Food
Food is usually of plant, animal, or fungal origin and contains essential nutrients such as carbohydrates, fats, proteins, vitamins, or minerals.
Most systems include four basic groups that describe their origin and relative nutritional function: Vegetables and Fruit, Cereals and Bread, Dairy, and Meat.
[13] In a given ecosystem, food forms a web of interlocking chains with primary producers at the bottom and apex predators at the top.
[14] Other aspects of the web include detrovores (that eat detritis) and decomposers (that break down dead organisms).
[14] Primary producers include algae, plants, bacteria and protists that acquire their energy from sunlight.
Some organisms, including most mammals and birds, diet consists of both animals and plants, and they are considered omnivores.
[18] Humans are omnivores, finding sustenance in vegetables, fruits, cooked meat, milk, eggs, mushrooms and seaweed.
[24] 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.
[29] Carbon, oxygen and hydrogen are absorbed from the air or water and are the basic nutrients needed for plant survival.
[33] 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)[34] provide a crucial source of food to many small and large aquatic organisms.
[35] Plants as a food source are divided into seeds, fruits, vegetables, legumes, grains and nuts.
[36] 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.
[40] 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[41] and pulses coming from the Fabaceae (legume) family.
[36][40] Compared to fleshy fruit (excepting Bananas) vegetables are high in starch,[46] potassium, dietary fiber, folate and vitamins and low in fat and calories.
[55] Animals (domesticated and wild) use as many types of grasses that have adapted to different locations as their main source of nutrients.
[57] Plants can be processed into breads, pasta, cereals, juices and jams or raw ingredients such as sugar, herbs, spices and oils can be extracted.
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.
[68] Animals, specifically humans, typically have five different types of tastes: sweet, sour, salty, bitter, and umami.
[69] As animals have evolved, the tastes that provide the most energy are the most pleasant to eat while others are not enjoyable,[70] although humans in particular can acquire a preference for some substances which are initially unenjoyable.
Umami, commonly described as savory, is a marker of proteins and characteristic of broths and cooked meats.
[76][77] Dogs, cats and birds have relatively few taste buds (chickens have about 30),[78] adult humans have between 2000 and 4000,[79] while catfish can have more than a million.
Carnivores mouths are designed for tearing and biting compared to the grinding action found in herbivores.
[85][86] According to the World Health Organization (WHO), about 600 million people worldwide get sick and 420,000 die each year from eating contaminated food.
