Food is a substance used to sustain life and provide energy. People get nutrients from plants (which convert sunlight to food through photosynthesis) and animals that eat plants or other animals. The absorption of these foods in the human body is facilitated by digestion.
The availability of food depends on a number of factors, including the economy and climate. In developed countries, many people have enough money to buy a variety of nutritious foods. However, they often eat poorly, consuming too much fat, salt and sugar and not enough fruits, vegetables and fiber. This type of diet increases the risk of obesity and some health conditions.
A healthy diet provides the energy and nutrients needed to keep a person active throughout the day. It also supports a healthy weight, lowers the risk of chronic health conditions, such as heart disease and diabetes, and promotes growth in children.
Diets vary considerably around the world and even within a country. Historically, these differences were partly due to geographic factors. People living near oceans might eat more fish, for example. In cold regions with short growing seasons, people might consume more root crops like potatoes. People in warm, wet lowlands might prefer grains like rice.
Local customs and traditions also influence what food is eaten. For example, English tradition favors roast beef and Yorkshire pudding at special occasions. Many Asian cultures serve rice with almost every meal.
Improved methods of processing, preservation, storage and shipping allow people to enjoy foods that are produced far from their homes. Olive oil from Spain, cheese from France and sardines from Norway are examples of foods that can be easily transported long distances.
The science of food is a broad field that includes the study of nutrition, the physico-chemical properties of foods and their flavors, and the ways in which these foods are preserved and processed. It also includes the development of new food products and their safety evaluation. The science of food also addresses issues such as how to make foods more appealing.
An important part of the food supply is the production of grain. The most common grain is wheat, but people also grow rice, maize and barley for food. Many countries are also involved in the cultivation of tropical plants for food, such as bananas, plantains and pineapples.
People preserve foods by cooking, freezing, drying, smoking or pickling. They may also use chemicals, such as preservatives, to add flavor and extend the life of foods.
The food industry is a large and complex part of the global economy. Its products range from raw materials for the manufacturing of other food products to ready-to-eat meals. The industry is regulated in many countries to ensure that the public health is protected and that food is safe for consumption.