Food

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File:Good Food Display - NCI Visuals Online.jpg

Display of various foods

Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin and contains essential nutrients such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism's cells to provide energy, maintain life, or stimulate growth. Different species of animals have different feeding behaviours that satisfy the needs of their metabolisms and have evolved to fill a specific ecological niche within specific geographical contexts.

Omnivorous humans are highly adaptable and have adapted to obtaining food in many different ecosystems. Humans generally use cooking to prepare food for consumption. The majority of the food energy required is supplied by the industrial food industry, which produces food through intensive agriculture and distributes it through complex food processing and food distribution systems. This system of conventional agriculture relies heavily on fossil fuels, which means that the food and agricultural systems are one of the major contributors to climate change, accounting for as much as 37% of total greenhouse gas emissions.<ref>Template:Cite book</ref>

The food system has a significant impact on a wide range of other social and political issues, including sustainability, biological diversity, economics, population growth, water supply, and food security. Food safety and security are monitored by international agencies, like the International Association for Food Protection, the World Resources Institute, the World Food Programme, the Food and Agriculture Organization, and the International Food Information Council.

Definition and classificationEdit

Food is any substance consumed to provide nutritional support and energy to an organism.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=":6" /> It can be raw, processed, or formulated and is consumed orally by animals for growth, health, or pleasure. Food is mainly composed of water, lipids, proteins, and carbohydrates. Minerals (e.g., salts) and organic substances (e.g., vitamins) can also be found in food.<ref>Template:Cite journal</ref> Plants, algae, and some microorganisms use photosynthesis to make some of their own nutrients.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Water is found in many foods and has been defined as food by itself.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Water and fiber have low energy densities, or calories, while fat is the most energy-dense component.<ref name=":6">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Some inorganic (non-food) elements are also essential for plant and animal functioning.<ref>Template:Cite journal</ref>

Human food can be classified in various ways, either by related content or by how it is processed.<ref>Template:Cite journal</ref> The number and composition of food groups can vary. Most systems include four basic groups that describe their origin and relative nutritional function: Vegetables and Fruit, Cereals and Bread, Dairy, and Meat.<ref>Template:Cite book</ref> Studies that look into diet quality group food into whole grains/cereals, refined grains/cereals, vegetables, fruits, nuts, legumes, eggs, dairy products, fish, red meat, processed meat, and sugar-sweetened beverages.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> The Food and Agriculture Organization and World Health Organization use a system with nineteen food classifications: cereals, roots, pulses and nuts, milk, eggs, fish and shellfish, meat, insects, vegetables, fruits, fats and oils, sweets and sugars, spices and condiments, beverages, foods for nutritional uses, food additives, composite dishes and savory snacks.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Food sourcesEdit

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A typical aquatic food web

In a given ecosystem, food forms a web of interlocking chains with primary producers at the bottom and apex predators at the top.<ref name=":1">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Other aspects of the web include detrovores (that eat detritis) and decomposers (that break down dead organisms).<ref name=":1" /> Primary producers include algae, plants, bacteria and protists that acquire their energy from sunlight.<ref>Template:Cite book</ref> Primary consumers are the herbivores that consume the plants, and secondary consumers are the carnivores that consume those herbivores. Some organisms, including most mammals and birds, have diets consisting of both animals and plants, and are considered omnivores.<ref name=":2">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The chain ends with the apex predators, the animals that have no known predators in its ecosystem.<ref>Template:Cite journal</ref> Humans are considered apex predators.<ref>Template:Cite journal</ref>

Humans are omnivores, finding sustenance in vegetables, fruits, cooked meat, milk, eggs, mushrooms and seaweed.<ref name=":2" /> Cereal grain is a staple food that provides more food energy worldwide than any other type of crop.<ref>Template:Cite news</ref> Corn (maize), wheat, and rice account for 87% of all grain production worldwide.<ref name="prodstat">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite book</ref> Just over half of the world's crops are used to feed humans (55 percent), with 36 percent grown as animal feed and 9 percent for biofuels.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Fungi and bacteria are also used in the preparation of fermented foods like bread, wine, cheese and yogurt.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

