About 60% of the human body's weight is water. People are quite sensitive to dehydration; they may feel a dry mouth when they lose about 2% of their body weight in water, and symptoms of dehydration appear when the loss reaches about 10%, which can be life-threatening if it continues. While drinking plain water or mineral water can generally rehydrate the body, drinking the wrong type of water can be fatal in certain situations.
The main causes of human dehydration are: excessive sweating, diarrhea, and vomiting. Regardless of the cause, when the body expels water, it also loses some electrolytes, such as sodium, potassium, calcium, magnesium, and chloride. The function of human cells requires a certain concentration of electrolytes, and a severe electrolyte imbalance can lead to low blood pressure, coma, circulatory failure, and even death. The body has a reservoir of electrolytes, like a balancing pole used when walking on a tightrope, so there is generally no need to worry about imbalance. However, when electrolytes are lost rapidly and in large quantities, the body cannot adjust in time and must replenish them from the outside. This is especially important in the following three situations, where people should promptly replenish electrolytes through drinks like electrolyte beverages.
Exercise. News media often report cases of sudden death after exercise. Besides pre-existing conditions like cardiovascular disease, the loss of electrolytes from intense, prolonged exercise is also a significant trigger. A typical example is the currently popular "marathon," which covers tens of kilometers. Organizers usually set up water stations along the course, typically providing electrolyte drinks, sports drinks, and light saltwater. If one drinks only pure water or ordinary mineral water, it may not be enough to replenish the sodium salt and other essential electrolytes, leading to hyponatremia or an electrolyte imbalance, which in severe cases can trigger sudden death. High temperatures. Humans are sensitive to temperature. Once the temperature exceeds 35°C and the humidity is over 60% (commonly known as a "sauna day"), the body's ability to dissipate heat is compromised. Without air conditioning, one can break into a sweat even while sitting still. To cool down, the body sweats profusely, losing many electrolytes. If not replenished in time and if the person is not moved out of the hot environment, it can lead to severe heatstroke, with a mortality rate as high as 20% to 70%. Although air conditioning is common in many places now, many people still have to work outdoors in the summer, such as salespeople, construction workers, sanitation workers, military police on duty, traffic police, and delivery personnel. They all need to rehydrate promptly and prevent electrolyte loss.
Diarrhea. Most cases of diarrhea are caused by bacteria or viruses and can resolve on their own without antibiotics. However, diarrhea can lead to significant dehydration and electrolyte imbalance in the body, which can be fatal in severe cases. How can you tell if you are dehydrated? Press firmly on your calf; if the indentation does not disappear quickly after you release the pressure, you should be cautious of dehydration and electrolyte imbalance. Additionally, be aware of symptoms like dizziness, blurred vision, sunken eyes, and weakness in the limbs. Patients with diarrhea should not just drink plain water; they also need to replenish electrolytes. A simple method is to drink light saltwater, but if signs of significant dehydration or electrolyte imbalance are already present, it is best to seek medical treatment. It is even better to keep some "oral rehydration salts" at home, which are generally available in pharmacies. In an emergency, drinking beverages that can replenish electrolytes can also help, but avoid energy drinks as their high sugar content is not good for the stomach to recover.