Which nutrient can humans not live without?

Water is a vital nutrient that humans cannot live without, as it is essential for numerous bodily functions. It plays a crucial role in maintaining hydration, regulating body temperature, transporting nutrients, and eliminating waste. The human body is composed of about 60% water, which highlights its importance in sustaining life. Even a slight dehydration can lead to serious health problems, while a complete lack of water can result in death within just a few days.

While proteins, fats, and vitamins are also important nutrients necessary for overall health and bodily function, the body can survive without them for a longer duration compared to water. For instance, individuals can live for weeks without food, as long as they have access to water. Thus, water is the most critical nutrient for survival, making it indispensable for life.