This document defines basic nutrition concepts including nutrition, food, nutrients, and nutritional status. It classifies nutrients according to function, chemical nature, essentiality, and concentration. The six major nutrients are proteins, carbohydrates, fats, minerals, vitamins, and water. Nutritional status can be optimum, undernutrition due to lack of nutrients, or overnutrition due to excessive nutrients leading to harmful effects like obesity. Malnutrition is caused by a faulty diet as the primary factor or secondary factors that interfere with nutrient digestion, metabolism, or excretion.