PhotosynthesisEdit

During photosynthesis, energy from the sun is absorbed and used to transform water and carbon dioxide in the air or soil into oxygen and glucose. The oxygen is then released, and the glucose stored as an energy reserve.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Photosynthetic plants, algae and certain bacteria often represent the lowest point of the food chains,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite journal</ref> making photosynthesis the primary source of energy and food for nearly all life on earth.<ref>Template:Cite journal</ref>

Plants also absorb important nutrients and minerals from the air, natural waters, and soil.<ref>Template:Cite book</ref> Carbon, oxygen and hydrogen are absorbed from the air or water and are the basic nutrients needed for plant survival.<ref name=":13">Template:Cite journal</ref> The three main nutrients absorbed from the soil for plant growth are nitrogen, phosphorus and potassium, with other important nutrients including calcium, sulfur, magnesium, iron boron, chlorine, manganese, zinc, copper molybdenum and nickel.<ref name=":13" />

MicroorganismsEdit

Bacteria and other microorganisms also form the lower rungs of the food chain. They obtain their energy from photosynthesis or by breaking down dead organisms, waste or chemical compounds. Some form symbiotic relationships with other organisms to obtain their nutrients.<ref>Template:Citation</ref> Bacteria provide a source of food for protozoa,<ref>Template:Citation</ref> who in turn provide a source of food for other organisms such as small invertebrates.<ref>Template:Citation</ref> Other organisms that feed on bacteria include nematodes, fan worms, shellfish and a species of snail.

In the marine environment, plankton (which includes bacteria, archaea, algae, protozoa and microscopic fungi)<ref name="Lawton-2024-02-10">Template:Cite journal</ref> provide a crucial source of food to many small and large aquatic organisms.

Without bacteria, life would scarcely exist because bacteria convert atmospheric nitrogen into nutritious ammonia. Ammonia is the precursor to proteins, nucleic acids, and most vitamins. Since the advent of the industrial process for nitrogen fixation, the Haber-Bosch Process, the majority of ammonia in the world is human-made.<ref>Template:Cite book</ref>

PlantsEdit

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Foods from plant sources

Plants as a food source are divided into seeds, fruits, vegetables, legumes, grains and nuts.<ref name=":0">Template:Cite book</ref> Where plants fall within these categories can vary, with botanically described fruits such as the tomato, squash, pepper and eggplant or seeds like peas commonly considered vegetables.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Food is a fruit if the part eaten is derived from the reproductive tissue, so seeds, nuts and grains are technically fruit.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=":7">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> From a culinary perspective, fruits are generally considered the remains of botanically described fruits after grains, nuts, seeds and fruits used as vegetables are removed.<ref name=":8" /> Grains can be defined as seeds that humans eat or harvest, with cereal grains (oats, wheat, rice, corn, barley, rye, sorghum and millet) belonging to the Poaceae (grass) family<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and pulses coming from the Fabaceae (legume) family.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Whole grains are foods that contain all the elements of the original seed (bran, germ, and endosperm).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Nuts are dry fruits, distinguishable by their woody shell.<ref name=":8">Template:Cite journal</ref>

Fleshy fruits (distinguishable from dry fruits like grain, seeds and nuts) can be further classified as stone fruits (cherries and peaches), pome fruits (apples, pears), berries (blackberry, strawberry), citrus (oranges, lemon), melons (watermelon, cantaloupe), Mediterranean fruits (grapes, fig), tropical fruits (banana, pineapple).<ref name=":8" /> Vegetables refer to any other part of the plant that can be eaten, including roots, stems, leaves, flowers, bark or the entire plant itself.<ref name=":4">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> These include root vegetables (potatoes and carrots), bulbs (onion family), flowers (cauliflower and broccoli), leaf vegetables (spinach and lettuce) and stem vegetables (celery and asparagus).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=":4" />

