Last updated

Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It includes ingestion, absorption, assimilation, biosynthesis, catabolism and excretion. [1]


The science that studies the physiological process of nutrition is called nutritional science (also nutrition science).

Nutritional groups

Organisms primarily provide themselves with carbon in one of two ways: autotrophy (the self-production of organic food) and heterotrophy (the consumption of existing organic carbon). Combined with the source of energy, either light (phototrophy) or chemical (chemotrophy), there are four primary nutritional groups for organisms. [2]


Nutrients are substances used by an organism to survive, grow, and reproduce. The seven major classes of relevant nutrients for animals (including humans) are carbohydrates, dietary fiber, fats, proteins, minerals, vitamins, and water. Nutrients can be grouped as either macronutrients (carbohydrates, dietary fiber, fats, proteins, and water needed in gram quantities) or micronutrients (vitamins and minerals needed in milligram or microgram quantities).


In nutrition, the diet of an organism is the sum of foods it eats, which is largely determined by the availability and palatability of foods.

Human nutrition

Human nutrition deals with the provision of essential nutrients from food that are necessary to support human life and good health. [3]

In humans, poor nutrition can cause deficiency-related diseases such as blindness, anemia, scurvy, preterm birth, stillbirth and cretinism, [4] or nutrient excess health-threatening conditions such as obesity [5] [6] and metabolic syndrome; [7] and such common chronic systemic diseases as cardiovascular disease, [8] diabetes, [9] [10] and osteoporosis. [11] [12] [13] Undernutrition can lead to wasting in acute cases, and stunting of marasmus in chronic cases of malnutrition. [4]

Animal nutrition

Animal nutrition focuses on the dietary nutrients needs of animals, often in comparison (or contrast) to other organisms like plants. Carnivore and herbivore diets are contrasting, with basic nitrogen and carbon proportions vary for their particular foods. Many herbivores rely on bacterial fermentation to create digestible nutrients from indigestible plant cellulose, while obligate carnivores must eat animal meats to obtain certain vitamins or nutrients their bodies cannot otherwise synthesize. Animals generally have a higher requirement of energy in comparison to plants. [14]

Plant nutrition

Plant nutrition is the study of the chemical elements that are necessary for plant growth. [15] There are several principles that apply to plant nutrition. Some elements are directly involved in plant metabolism. However, this principle does not account for the so-called beneficial elements, whose presence, while not required, has clear positive effects on plant growth.

A nutrient that is able to limit plant growth according to Liebig's law of the minimum is considered an essential plant nutrient if the plant cannot complete its full life cycle without it. There are 16 essential plant soil nutrients, besides the three major elemental nutrients carbon and oxygen that are obtained by photosynthetic plants from carbon dioxide in air, and hydrogen, which is obtained from water.

Plants uptake essential elements from the soil through their roots and from the air (consisting of mainly nitrogen and oxygen) through their leaves. Green plants obtain their carbohydrate supply from the carbon dioxide in the air by the process of photosynthesis. Carbon and oxygen are absorbed from the air, while other nutrients are absorbed from the soil. Nutrient uptake in the soil is achieved by cation exchange, wherein root hairs pump hydrogen ions (H+) into the soil through proton pumps. These hydrogen ions displace cations attached to negatively charged soil particles so that the cations are available for uptake by the root. In the leaves, stomata open to take in carbon dioxide and expel oxygen. The carbon dioxide molecules are used as the carbon source in photosynthesis.

Although nitrogen is plentiful in the Earth's atmosphere, very few plants can use this directly. Most plants, therefore, require nitrogen compounds to be present in the soil in which they grow. This is made possible by the fact that largely inert atmospheric nitrogen is changed in a nitrogen fixation process to biologically usable forms in the soil by bacteria. [16]

Plant nutrition is a difficult subject to understand completely, partially because of the variation between different plants and even between different species or individuals of a given clone. Elements present at low levels may cause deficiency symptoms, and toxicity is possible at levels that are too high. Furthermore, deficiency of one element may present as symptoms of toxicity from another element, and vice versa.[ citation needed ]

See also

Related Research Articles

Carbohydrate Organic compound that consists only of carbon, hydrogen, and oxygen

A carbohydrate 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 or may not be different from n). However, not all carbohydrates conform to this precise stoichiometric definition (e.g., uronic acids, deoxy-sugars such as fucose), nor are all chemicals that do conform to this definition automatically classified as carbohydrates (e.g. formaldehyde and acetic acid).

