Stagnant boiled water
After being left for a long time, the nitrogen-containing organic matter in boiled water continuously decomposes into nitrites. Especially for boiled water that has been stored for an extended period, bacterial contamination is inevitable. This accelerates the decomposition of nitrogen-containing organic matter, leading to the generation of more nitrites. After drinking such water, nitrites combine with hemoglobin, impairing the blood's ability to transport oxygen.
Therefore, boiled water that has been in a thermos for days, the remaining water from multiple boilings, and water that has been boiling on a stove for a long time have all had their composition altered and are no longer drinkable. You should drink water that has been boiled once and consumed within 24 hours. In addition, various bottled and桶装 (barreled) purified and mineral waters should not be stored for too long. Large bottles or barrels of purified and mineral water should not be consumed after 3 days.
Salt water
Some people believe that drinking light salt water is beneficial to health, so they drink it in the morning. This understanding is incorrect. While it is true that drinking light salt water is beneficial, it is necessary for replenishing fluids after sweating in the summer. However, for replenishing fluids upon waking, it is not only unbeneficial but also a harmful practice that endangers health.
Physiological research suggests that during a full night's sleep, a person consumes no water, yet respiration, sweating, and urination continue. These physiological activities consume and lose a significant amount of water. Upon waking in the morning, the blood is in a concentrated state. Drinking a certain amount of plain water can quickly dilute the blood, correcting the hyperosmolar dehydration from the night. Drinking salt water, on the other hand, would worsen the hyperosmolar dehydration, making one feel even more thirsty. Furthermore, the morning is the first peak of elevated blood pressure in the body. Drinking salt water will further increase blood pressure, which is harmful to health.
Beverages
The first glass of water in the morning should preferably not be commercially available beverages like juice, cola, soda, coffee, or milk. Most carbonated drinks like soda and cola contain citric acid, which accelerates the excretion of calcium during metabolism, reducing calcium levels in the blood. Long-term consumption can lead to calcium deficiency. Other beverages have a diuretic effect; drinking them in the morning not only fails to effectively replenish the body's needed fluids but also increases the body's demand for water,反而 causing dehydration.
Juice, milk, and coffee are also not suitable as the first beverage in the morning because these substances cannot provide the water the body needs most at that time. They also cause the digestive and absorption systems to work when the body is already dehydrated, which is not conducive to health.
Tap water
Some people are in the habit of turning on the tap in the morning and drinking a glass of tap water. This is incorrect. The tap water that has been stagnant in the pipes and faucet overnight is still. This water and the metal pipe walls and faucet chambers undergo hydration reactions, creating metal-contaminated water. Furthermore, residual microorganisms in the tap water can multiply. This water contains a large amount of substances harmful to the human body and may harbor an acute respiratory infectious pathogen that threatens human health—Legionella bacteria. Therefore, the tap water that flows out first in the morning is stagnant water and is not drinkable. So, if you have this habit, please correct it immediately to avoid harming your health.