Food is any material consumed by an animal to give nutrition to an organism for the production of nourishing material. In humans, food is generally of plant, vegetable or fungi origin, and has various important nutrients, including protein, carbohydrates, vitamins, minerals or fats. The human body needs a varied amount of food to sustain life; a deficit results in death. A balance is required to maintain health and a well-balanced diet is an ideal for a healthy lifestyle.
Some food products are naturally complete proteins; the proteins are present in the form of albumen, casein or whey, with the highest amounts being found in milk and eggs, although other food types can have these constituents as well. For instance, some plant foods like vegetables, nuts and seeds contain all the necessary amino acids that are needed to produce enzymes, the building blocks of proteins. Nuts, eggs and soybeans are a good source of protein.
There are two main groups of macronutrients – carbohydrates and proteins. Most food is made up of carbohydrates; they are the main source of energy in the body and play a major role in cell metabolism. They can be divided into several main groups such as monosaccharides, complex carbohydrates and simple carbohydrates. Simple carbohydrates are those that can be broken down easily by the body, whereas complex carbohydrates require more energy to be metabolised and this is the source of a high amount of dietary fibre. Macronutrients are important to a healthy diet, and research has shown that people who have a higher intake of fibre tend to live longer, healthier lives.