Vitamin Nutrients required by organisms in small amounts

A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient which an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet. Vitamin C can be synthesized by some species but not by others; it is not a vitamin in the first instance but is in the second. The term vitamin does not include the three other groups of essential nutrients: minerals, essential fatty acids, and essential amino acids. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, there are eight vitamers of vitamin E: four tocopherols and four tocotrienols. Some sources list fourteen vitamins, by including choline, but major health organizations list thirteen: vitamin A (as all-trans-retinol, all-trans-retinyl-esters, as well as all-trans-beta-carotene and other provitamin A carotenoids), vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine), vitamin B7 (biotin), vitamin B9 (folic acid or folate), vitamin B12 (cobalamins), vitamin C (ascorbic acid), vitamin D (calciferols), vitamin E (tocopherols and tocotrienols), and vitamin K (phylloquinone and menaquinones).

A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excreted by cells to create non-cellular structures, such as hair, scales, feathers, or exoskeletons. Some nutrients can be metabolically converted to smaller molecules in the process of releasing energy, such as for carbohydrates, lipids, proteins, and fermentation products, leading to end-products of water and carbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of the amino acids that are combined to create proteins, a subset of fatty acids, vitamins and certain minerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. Fungi live on dead or living organic matter and meet nutrient needs from their host.

Human nutrition Provision of essential nutrients necessary to support human life and health

Human nutrition deals with the provision of essential nutrients in food that are necessary to support human life and good health. Poor nutrition is a chronic problem often linked to poverty, food security, or a poor understanding of nutritional requirements. Malnutrition and its consequences are large contributors to deaths, physical deformities, and disabilities worldwide. Good nutrition is necessary for children to grow physically and mentally, and for normal human biological development.


A heterotroph is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but not producers. Living organisms that are heterotrophic include all animals and fungi, some bacteria and protists, and many parasitic plants. The term heterotroph arose in microbiology in 1946 as part of a classification of microorganisms based on their type of nutrition. The term is now used in many fields, such as ecology in describing the food chain.

An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life forms, the nine amino acids humans cannot synthesize are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine.

In the context of nutrition, a mineral is a chemical element required as an essential nutrient by organisms to perform functions necessary for life. However, the four major structural elements in the human body by weight, are usually not included in lists of major nutrient minerals. These four elements compose about 96% of the weight of the human body, and major minerals (macrominerals) and minor minerals compose the remainder.

Plant nutrition Study of the chemical elements and compounds necessary for normal plant life

Plant nutrition is the study of the chemical elements and compounds necessary for plant growth, plant metabolism and their external supply. In its absence the plant is unable to complete a normal life cycle, or that the element is part of some essential plant constituent or metabolite. This is in accordance with Justus von Liebig's law of the minimum. The total essential plant nutrients include seventeen different elements: carbon, oxygen and hydrogen which are absorbed from the air, whereas other nutrients including nitrogen are typically obtained from the soil.

Diet (nutrition) Sum of food consumed by an organism

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. 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.

Vegetarian nutrition Nutritional and human health aspects of vegetarian diets

Vegetarian nutrition is the set of health-related challenges and advantages of vegetarian diets.

Cat food Food for consumption by cats

Cat food is food for consumption by cats. Cats have specific requirements for their dietary nutrients. Certain nutrients, including many vitamins and amino acids, are degraded by the temperatures, pressures and chemical treatments used during manufacture, and hence must be added after manufacture to avoid nutritional deficiency.

Micronutrients are essential elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for example, humans and other animals require numerous vitamins and dietary minerals, whereas plants require specific minerals. For human nutrition, micronutrient requirements are in amounts generally less than 100 milligrams per day, whereas macronutrients are required in gram quantities daily.

Assimilation is the process of absorption of vitamins, minerals, and other chemicals from food within the gastrointestinal tract, as part of the nutrition of an organism. In humans, this is always done with a chemical breakdown and physical breakdown. The second process of bio assimilation is the chemical alteration of substances in the bloodstream by the liver or cellular secretions. Although a few similar compounds can be absorbed in digestion bio assimilation, the bioavailability of many compounds is dictated by this second process since both the liver and cellular secretions can be very specific in their metabolic action. This second process is where the absorbed food reaches the cells via the liver.

Sports nutrition

Sports nutrition is the study and practice of nutrition and diet with regards to improving anyone's athletic performance. Nutrition is an important part of many sports training regimens, being popular in strength sports and endurance sports. Sports nutrition focuses its studies on the type, as well as the quantity of fluids and food taken by an athlete. In addition, it deals with the consumption of nutrients such as vitamins, minerals, supplements and organic substances that include carbohydrates, proteins and fats.

