart. In autumn, it is better to drink green tea. This tea is neither cold nor hot, and can eliminate residual heat in the body and restore body fluids. In winter, drinking black tea is the most ideal. Black tea is sweet in taste and warm in nature, and is rich in protein, which can aid digestion, nourish the body, and make the body strong.

2. Pay attention to drinking tea in an appropriate amount, drinking 2 to 6 grams of tea every day. Although tea contains a variety of vitamins and amino acids, drinking tea has certain effects on clearing oil and relieving greasiness, enhancing nerve excitement, and promoting digestion and diuresis. However, drinking more is not always better, and not all people are suitable for drinking tea.

3. Do not drink tea that is too strong. Strong tea will excessively increase the "excitability" of the human body, causing adverse effects on the cardiovascular system, nervous system, etc. People with cardiovascular disease may experience tachycardia or even irregular heartbeat after drinking strong tea, resulting in recurrence of the condition.

People's Daily Online - Can you drink overnight tea? 6 tips on drinking tea

People's Daily - Can you drink overnight tea? Three reasons to stay away from overnight tea