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Nutrients are components in foods that an organism uses to survive and grow. Macronutrients provide the bulk energy an organism's metabolic system needs to function while micronutrients provide the necessary cofactors for metabolism to be carried out. Both types of nutrients can be acquired from the environment.〔Whitney, Elanor and Sharon Rolfes. 2005. ''Understanding Nutrition, 10th edition'', p 6. Thomson-Wadsworth.〕 Micronutrients are used to build and repair tissues and to regulate body processes while macronutrients are converted to, and used for, energy. Methods of nutrient intake are different for plants and animals. Plants take in nutrients directly from the soil through their roots and from the atmosphere through their leaves. Animals and protists have specialized digestive systems that work to break down macronutrients for energy and utilize micronutrients for both metabolism and anabolism (constructive synthesis) in the body. Organic nutrients consist of carbohydrates, fats, proteins (or their building blocks, amino acids), and vitamins. Inorganic chemical compounds such as dietary minerals, water, and oxygen may also be considered nutrients. A nutrient is considered essential if it must be obtained from an external source either because the organism cannot synthesize it or because insufficient quantities are produced. Nutrients needed in very small amounts are called micronutrients while those needed in large quantities are called macronutrients. The effects of nutrients are dose-dependent; shortages are called deficiencies. ==Types of nutrient== (詳細はchemical elements humans consume in the largest quantities are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulphur, or CHNOPS. * The classes of chemical compounds humans consume in the largest quantities and which provide bulk energy are carbohydrates, proteins, and fats. Water and atmospheric oxygen also must be consumed in large quantities, but are not always considered "food" or "nutrients". * Calcium, salt (sodium and chloride), magnesium, and potassium (along with phosphorus and sulfur) are sometimes added to the list of macronutrients because they are required in large quantities compared to other vitamins and minerals. They are sometimes referred to as the macrominerals. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「nutrient」の詳細全文を読む スポンサード リンク
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