Nutrition
Nutrition is the provision, to cells and organisms, of the materials necessary (in the form of food) to support life. Many common health problems can be prevented or alleviated with good nutrition.
The diet of an organism refers to what it eats. Dietitians are health professionals who specialize in human nutrition, meal planning, economics, preparation, and so on. They are trained to provide safe, evidence-based dietary advice and management to individuals (in health and disease), as well as to institutions.
Poor diet can have an injurious impact on health, causing deficiency diseases such as scurvy, beriberi, and kwashiorkor; health-threatening conditions like obesity and metabolic syndrome, and such common chronic systemic diseases as cardiovascular disease, diabetes, and osteoporosis.
There are seven major classes of nutrients: carbohydrates, fats, fiber, minerals, proteins, vitamins, and water.
These nutrient classes can be generally grouped into the categories of macronutrients (needed in relatively large amounts), and micronutrients (needed in smaller quantities). The macronutrients are carbohydrates, fats, fiber, proteins and water. The other nutrient classes are micronutrients.
The macronutrients (excluding fiber and water) provide energy, which is measured in kilocalories, often called "Calories" and written with a capital C to distinguish them from small calories. Carbohydrates and proteins provide four (4) Calories of energy per gram, while fats provide nine (9) Calories per gram.[1] Vitamins, minerals, fiber, and water do not provide energy, but are necessary for other reasons.
Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Protein molecules contain nitrogen atoms in addition to carbon, hydrogen, and oxygen. The nitrogen-containing components of protein, called amino acids, fulfill many roles other than energy metabolism, and when they are used as fuel, getting rid of the...
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