Nutrition, nourishment, or aliment, is the supply of materials - food - required by organisms and cells to stay alive. In science and human medicine, nutrition is the science or practice of consuming and utilizing foods.
Nutritional science studies how the body breaks food down (catabolism) and how it repairs and creates cells and tissue (anabolism). Catabolism and anabolism combined can also be referred to as metabolism. Nutritional science also examines how the body responds to food.
Fast facts on nutrition
• The human body requires seven major types of nutrients.
• Not all nutrients provide energy but are still important, such as water and fiber.
• Micronutrients are important but required in smaller amounts.
• Vitamins are essential organic compounds that the human body cannot synthesize. Vitamins are essential organic compounds that the human body cannot synthesize.
As molecular biology, biochemistry, and genetics advance, nutrition has become more focused on metabolism and metabolic pathways - biochemical steps through which substances inside us are transformed from one form to another.
Nutrition also focuses on how diseases, conditions, and problems can be prevented or reduced with a healthy diet.
Similarly, nutrition involves identifying how certain diseases and conditions may be caused by dietary factors, such as poor diet (malnutrition), food allergies, and food intolerances.
Nutrition is the study of nutrients in food, how the body uses nutrients, and the relationship between diet, health, and disease.
Energy macronutrients provide energy, which is measured either in kilocalories (kcal or calories) or Joules. 1 kilocalorie (calorie) = 4185.8 joules. Energy macronutrients include:
Carbohydrates - 4 kcal per gram
Carbohydrate molecules include monosaccharides (glucose, fructose, galactose), disaccharides, and polysaccharides (starch).
Nutritionally, polysaccharides are favored over monosaccharides because they are more complex and therefore take longer to break down and be absorbed into the bloodstream; this means that they do not cause major spikes in blood sugar levels, which are linked to heart and vascular diseases.
Proteins - 4 kcal per gram
There are 20 amino acids - organic compounds found in nature that combine to form proteins. Some amino acids are essential, meaning they need to be consumed. Other amino acids are non-essential because the body can make them.
Fats - 9 kcal per gram
Fats - 9 kcal per gram
Fats are triglycerides - three molecules of fatty acid combined with a molecule of the alcohol glycerol. Fatty acids are simple compounds (monomers) while triglycerides are complex molecules (polymers).
Fats are required in the diet for health as they serve many functions, including lubricating joints, helping organs produce hormones, assisting in absorption of certain vitamins, reducing inflammation, and preserving brain health.