Food is any substance consumed for nutritional support, usually consisting of carbohydrates, fats, protein, and vitamins and minerals. It provides energy and sustains life, allowing organisms to grow and reproduce. The food supply of humans, animals, and plants may be influenced by climate, geography, culture, and technology. People generally eat a wide variety of foods.
Early humans were hunter-gatherers and ate only those foods available in their immediate environment. Over time, people developed agriculture and animal husbandry and grew to depend on a regular supply of fruits, vegetables, grains, legumes, meat, dairy, and eggs for their survival. Today, many foods are available all over the world because of improved methods of farming and transportation. People are also able to choose from a much larger variety of foods, depending on the season and their geographic location.
The nutritional value of food varies widely. The body needs a balanced diet to be healthy, and the choices made about what, when, how much, and how often to eat are important lifestyle decisions. Eating a balanced diet helps reduce the risk of certain diseases, such as heart disease, high blood pressure, type 2 diabetes, and some types of cancer.
Most of the calories in food come from carbohydrates, mainly sugars and starches. Carbohydrates provide energy for the body and brain. Vegetables and fruit are good sources of carbohydrates. Some vegetables and fruits are high in dietary fiber, which helps prevent constipation and promotes normal bowel movements.
Dietary fiber also helps keep cholesterol levels in check. Animal products, including meats and cheeses, are high in protein. Protein helps the body build and repair tissues, and maintain muscle. Animal products also provide essential fatty acids, which help the body control inflammation and the immune system.
Fats provide more energy than carbohydrates or protein, and they help to insulate and protect the body and organs. Common fats include vegetable oils, butter, lard, and the fat in milk, eggs, and some cheeses.
People may need to modify their eating habits to accommodate health concerns. For example, some people with celiac disease must avoid gluten, a protein found in wheat and related cereal grains. Others must follow a low-sodium diet to manage high blood pressure or to prevent kidney stones. People who want to lose weight must limit high-fat foods, which can cause bloating and water retention. Eating too little can lead to malnutrition. In addition, some people develop eating disorders that can be harmful to their health.