Nutrient

A chemical or element vital for growth, metabolism and essential bodily functions. Important nutrients required by the body include carbohydrates, fats, protein, vitamins, minerals and fluids. A nutrient is deemed essential for the body and must be obtained via an external source, such as food, drink and supplements. Those nutrients, such as selenium and chromium, that are only required in small amounts are called micronutrients, while macronutrients, such as carbon and oxygen, are needed in larger quantities.