Almost all foods are of plant or animal
origin, although there are some exceptions. Foods not coming from animal
or plant sources include various edible fungi, including mushrooms. Fungi
and ambient bacteria are used in the preparation of fermented and pickled
foods such as leavened bread, wine, beer, cheese, pickles, and
Many cultures eat seaweed, which is a
protist, or blue-green algae (cyanobacteria) such as Spirulina.
Additionally, salt is often eaten as a flavoring or preservative, and
baking soda is used in food preparation. Both of these are inorganic
substances, as is water, an important part of human diet.
Many plants or plant parts are eaten as
food. There are around 2,000 plant species which are cultivated for food,
and many have several distinct cultivars. Plant-based foods can be
classified as with the nutrients necessary for the plant's initial growth.
Because of this, seeds are often packed with energy, and are good sources
of food for animals, including humans. In fact, the majority of all foods
consumed by human beings are seeds.
These include cereals (such as maize,
wheat, and rice), legumes (such as beans, peas, and lentils), and nuts.
Oilseeds are often pressed to produce rich oils, including sunflower, rape
(including canola oil), and sesame.
Fruits are the ripened extensions of
plants, including the seeds within. Fruits are made attractive to animals
so that animals will eat the fruits and excrete the seeds over long
distances. Fruits, therefore, make up a significant part of the diets of
most cultures. Some fruits, such as pumpkin and eggplant, are eaten as
Vegetables are a second type of plant
matter eaten as food. These include root vegetables (such as potatoes and
carrots), leaf vegetables (such as spinach and lettuce), stem vegetables
(such as bamboo shoots and asparagus), and inflorescence vegetables (such
as globe artichokes and broccoli). Many herbs and spices are
Animals can be used as food either
directly, or indirectly by the products they produce. Meat is an example
of a direct product taken from an animal, which comes from either muscle
systems or from organs. Food products produced by animals include milk
produced by bovines, which in many cultures is drunk or processed into
dairy products such as cheese or butter. In addition birds and other
animals lay eggs, which are often eaten, and bees produce honey, a popular
sweetener in many cultures.
Some cultures consume blood, some in the
form of blood sausage, as a thickener for sauces, a cured salted form for
times of food scarcity, and others use blood in stews such as civet.