Definition And Classification......( Food )

Plants, algae, and some microorganisms use photosynthesis to make some of their own nutrients.

Water is found in nearly all foods and has been defined as food by itself. Water has no food energy, and fibers have low energy densities, or food energy relative to volume, some providing none, while fat is the most energy-dense component.

Some inorganic substances are also essential for plant and animal functioning

Human food can be classified in various ways, either by related content or by how it is processed.The number and composition of food groups can vary. Most systems include four basic groups described by their origins and relative nutritional functions: vegetables and fruit, cereals and bread, dairy, and meat.

Studies that look into diet quality group food into whole grains, refined grains, vegetables, fruits, nuts, legumes, eggs, dairy products, fish, red meat, processed meat, and sugar-sweetened beverages.

The Food and Agriculture Organization and World Health Organization use a system with eighteen or nineteen[a] food classifications, including: cereals and their products; roots, tubers, plantains and their products; pulses, seeds and nuts and their products; milk and milk products; eggs and their products; fish, shellfish and their products; meat and meat products; insects, grubs and their products; vegetables and their products; fruits and their products; fats and oils; sweets and sugars; spices and condiments; beverages; foods for particular nutritional uses; food additives; composite dishes; and savory snacks.