Nutrition is: the science that links food to health and disease, it includes the processes by which the human organism ingests, digest, absorbs, transports and excretes food substances. Nutrient is: a substance in food that provides energy and structure to the body and regulates. Essential nutrients: omission leads to decline, regain normal function when restored in diet, has speci c biologic functions. The six classes of nutrients: carbs, lipids, proteins, vitamins, minerals, water. Nutrient functional categories: provides calories, for growth, development, and maintenance, regulates body processes. Carbohydrates: source of calories (~4 kcal/gm, simple sugars, complex. Thursday, january 19, 2017: source of calories (~9 kcal/gm, fats and oils, do not dissolve in water, animal fats (solid, plant oils (liquids, essential fatty acids. Proteins: source of calories (~4 kcal/gm, structural material, amino acids = building blocks. Vitamins: enable chemical reactions, fat soluble. Minerals: inorganic substances, numerous functions in the body, major and trace minerals, yield no energy.