Principles of Nutrition

1. Digestion – process by which food substances are changed into forms that can be absorbed through cell membranes
2. Absorption – the taking in of substance by cells or membranes
3. Metabolism – sum of all physical and chemical processes by which a living organism is formed and maintained and by which energy is made available
4. Storage – some nutrients are stored when not used to provide energy; e.g. carbohydrates are stored either as glycogen or as fat
5. Elimination – process of discarding unnecessary substances through evaporation, excretion

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