Dietary fiber is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. It has two main components: Soluble fiber – which dissolves in water – is generally fermented in the colon into gases and physiologically active by-products, such as short-chain fatty acids produced in the colon by gut bacteria. Fermentable fibers are called prebiotic fibers. Examples are beta-glucans (in oats, barley, and mushrooms) and raw guar gum. An exception is psyllium, which is a soluble, viscous, nonfermented fiber. Psyllium is a bulking fiber that retains water as it moves through the digestive system, easing defecation. Soluble fiber is generally viscous and delays gastric emptying which, in humans, can result in an extended feeling of fullness. Exceptions are inulin (in onions), wheat dextrin, oligosaccharides, and resistant starches (in legumes and bananas), which are nonviscous. Insoluble fiber – which does not...
Fats are one of the three main macronutrients, along with carbohydrates and proteins. Fat molecules consist of primarily carbon and hydrogen atoms and are therefore hydrophobic and are soluble in organic solvents and insoluble in water. Examples include cholesterol, phospholipids, and triglycerides. The terms lipid, oil, and fat are often confused. Lipid is the general term, though a lipid is not necessarily a triglyceride. Oil normally refers to a lipid with short or unsaturated fatty acid chains that is liquid at room temperature, while fat (in the strict sense) specifically refers to lipids that are solids at room temperature – however, fat (in the broad sense) may be used in food science as a synonym for lipid. Fat is an important foodstuff for many forms of life, and fats serve both structural and metabolic functions. They are a necessary part of the diet of most heterotrophs (including humans) and are...
A carbohydrate (/kɑːrboʊˈhaɪdreɪt/) is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula Cm(H2O)n (where m may be different from n). This formula holds true for monosaccharides. Some exceptions exist; for example, deoxyribose, a sugar component of DNA, has the empirical formula C5H10O4. The carbohydrates are technically hydrates of carbon; structurally it is more accurate to view them as aldoses and ketoses. The term is most common in biochemistry, where it is a synonym of saccharide, a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides and disaccharides, the smallest (lower molecular weight) carbohydrates, are commonly referred to as sugars. The word saccharide comes from the Greek word σάκχαρον (sákkharon), meaning "sugar". While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides very often end...
In nutrition, diet is the sum of food consumed by a person or other organism. The word diet often implies the use of specific intake of nutrition for health or weight-management reasons (with the two often being related). Although humans are omnivores, each culture and each person holds some food preferences or some food taboos. This may be due to personal tastes or ethical reasons. Individual dietary choices may be more or less healthy.
Complete nutrition requires ingestion and absorption of vitamins, minerals, essential amino acids from protein and essential fatty acids from fat-containing food, also food energy in the form of carbohydrate, protein, and fat. Dietary habits and choices play a significant role in the quality of life, health and longevity.
Nutrition is the science that interprets the nutrients and other substances in food in relation to maintenance, growth, reproduction, health and disease of an organism. It includes food intake, absorption, assimilation, biosynthesis, catabolism and excretion.
The diet of an organism is what it eats, which is largely determined by the availability and palatability of foods. For humans, a healthy diet includes preparation of food and storage methods that preserve nutrients from oxidation, heat or leaching, and that reduces risk of foodborne illnesses. The seven major classes of human nutrients are carbohydrates, fats, fiber, minerals, proteins, vitamins, and water.
Nutrients can be grouped as either macronutrients or micronutrients (needed in small quantities).
In humans, an unhealthy diet can cause deficiency-related diseases such as blindness, anemia, scurvy, preterm birth, stillbirth and cretinism, or nutrient excess health-threatening conditions such as obesity and metabolic syndrome; and such common chronic systemic diseases as cardiovascular disease, diabetes, and osteoporosis.
Undernutrition can lead to wasting in acute cases, and the stunting of marasmus in chronic cases of malnutrition.
