The document discusses the essential nutrients required by the human body. It defines nutrients as substances in food that keep the body functioning. There are six essential nutrients: water, carbohydrates, proteins, fats, vitamins, and minerals. All nutrients play important roles like providing energy, building tissues, and regulating bodily processes. A balanced diet with variety and moderation from the different food groups is key to obtaining all necessary nutrients. Nutrient deficiencies can occur if the body does not get enough of certain nutrients and can cause symptoms initially or lead to serious health issues if left untreated.