The carbohydrate, protein and lipid content of plants is highly variable. Carbohydrates are mainly in the form of starch, fructose, glucose and other sugars.<ref name=":0" /> Most vitamins are found from plant sources, with the exception of vitamin D and vitamin B₁₂. Minerals can also be plentiful or not. Fruit can consist of up to 90% water, contain high levels of simple sugars that contribute to their sweet taste, and have a high vitamin C content.<ref name=":0" /><ref name=":8" /> Compared to fleshy fruit (excepting Bananas) vegetables are high in starch,<ref>Template:Cite journal</ref> potassium, dietary fiber, folate and vitamins and low in fat and calories.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Grains are more starch based<ref name=":0" /> and nuts have a high protein, fiber, vitamin E and B content.<ref name=":8" /> Seeds are a good source of food for animals because they are abundant and contain fiber and healthful fats, such as omega-3 fats.<ref name=":5" /><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Complicated chemical interactions can enhance or depress bioavailability of certain nutrients. Phytates can prevent the release of some sugars and vitamins.<ref name=":0" />

Animals that only eat plants are called herbivores, with those that mostly just eat fruits known as frugivores,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> while leaf and shoot eaters are folivores (pandas) and wood eaters termed xylophages (termites).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Frugivores include a diverse range of species from annelids to elephants, chimpanzees and many birds.<ref>Template:Cite journal</ref><ref>Template:Cite book</ref><ref>Template:Cite book</ref> About 182 fish consume seeds or fruit.<ref>Template:Cite journal</ref> Animals (domesticated and wild) use as many types of grasses that have adapted to different locations as their main source of nutrients.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Humans eat thousands of plant species; there may be as many as 75,000 edible species of angiosperms, of which perhaps 7,000 are often eaten.<ref>Template:Cite journal</ref> Plants can be processed into breads, pasta, cereals, juices and jams or raw ingredients such as sugar, herbs, spices and oils can be extracted.<ref name=":0" /> Oilseeds are pressed to produce rich oilsTemplate:Snd⁣sunflower, flaxseed, rapeseed (including canola oil) and sesame.<ref name="McGee9">McGee, Chapter 9.</ref>

Many plants and animals have coevolved in such a way that the fruit is a good source of nutrition for the animal, who then excretes the seeds some distance away, allowing greater dispersal.<ref>Template:Cite journal</ref> Even seed predation can be mutually beneficial, as some seeds can survive the digestion process.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> Insects are major eaters of seeds,<ref name=":5">Template:Cite journal</ref> with ants being the only real seed dispersers.<ref>Template:Cite book</ref> Birds, although being major dispersers,<ref>Template:Cite journal</ref> only rarely eat seeds as a source of food and can be identified by their thick beak that is used to crack open the seed coat.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Mammals eat a more diverse range of seeds, as they are able to crush harder and larger seeds with their teeth.<ref>Template:Cite journal</ref>

AnimalsEdit

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Various raw meats

Animals are used as food either directly or indirectly. This includes meat, eggs, shellfish and dairy products like milk and cheese.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> They are an important source of protein and are considered complete proteins for human consumption as they contain all the essential amino acids that the human body needs.<ref name=":9">Template:Cite book</ref> One Template:Convert steak, chicken breast or pork chop contains about 30 grams of protein. One large egg has 7 grams of protein. A Template:Convert serving of cheese has about 15 grams of protein. And Template:Cups of milk has about 8 grams of protein.<ref name=":9" /> Other nutrients found in animal products include calories, fat, essential vitamins (including B12) and minerals (including zinc, iron, calcium, magnesium).<ref name=":9" />

Food products produced by animals include milk produced by mammary glands, which in many cultures is drunk or processed into dairy products (cheese, butter, etc.). Eggs laid by birds and other animals are eaten and bees produce honey, a reduced nectar from flowers that is used as a popular sweetener in many cultures. Some cultures consume blood, such as in blood sausage, as a thickener for sauces, or in a cured, salted form for times of food scarcity, and others use blood in stews such as jugged hare.<ref>Davidson, 81–82.</ref>