Micronutrient deficiency Medical condition

Micronutrient deficiency or dietary deficiency is not enough of one or more of the micronutrients required for optimal plant or animal health. In humans and other animals they include both vitamin deficiencies and mineral deficiencies, whereas in plants the term refers to deficiencies of essential trace minerals.


Antinutrients are natural or synthetic compounds that interfere with the absorption of nutrients. Nutrition studies focus on antinutrients commonly found in food sources and beverages. Antinutrients may take the form of drugs, chemicals that naturally occur in food sources, proteins, or overconsumption of nutrients themselves. Antinutrients may act by binding to vitamins and minerals, preventing their uptake, or inhibiting enzymes.

Animal nutrition focuses on the dietary nutrients needs of animals, primarily those in agriculture and food production, but also in zoos, aquariums, and wildlife management.

Nutrition is the intake of food, considered in relation to the body's dietary needs. Well-maintained nutrition includes a balanced diet as well as a regular exercise routine. Nutrition is an essential aspect of everyday life as it aids in supporting mental as well as physical body functioning. The National Health and Medical Research Council determines the Dietary Guidelines within Australia and it requires children to consume an adequate amount of food from each of the five food groups, which includes fruit, vegetables, meat and poultry, whole grains as well as dairy products. Nutrition is especially important for developing children as it influences every aspect of their growth and development. Nutrition allows children to maintain a stable BMI, reduces the risks of developing obesity, anemia and diabetes as well as minimises child susceptibility to mineral and vitamin deficiencies.

Like the human practice of veganism, vegan dog foods are those formulated with the exclusion of ingredients that contain or were processed with any part of an animal, or any animal byproduct. Vegan dog food may incorporate the use of fruits, vegetables, cereals, legumes, nuts, vegetable oils, and soya, as well as any other non-animal based foods. The omnivorous domestic canine has evolved to metabolize carbohydrates and thrive on a diet lower in protein, and therefore, a vegan diet is nutritionally adequate for dogs if properly formulated and balanced. Dogs can also thrive on a vegetarian diet.


  1. "nutrition | Definition, Importance, & Food". Encyclopedia Britannica.
  2. Lwoff, A.; C.B. van Niel; P.J. Ryan; E.L. Tatum (1946). Nomenclature of nutritional types of microorganisms (PDF). Cold Spring Harbor Symposia on Quantitative Biology. XI (5th ed.). Cold Spring Harbor, N.Y.: The Biological Laboratory. pp. 302–303.
  3. "human nutrition | Importance, Essential Nutrients, Food Groups, & Facts". Encyclopedia Britannica. Retrieved 29 December 2020.
  4. 1 2 Whitney, Ellie; Rolfes, Sharon Rady (2013). Understanding Nutrition (13 ed.). Wadsworth, Cengage Learning. pp. 667, 670. ISBN   978-1-133-58752-1.
  5. Obesity, Weight Linked to Prostate Cancer Deaths – National Cancer Institute Archived 7 June 2011 at the Wayback Machine . Retrieved on 2011-10-17.
  6. Obesity and Overweight for Professionals: Causes | DNPAO | CDC Archived 24 February 2016 at the Wayback Machine . (16 May 2011). Retrieved on 2011-10-17.
  7. Metabolic syndrome – PubMed Health. Retrieved on 2011-10-17.
  8. Omega-3 fatty acids. (5 October 2011). Retrieved on 2011-10-17.
  9. What I need to know about Eating and Diabetes – National Diabetes Information Clearinghouse. Retrieved on 2011-10-17.
  10. Diabetes Diet and Food Tips: Eating to Prevent and Control Diabetes Archived 20 May 2011 at the Wayback Machine . Retrieved on 2011-10-17.
  11. Osteoporosis & Vitamin D: Deficiency, How Much, Benefits, and More. (7 July 2005). Retrieved on 2011-10-17.
  12. Dietary Supplement Fact Sheet: Vitamin D. Retrieved on 2011-10-17.
  13. Brody, Jane E. (19 March 1998). "Osteoporosis Linked to Vitamin D Deficiency". The New York Times. Archived from the original on 9 March 2008.
  14. National Geographic Society (21 January 2011). "Herbivore". National Geographic Society. Retrieved 1 May 2017.
  15. Allen V. Barker; David J. Pilbeam. Handbook of Plant Nutrition. CRC Press, 2010. p. Preface.
  16. Lindemann, W.C. and Glover C.R. (2003) Nitrogen Fixation by Legumes. New Mexico State University/