Food is any material eaten to provide nutrition to an organism for its proper growth and development. Generally speaking, food is generally of animal, plant or fungal origin, and comprises necessary nutrients, including proteins, fats, carbohydrates, vitamins, or any combination thereof. The human body requires an adequate supply of food throughout the day, including at least six glasses per day; however, human food consumption is not nearly sufficient to meet the nutritional needs of the average person. In most developed countries, a dietary allowance of food is estimated based on income level and country size.
The major categories of food include protein, carbohydrate, fat, mineral components, vitamins and selected bio-active compounds, among which soluble fiber, dietary fiber, protein, vitamin E, potassium, iron, calcium, magnesium, zinc, phosphorus, potassium salt, albumin, cholesterol, phytosterols, monounsaturated fatty acids, sodium, and sodium chloride are the major categories. Among the major dietary fiber groups are pectins, lecithin, and mucilage. The main sources of dietary fiber are nuts, legumes, fresh fruits, cereals, vegetables, and grains.
Amino acids are the chemical precursors of other functional groups of foods. Common examples of amino acids are proteins, nucleic acids, fats, and milk products. Some good sources of amino acids are beans, nuts, fish, eggs, soybeans, legumes, rice, mushrooms, and spinach. Nuts, soybeans, seeds, and whole grains are good sources of protein. Milk products, including cheese and yoghurt, are good sources of both calcium and vitamin D.