TasteEdit

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Animals, specifically humans, typically have five different types of tastes: sweet, sour, salty, bitter, and umami. The differing tastes are important for distinguishing between foods that are nutritionally beneficial and those which may contain harmful toxins.<ref name=":10">Template:Cite journal</ref> As animals have evolved, the tastes that provide the most energy are the most pleasant to eat while others are not enjoyable,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> although humans in particular can acquire a preference for some substances which are initially unenjoyable.<ref name=":10" /> Water, while important for survival, has no taste.<ref>Template:Cite news</ref>

Sweetness is almost always caused by a type of simple sugar such as glucose or fructose, or disaccharides such as sucrose, a molecule combining glucose and fructose.<ref name="New Oxford American Dictionary">New Oxford American Dictionary</ref> Sourness is caused by acids, such as vinegar in alcoholic beverages. Sour foods include citrus, specifically lemons and limes. Sour is evolutionarily significant as it can signal a food that may have gone rancid due to bacteria.<ref>States "having an acid taste like lemon or vinegar: she sampled the wine and found it was sour. (of food, esp. milk) spoiled because of fermentation." New Oxford American Dictionary</ref> Saltiness is the taste of alkali metal ions such as sodium and potassium. It is found in almost every food in low to moderate proportions to enhance flavor. Bitter taste is a sensation considered unpleasant characterised by having a sharp, pungent taste. Unsweetened dark chocolate, caffeine, lemon rind, and some types of fruit are known to be bitter. Umami, commonly described as savory, is a marker of proteins and characteristic of broths and cooked meats.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Foods that have a strong umami flavor include cheese, meat and mushrooms.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

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Catfish have millions of taste buds covering their entire body.

While most animals taste buds are located in their mouth, some insects taste receptors are located on their legs and some fish have taste buds along their entire body.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=":11">Template:Cite journal</ref> Dogs, cats and birds have relatively few taste buds (chickens have about 30),<ref name=":12">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> adult humans have between 2000 and 4000,<ref>Template:Cite book</ref> while catfish can have more than a million.<ref name=":11" /> Herbivores generally have more than carnivores as they need to tell which plants may be poisonous.<ref name=":12" /> Not all mammals share the same tastes: some rodents can taste starch, cats cannot taste sweetness, and several carnivores (including hyenas, dolphins, and sea lions) have lost the ability to sense up to four of the five taste modalities found in humans.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

DigestionEdit

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Food is broken into nutrient components through digestive process.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Proper digestion consists of mechanical processes (chewing, peristalsis) and chemical processes (digestive enzymes and microorganisms).<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> The digestive systems of herbivores and carnivores are very different as plant matter is harder to digest. Carnivores mouths are designed for tearing and biting compared to the grinding action found in herbivores.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Herbivores however have comparatively longer digestive tracts and larger stomachs to aid in digesting the cellulose in plants.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Food safetyEdit

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According to the World Health Organization (WHO), about 600 million people worldwide get sick and 420,000 die each year from eating contaminated food.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=":3">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Diarrhea is the most common illness caused by consuming contaminated food, with about 550 million cases and 230,000 deaths from diarrhea each year. Children under five years of age account for 40% of the burden of foodborne illness, with 125,000 deaths each year.<ref name=":3" /><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

A 2003 World Health Organization (WHO) report concluded that about 30% of reported food poisoning outbreaks in the WHO European Region occur in private homes.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> According to the WHO and CDC, in the US alone, annually, there are 76 million cases of foodborne illness leading to 325,000 hospitalizations and 5,000 deaths.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

From 2011 to 2016, on average, there were 668,673 cases of foodborne illness and 21 deaths each year.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In addition, during this period, 1,007 food poisoning outbreaks with 30,395 cases of food poisoning were reported.<ref name=":3" />