Nutrition Part I: Macro-nutrients & Micro-nutrients

Author: Joseph Krachenfels

Nutrition is defined as the science of food and its relationship to health. Food is composed of a wide distribution of nutrients, which have very specific metabolic effects on the human body. Some of these nutrients are considered to be essential while others are considered to be non-essential.

Essential nutrients are nutrients that cannot be synthesized by the human body and therefore must be derived from food sources. Essential nutrients include vitamins, minerals, amino acids, fatty acids and some carbohydrates as a source of energy. Non-essential nutrients are nutrients which the body has the ability to synthesis from other compounds, as well as, from food sources. Nutrients are generally divided into 2 categories, macronutrients, and micronutrients (Merck Manual 2).

Macronutrients constitute the majority of an individual’s diet, “thereby supplying energy, and the essential nutrients that are needed for growth, maintenance, and activity” (2). Macronutrients include carbohydrates, proteins, fats, macro minerals, and water. Carbohydrates, proteins, and fats are interchangeable as sources of energy, with fats yielding 9 calories per gram, and protein and carbohydrates each yielding 4 calories per gram. For more information on carbohydrates, protein, fats, macro minerals and water please refer to Nutrition Part II Carbohydrates, Nutrition Part III Protein, Nutrition Part IV Fats, Nutrition Part V Macro Minerals and Nutrition Part VI Water.

Micronutrients are vitamins and trace minerals. Vitamins and trace minerals are labeled as micronutrients because the body only requires them in very small amounts. Vitamins are organic substances that we ingest with our foods, and that “act as catalysts, substances that help to trigger other reactions in the body” (Schwarzenegger 674). Trace minerals are inorganic substances that once ingested play a role in a “variety of metabolic processes, and contribute to the synthesis of such elements as glycogen, protein, and fats” (675). For more information on vitamins and trace minerals please refer to Nutrition Part VI Vitamins, and Nutrition Part VII Trace Minerals.

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The Merck Manual Seventeenth Edition, Merck Research Laboratories, 1999.

Arnold Schwarzenegger Encyclopedia of Modern Body Building, Simon & Schuster, 1985.

Mosby’s Medical, Nursing, & Allied Health Dictionary, Mosby, 1998.