Nutrition can be defined as providing cells and organisms with the materials necessary to support life, generally via food intake. Looking at it another way, in order for the cell or organism to survive in a healthy manner, its food must contain the proper nutrients. Nutrients are the chemicals which the cell or organism uses to live, build and grow, and drive its metabolism; these nutrients must come from the environment. Animal organisms assimilate most nutrients through the digestive process.
Human nutrition comes in three forms: macronutrients, micronutrients and enzymes. Macronutrients are chemical elements that humans consume in the largest quantity including nitrogen, oxygen, carbon, hydrogen, phosphorus, calcium and sulfur. These chemical elements form the compounds carbohydrates, proteins and fats.
Carbohydrates, proteins and fats are considered energy producing nutrients. Carbohydrates are chemical compounds made up of sugars and are classified by the number of sugar (saccharide) units (mono, di, oligo, poly). The more complex the saccharide, the longer it takes for the body to digest it.
Proteins are organic (carbon containing) compounds comprised of amino acids held together with peptide bonds. Some amino acids are essential (must come from food, the body cannot make these).
Fats are complex molecules consisting of glycerin and three fatty acids. Fats are required to keep the membranes in every cell in the body functioning properly. Cholesterol is the most important fat in this regard. The has never been one well-done study not funded by the pharmaceutical industry that showed cholesterol levels have anything to do with heart disease. Even the American Heart Association says cholesterol levels are at best a tertiary risk factor. Fats protect the body from shock, insulate the body and maintain healthy skin and hair. Omega-3 and Omega-6 fatty acids are essential (the body cannot produce them) and serve as anti-inflammatory agents, mood and behavior modulators, and affect DNA activity.
Micronutrients are required in smaller quantities than macronutrients and are considered essential elements because they must come from the food consumed; humans cannot synthesize the micronutrients. Iron, cobalt, chromium, copper, iodine, manganese, selenium, zinc and molybdenum and all micronutrients as are many vitamins.
Enzymes are proteins that work as catalysts for the body’s internal processes. Almost every biological process requires enzymes. Certain drugs or chemicals, temperature and pH can affect enzyme activity.